united states army aviation center fort rucker, alabama

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United States Army Aviation Center Fort Rucker, Alabama DECEMBER 2002

STUDENT HANDOUT

TITLE: AH-64D AIRCRAFT SURVIVABILITY EQUIPMENT (ASE)

FILE NUMBER: 11-0926-8.5 PROPONENT FOR THIS STUDENT HANDOUT IS: 110th AVIATION BRIGADE ATTN: ATZQ-ATB-AD Fort Rucker, Alabama 36362-5000 FOREIGN DISCLOSURE RESTRICTIONS: This product has been reviewed by the product developers in coordination with the USAAVNC foreign disclosure authority. This product is releasable to military students from foreign countries on a case-by-case basis.

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Terminal Learning Objective: At the completion of this lesson you (the student) will:

Action: Operate the AH-64D Aircraft Survivability Equipment (ASE) components.

Condition: Given an AH-64D helicopter or training device, TM 1-1520-251-10, and TC 1-251.

Standard: In accordance with TM 1-1520-251-10 and TC 1-251.

Introduction:

The Aircraft Survivability Equipment (ASE) subsystem provides automatic detection, identification, classification, and warning of various types of radar and laser emitters. It also provides radar and infrared (IR) emitter countermeasures. The subsystem consists of several Government Furnished Equipment (GFE) components, a MIL-STD-1553B Multiplex (MUX) interface, associated wiring, and installation hardware.

The ASE suite is heavily relied upon for the survival of aircraft and crewmembers in a combat environment. A good working knowledge of the ASE systems is essential to operating the ASE suite.

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A. Enabling Learning Objective 1

After this lesson you will:

Action: Identify the characteristics of the AH-64D Aircraft Survivability Equipment (ASE) suite.

Conditions: Given a written test without the use of student notes or references.


1. Learning Step/Activity 1

Figure 1. Aircraft Survivability Equipment (ASE) System List

a. ASE Systems

(1) Passive threat warning systems

(a) AN/APR-39A(V)4 Radar Signal Detecting Set (RSDS)

(b) AN/AVR-2A Laser Detecting Set (LDS)

(c) AN/APR-48A Radar Frequency Interferometer (RFI)

(2) Active Electronic Countermeasures (ECM) systems

(a) AN/ALQ-136(V)5 Radar Jammer (RJAM) Countermeasures Set

(b) AN/ALQ-144A(V)3 Infrared Jammer (IRJAM) Countermeasures Set

(c) M141 General Purpose Aircraft Dispenser (CHAFF)

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Figure 2. ASE Component Locations

b. ASE Component Locations

(1) The Data Management System (DMS) replaces the dedicated console mounted control panels used in earlier aircraft models.

(a) The SPs control the operation of the ASE suite via the MUX bus or direct Input/Output (I/O) interfaces, based on actions taken on the Multipurpose Displays (MPDs) and/or cyclic grip in each crewstation.

(b) The Display Processors (DPs) process MPD selections and provide display of ASE related information on the MPDs.

(c) The Weapons Processors (WPs) perform the control and monitoring functions for the RFI system either directly via MUX bus channel 3 or via the Fire Control Radar (FCR) Programmable Signal Processor (PSP) and MUX bus channel 4, depending on the aircraft configuration.

(2) The Communication Interface Unit (CIU) is located in the forward portion of the right Extended Forward Avionics Bay (EFAB).

(a) The CIU generates aircraft voice warning messages and caution/advisory tones.

(b) It also distributes audio within the aircraft including Radar/Laser Warning Receiver (RLWR) threat warning audio from the AN/APR-39A (V)4.

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(3) The AN/APR-39A (V)4 digital processor and the AN/AVR-2A(V)1 interface unit comparator are located in the left aft avionics bay.

(a) The APR-39(V) forward radar receiver is mounted in the nose of the aircraft.

(b) The aft receiver is located in the top portion of the vertical stabilizer.

(4) The AN/APR-48A RFI system consists of the following:

(a) RFI antenna array

(b) RFI receiver

(c) RFI processor components

1) The RFI antenna array and the RFI receiver are mounted just below the Mast Mounted Assembly (MMA) on the MMA pedestal that is located above the rotor mast.

2) The RFI processor is located in the aft portion of the left EFAB.

(5) The AN/ALQ-136(V)5 Receiver/Transmitter (R/T) is mounted in the forward portion of the left EFAB.

(6) The AN/ALQ-144A(V)3 IRJAM transmitter is mounted on the top of the aircraft, slightly aft of the rotor mast.

(7) The M141 CHAFF components are mounted on the left aft side of the tailboom.

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Figure 3. ASE Antenna/Sensor Locations

c. ASE Antenna/Sensor Locations

(1) The APR-39A employs four antenna/detectors

(a) One APR-39A antenna/detector is located on each side of the aircraft, directly aft of the aircraft nose.

(b) Two antennae are mounted on a standoff fairing located at the top of the vertical stabilizer, facing aft.

(c) The RSDS blade antenna is mounted on the underside of the tailboom between the Ultra High Frequency (UHF) blade antenna and the aft jack pad.

(2) The AH-64D employs a total of four AVR-2A LDS sensor units.

(a) Two are mounted on either side of the tailboom, just aft of the aft deck.

(b) Two are mounted on standoffs on either side of the main rotor assembly, at the top of the fuselage.

(3) Two antennas are utilized by the RFI

(a) The RFI antenna array is mounted below the MMA on the pedestal and is oriented to be coincident with the FCR centerline.

(b) The RFI receiver, which contains the aft coarse Direction Finding (DF) antenna, is also mounted below the MMA on the pedestal and is oriented 180° out from the antenna array.

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(4) The AN/ALQ-136(V)5 radar jammer employs two antennas

(a) The receive antenna is mounted on the forward edge of the doghouse fairing, just above and behind the pilot’s head.

(b) The transmit antenna is mounted on the Aircraft Interface Assembly (AIA) to the left of center, facing forward.

Figure 4. ASE Subsystem Interface Diagram

d. ASE Subsystem Interface

(1) Management of the ASE subsystem is performed by the SPs and WPs. The MIL-STD-1553B MUX bus provides interface between the SPs and WPs and the following:

(a) DPs

(b) Electrical Power Management System (EPMS)

(c) FCR system

(d) RLWR system

(e) RFI system

(2) The remaining ASE interface is provided as direct I/O via various discrete and analog signals to/from the SPs.

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(3) The SP and WP control subsystem operation and monitor subsystem information via the MUX bus and direct I/O interfaces. They transfer aircraft and ASE system status, RLWR and RFI threat information, radar and infrared jammer information, and Chaff count to the DPs.

(4) The DPs combine ASE subsystem information with system control inputs to generate ASE displays on the MPDs. The DPs read and interpret crew selections and send control commands to the SP.

(5) The SPs receive and validate crew inputs from the MPDs, determine the appropriate control to be performed, and transmit control commands to the required component.

(6) The SPs provide ASE related cautions and advisories for display on the Up-Front Displays (UFDs)/ Enhanced Up-Front Display (EUFD).

(7) The SPs transfer Chaff count to/from the Load Maintenance Panel (LMP).

(8) The EPMS interfaces with the SPs via the MUX bus and the ASE suite via direct lines.

(a) The SPs control the Electrical Load Centers (ELCs) over the MUX bus.

(b) The ELCs provide switched power and power control via direct lines to each system.

(9) With an operational FCR system installed in the aircraft, the RFI system is connected to MUX bus channel 4 and is controlled via the FCR Programmable Signal Processor (PSP).

(a) The FCR PSP is controlled by the WPs over MUX bus channel 3.

(b) If the FCR is not installed or is not operational, the RFI can be connected directly to MUX bus channel 3 for the required interface with the WPs.

1) Connections for MUX bus channel 3 and 4 are provided in the aft portion of the left EFAB for the RFI processor.

2) The transfer of RFI MUX bus channels is accomplished by physically swapping the RFI processor MUX bus connectors from one set of bus channel connections to the other.

(10) The CIU provides dissemination of RLWR threat voice warning messages to both crewstations.

(11) The IFF system generates a blanking pulse, sent via the LDS, to the RSDS. This prevents interference between the two systems operating in approximately the same frequency range.

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Check On Learning

1. Where is the AN/APR-39A(V)4 Radar Signal Detecting Set (RSDS) digital processor located in the aircraft?

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2. Where are the AN/ALQ-136(V)5 Radar Jammer Countermeasures Set (RJAM) transmit and receiver antennas mounted?

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3. What replaces the electronics module for the M141 General Purpose Aircraft Dispenser (CHAFF) system in the AH-64D aircraft?

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4. Which system provides a blanking signal to the ANAPR-39A(V)4 RSDS while it is transmitting, to prevent interference between the two systems that operate in the same approximate frequency range?

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B. Enabling Learning Objective 2


Action: Identify the characteristics of the AN/APR-39A(V)4 Radar Signal Detecting Set (RSDS).




a. Early Military Warning and Detection Systems

(1) Until the 20th century, military warning and detection methods lagged far behind the tactics of surprise.

(a) Scouts and sentries were the backbone of early warning systems.

(b) Sometimes animals were used to detect the approach of an enemy.

(2) The balloon was the first application of technology to the problem.

(a) Despite some isolated examples of success in the American Civil War, the Spanish-American War, and World War I, the balloon's role in warning and detection was short-lived and of little significance.

(b) A major factor of the withdrawal of the observation balloon from military service was the initiation of airplane reconnaissance missions.

(3) The airplane itself rapidly developed into such a powerful offensive weapon that it presently constitutes a most serious threat (second only to ballistic missiles) to the national security of all nations.

(a) Most countries have some type of system to warn of an impending attack. Radar is the most common sensor used in warning systems.

(b) Radar can detect incoming aircraft and guide missiles to those aircraft, so a system to let the aircraft know they were "illuminated" was needed.

b. Radar Warning Systems

(1) Radar that provides information on the type, range, and bearing of aircraft, have characteristics that make it vulnerable to detection.

(2) All radar falls within certain frequency ranges.

(3) The pulse width, repetition frequency, and interval of radar systems used to track and lock onto aircraft are known.

(4) The characteristics of these systems (tracking and missile guidance) are known, the radar warning system AN/APR-39(V)4 was designed and built to receive and display those systems which could detect and attack our aircraft.

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Figure 5. AN/APR-39A(V)4 RSDS Components

c. AN/APR-39A(V)4 RSDS

The RSDS is a passive electronic warfare system that provides visual and aural indications of the presence of, and the bearing to, active radar transmitters.

d. Characteristics of the RSDS

(1) Omni-directional and provides detection, identification, classification, and prioritization of pulse and pulse Doppler radar emitters.

(2) Supplies the mode and bearing information about these emitters.

(3) Detects pulse radar signals usually associated with hostile FCR. They typically operate in the low band (C/D 0.5 - 2 GHz) and high bands (E-M 2 - 100 GHz).

(4) Pulse radar signals are seen as potential threats to the aircraft and are displayed as symbols on the MPDs.

(5) Generates computer-synthesized voice threat messages for audible indications of potential threats.

(6) The visual and audible indications occur simultaneously to indicate the type of threat, threat mode, and the relative bearing to the aircraft.

(7) Consists of the following components:

(a) A digital processor

(b) Two radar receivers (one forward and one aft)

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(c) Four hi-band spiral antenna-detectors (two forward and two aft)

(d) A lo-band blade antenna

Figure 6. CP-1597A/APR-39A(V) Digital Processor

e. RSDS Components

(1) Digital Processor CP-1597A/APR-39A(V)

(a) The digital processor is the heart of the RSDS.

(b) It receives 28 Vdc power from ELC1 and provides the required operating voltages for the system.

(c) It performs the threat processing and reporting functions, and executes Built-In-Test (BIT) routines for the system.

(d) The digital processor is located in the left aft avionics bay. It is situated just aft of the LDS Interface Unit Comparator (IUC).

(2) User Data Module (UDM)

(a) The RSDS employs a removable UDM, which is mounted in the top of the digital processor.

(b) The UDM contains the classified portion of the system Operational Flight Program (OFP) and the classified Emitter Identification Data (EID) files.

(c) The EID files contain the threat library, which includes threat signal parametric data.

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(d) The UDM can be removed at the unit level and replaced with updated cards to accommodate new and changing threats.

(e) The UDM allows the RSDS to be tailored to the specific theater of operations and/or current mission requirements.

(f) Removal of the UDM from the digital processor declassifies the RSDS system.

Figure 7. R-2218/APR-39 (V) Radar Receiver

(3) Forward/aft radar receivers (R-2218/APR-39(V))

(a) The radar receivers supply operating power to the antenna-detectors.

(b) They receive, filter, and amplify video inputs from the antenna-detectors and provide these signals to the digital processor for processing.

(c) The radar receivers also perform initiated Built-In-Test on command from the digital processor.

(d) The forward radar receiver is mounted in the nose of the aircraft, between the AIA and the CPG yaw pedals.

(e) The aft radar receiver is located in the top portion of thevertical fin.

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Figure 8. AS-3548A/AS-3549A Antenna-Detector and AS-2890/APR-39(V) Blade Antenna

(4) Spiral antenna-detectors AS-3548A/AS-3549A

(a) There are four hi-band spiral antenna-detectors located around the aircraft.

1) The antenna-detector characteristics determine the frequency range of the system.

2) The positioning of the antenna-detectors provides for 360° coverage about the aircraft with substantial overlap.

(b) Each unit contains two spiral antenna elements.

1) One antenna operates in the E-J bands

2) One operates in the Millimeter Wave (MMW) region.

3) This provides for hi-band coverage in the E-M frequency range.

(c) Each of the spiral antenna elements receives RF signals in their respective band and supplies them to the detector circuits.

1) The detector portion of the antenna-detector employs an elaborate set of filter banks that extract the video from the received RF in each band.

2) The resultant video outputs are summed and provided as a composite video signal to the appropriate radar receiver on a single coaxial line.

(d) There are two antenna-detector types used to cover the four quadrants around the aircraft.

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1) The AS-3548A antenna-detectors contain clockwise spiral antenna elements and are optimized for right-hand circular polarized signals.

2) The AS-3549A antenna-detectors contain counterclockwise spiral antenna elements and are optimized for left-hand circular polarized signals.

(e) The antenna-detectors must be mounted in the correct quadrant of the aircraft or bearing errors will occur and “blind spots” in the reception pattern may occur. Do not confuse right and left polarization with right and left sides of the aircraft.

(5) Blade antenna (AS-2890/APR-39(V))

(a) The blade antenna provides reception of lo-band (C/D) RF energy.

(b) The blade antenna is mounted on the underside of the tailboom between the UHF blade antenna and the aft jack pad.

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Figure 9. AN/APR-39A(V)4 RSDS Components

f. System Operation

(1) The digital processor supplies Direct Current (DC) operating power to the two radar (video) receivers and superimposes a self-test signal on the power line during self-test. It receives four video inputs from the two radar receivers and RF signals from the lo-band (C/D) blade antenna.

(a) These signals are sorted and processed to determine received signal parameters, which include: Pulse Repetition Interval (PRI), Pulse Frequency Modulation (PFM) characteristics, pulse amplitude (signal strength), and scan type.

(b) The RSDS processes video from the selected band and determines Pulse Width (PW) and Angle-Of-Arrival (AOA) of the incoming signal.

(c) AOA is determined by comparing antenna-detector pulse amplitude levels with the pulse amplitude levels of adjacent antenna-detectors.

(d) This analysis occurs in conjunction with the hi-band signal analysis to determine the threat type and current threat mode (search, acquisition, track, lock-on/launch, etc.)

(e) These signal parameters are stored in a track file where the digital processor compares them to the threat library stored in the EID files located in the UDM. The radar warning receiver track file contains threat information for up to 10 RLWR detected emitters.

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(f) The track file includes the following data:

1) Threat count

2) Threat priority

3) Threat type

4) New threat signal - bold for 3 seconds

5) Threat signal no longer detected - ghosted for 10 seconds

6) Threat mode: search, acquisition, track, or lock-on/launch

7) Uncorrelated C/D band threat

8) Threat azimuth

(g) When the intercepted signal matches the parameters of a threat stored in the EID, the appropriate symbol and synthetic voice commands are generated.

(h) The digital processor performs threat processing based on these inputs and generates threat symbology data that is provided to the DPs for the display of threats on the ASE and Tactical Situation Display (TSD) pages.

(i) If the received signal parameters do not match a threat in the EID files, the digital processor generates the threat data for an unknown threat. An unknown threat is indicated by the symbol “U.”

(j) The system does not provide center frequency resolution for detected signals.

(k) The digital processor generates computer-synthesized voice threat messages that are routed through the CIU to the pilot and Copilot/Gunner (CPG) headsets. The communication control panels in each crewstation provide selection and volume control of this audio.

(l) The digital processor monitors incoming signal activity and when this activity exceeds the system processing capability, it generates a synthetic voice message (Threat Detection Degraded) alerting the crew that the system in a degraded mode.

(m) The digital processor provides interface with other aircraft components and systems.

(2) The system receives a lo-band blanking signal from the Identification Friend or Foe (IFF) transponder while it is transmitting.

(a) The digital processor inhibits the processing of received C/D band signals during this blanking interval.

(b) This is accomplished to prevent IFF system interference in the lo-band frequency range.

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Figure 10. ASE Page

g. ASE Page

(1) The ASE page is accessible via the main menu, TSD, TSD UTIL, WPN, or the WPN UTIL pages on the MPD. The ASE page provides numerous ASE control options, status windows, and displays the ASE footprint for threat/emitter symbol presentation.

(2) The ASE footprint is the area on the map defined by the circle.

(a) The footprint is primarily used to segregate RLWR threat detection from RFI threat detection.

(b) Symbols representing RLWR threats appear on the inside of the footprint.

(c) RFI detected threat/emitter symbols appear on the outside of the footprint.

(3) The Ownship symbol is displayed in the center of the ASE page.

(a) It is used to indicate the bearing of detected threats from the aircraft and to display the RJAM jamming indication (cyan flashing lightning bolt).

(b) The ownship symbol is cyan in color on an MPD in color mode.

(4) The system provides threat information on the ASE and TSD pages:

(a) Detected threat type is indicated through the use of alphanumeric and other types of symbols.

1) RLWR detected threats/emitters are portrayed in yellow on an MPD in color mode.

2) RFI detected threats/emitters are portrayed in one of two colors based upon their friendly/hostile status.

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a) Friendly emitters are displayed in cyan.

b) Hostile and unknown (gray) emitters are displayed in yellow.

(b) Newly detected RLWR threats are indicated by a boldface symbol for three seconds.

(c) When an RLWR threat signal drops out of the environment and is lost, the corresponding symbol goes partial intensity yellow (ghosted) for ten seconds and then disappears.

(d) The detected threat mode is indicated by a modified symbol to depict the threat modes of search, acquisition, track, and lock-on/launch for radar threats.

(e) The direction to the threat is displayed in relation to the ownship.

(5) RLWR threat symbols are always displayed at the inside perimeter of the footprint.

(a) The one exception is the uncorrelated C/D band threat symbol, which always appears directly in front of the ownship symbol on the display.

(b) The distance from the center to the edge of the footprint does not in any way represent threat range or lethality (severity) information.

(c) A maximum of seven top prioritized RLWR threat symbols can be displayed. The threat displays are accompanied by the appropriate voice threat messages, annunciated via the Intercommunication System (ICS).

1) The pulse radar threats can be displayed in any one of four possible threat modes.

2) It is important to note that not all pulse radar threats have all four threat modes associated with them.

3) The threat mode symbology is presented in yellow and is delineated as follows:

a) Search - symbol only

b) Acquisition - symbol with a box

c) Track - symbol with a box and a dashed line to the ownship

d) Lock-On/Launch - symbol with a box and a dashed line to the ownship with the box flashing at a 4 Hz rate

(6) Threat symbol display priority is based on lethality assessment and time of occurrence of the incoming threat data into the DPs (i.e., the first threat symbol data has highest priority, last threat symbol data has lowest priority).

(7) When any of the first three threat symbol azimuths are within 15° of each other, de-clumping rules will be applied.

(a) The number one threat symbol will be displayed at its original azimuth.

(b) Threat symbol numbers two and three may be displaced in order to maintain at least 15° separation from threat symbol number one and from each other.

(c) All other threat symbols will be displayed at their original azimuths.

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(8) ASE page functions

(a) A/C Heading status window

Displays the current aircraft magnetic heading unless both Embedded Global Inertials (EGIs) have failed, at which time the map rotation freezes at the last known heading and the digital readout is removed from the window.

1) The aircraft heading map freeze cue is displayed as a single horizontal line through the digital readout within the aircraft heading status window.

2) This single horizontal line indicates that the map is in a static state and the detected threats are frozen on the display.

3) The digital readout is continually updated during a map freeze condition to provide a dynamic display of current magnetic heading, regardless of the map orientation.

(b) ASE UTIL page button

Used to access the ASE UTIL page, which allows the crew to configure the ASE subsystem for specific threats or missions and conduct other utility functions.

(c) ASE autopage grouped options

Allows the crew to configure the ASE autopage function independently in each crewstation. This selection is also available on the TSD UTIL page.

1) The ASE autopage function is designed to immediately display a TSD page with ASE footprint when an RLWR or RFI threat is detected that meets or exceeds the selected threat state threshold.

2) Options available for threat state threshold are:

a) Search (SRH)

b) Acquisition (ACQ)

c) Track (TRK)

d) Off

3) When an ASE autopage triggering event occurs, the ASE information can be automatically presented to the crew by (in order of precedence):

a) Updating a currently displayed ASE page.

b) Providing ASE information on a currently displayed TSD page by changing the TSD SHOW page button settings (if necessary) to reflect presentation of ASE information.

c) Autopaging to the TSD page and changing the TSD SHOW page button settings (if necessary) to reflect presentation of ASE information.

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4) If the ASE or TSD pages are not presented when the ASE autopage function is triggered, the TSD page with ASE information will be autopaged on the right MPD unless the right MPD already displays a FLT page or that crewstation’s only emergency ENG page. In these cases, either:

a) The left MPD is not currently displaying a FLT page or emergency ENG page and, therefore, the TSD page with ASE information will be presented on the left MPD.

b) The left MPD is currently displaying a FLT page or emergency ENG page and, therefore, the TSD page will not be presented on any MPD in that crewstation and the ASE autopage function will not transpire.

5) The ASE autopage function can be completely suppressed in a crewstation by selecting the off option.

(d) RLWR On/Off button

Used to power the integrated RLWR on and off. This includes both the AN/APR-39A(V)4 RSDS and the AN/AVR-2A LDS.

1) The RLWR defaults to off during initialization.

2) When turned on, the audio voice message “APR-39 Power-Up” is generated by the RSDS digital processor.

3) If the AVR-2A IUC is not installed and the AN/APR-39A(V)4 is employed in a stand-alone configuration, the button legend is changed to “RWR” to reflect that configuration.

4) This button legend is removed from the display if the RSDS digital processor is not installed.

(e) RLWR emitter status window

Displays the current number of RLWR threat symbols being displayed on the ASE and TSD pages. This status window is removed from the display if no RLWR threats are displayed.

(f) Next waypoint heading status window

Displays the current magnetic heading to the next waypoint unless both EGIs have failed, at which time the map rotation freezes at the last known heading and the digital readout is removed from the window.

1) The next waypoint heading map freeze cue is displayed as a single horizontal line through the digital readout within the next waypoint heading status window.

2) This indicates that the map is in a static state and the detected threats are frozen on the display.

3) The digital readout is continually updated during this map freeze condition to provide a dynamic display of next waypoint magnetic heading, regardless of the map orientation.

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Figure 11. ASE UTIL Page

h. ASE UTIL Page

(1) The ASE UTIL page is accessible from the top level ASE page via the ASE UTIL page button. The ASE UTIL page contains functions used to configure the ASE subsystem.

(2) ASE Utility page functions

RLWR voice mode option - A two-state option button that allows the crew to select between normal and terse modes.

(a) During system initialization, the voice mode defaults to the normal mode. This provides the crew with a full audio message format that includes specific threat type, threat bearing, and threat status.

(b) The terse mode supplies the crew with an abbreviated audio message format that includes generic threat type, bearing, and status. This mode reduces audio distractions when operating in a dense audio environment and/or dense threat signal environment.

(c) The RLWR voice mode button legend is changed to “RWR” if the RSDS is operating in a stand-alone configuration.

(d) The button legend is also removed from the display if the RSDS digital processor is not installed in the aircraft.

(e) Voice mode may be selected with RLWR off.

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Figure 12. TSD Page

i. TSD Page

(1) The TSD page displays both RLWR and RFI threat/emitter symbols in much the same manner as on the ASE page.

(2) These symbols are displayed on both the navigation and attack phases of the TSD provided that the RFI threats and RLWR threats options are selected for display on the appropriate TSD SHOW page.

(3) These display options can be manually selected in each crewstation or can be automatically selected by the system as part of the ASE autopage function for each crewstation.

(4) On the TSD page, the ASE footprint is only displayed if RLWR and/or RFI threats are selected from the SHOW page and at least one threat exists for display.

(5) The TSD ASE footprint is a box, displayed just inside the TSD map boundary box.

(a) RLWR

1) Symbols representing RLWR threats are displayed on the inside of the footprint.

2) RLWR threat symbols appear at the inside perimeter of the TSD ASE footprint with the exception of an uncorrelated C/D band threat symbol.

3) This symbol always appears directly in front of the ownship symbol.

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(b) RFI

1) RFI detected threat/emitter symbols are displayed on the outside of the footprint.

2) RFI threat/emitter symbols appear at the outside perimeter, between the footprint and the TSD map boundary box.

Figure 13. TSD UTIL Page

j. TSD UTIL Page

(1) The TSD UTIL page provides access to the ASE page via the ASE bezel button.

(2) In addition, the ASE autopage function is available for configuration in each crewstation via the ASE autopage options.

(3) This multi-state option button provides the same selections and capability as the ASE autopage grouped options on the ASE page.

Both places reflect the last commanded state in each crewstation.

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Figure 14. DMS VERS Page

k. DMS VERS Page

(1) The DMS VERS page provides a means to verify the current software versions loaded in the associated aircraft components/systems.

(2) Upon initial power-up of the RLWR, the RSDS digital processor sends the currently loaded software OFP version and EID version statuses to the SPs via MUX bus channel 2.

(3) The SP sends the OFP and EID version statuses to the DPs that, in turn, display the RWR OFP and RWR EID versions on the DMS VERS page.

(4) The OFP and EID versions that should be installed in the current production RSDS configuration are 23.9 and 030 respectively.

(5) The 030 EID version is configured for the Persian Gulf.

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Figure 15. Communications Control Panel (CCP)

l. CCP

(1) The CCP in each crewstation contains an RLWR volume control located under the AUX bracket placard.

(2) This volume adjustment knob provides for independent volume adjustment for RLWR audio messages.

(3) The operator may set the RLWR audio to a comfortable level, or completely attenuate the audio if so desired (i.e., in a dense audio environment and/or a dense threat signal environment).

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Figure 16. DMS DTU Page

m. DTC Programmable ASE Data

The RLWR voice mode (normal or terse) can be programmed into the system via the DTC as part of the miscellaneous data upload function, which is selectable via the DMS DTU page via the MISCELLANEOUS option.

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Figure 17. ASE Top Level Page

n. Subsystem Initialization

(1) Ground initialization

If system power-up occurs while the aircraft is in an “on ground” condition (squat switch indicates on ground and both throttles are in the Off/Stop position), the ASE subsystem selections are initialized to a default state or to the DTC values. The system default values for RLWR are:

(a) RLWR On/Off mode - off

(b) RLWR voice mode - normal

(c) RLWR self-test mode - off

(d) ASE autopage selection - search

(2) Air initialization

If the power-up occurs while the aircraft is in an “in air” condition, the ASE subsystem selections are initialized to the values stored at power-down.

o. Subsystem Shutdown

During the shutdown routine, the system saves the following RLWR related ASE subsystem parameters in non-volatile memory

(1) RLWR On/Off mode

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(2) RLWR voice mode

(3) RLWR self-test mode

(4) ASE autopage selections

p. ASE Degraded Modes of Operation

(1) A dense signal environment will cause signal saturation for the RLWR system. When this occurs, the system automatically transitions to a degraded detection mode that will reduce system sensitivity for the duration of the saturation condition.

(2) A catastrophic CIU failure will cause a loss of the RLWR voice messages.

Figure 18. DMS NAV/ASE and RLWR IBIT Pages

q. RSDS System Built-In-Test (BIT)

(1) The RSDS is equipped with Continuous BIT (CBIT) and Initiated BIT (IBIT) features.

(a) The SPs monitor CBIT and IBIT status and send the results to the DPs for display.

(b) BIT status is also indicated to the crewmembers via voice messages generated by the digital processor.

(2) The RSDS CBIT routine, for both the RSDS and the LDS, is executed once every five minutes.

(a) The digital processor reports the status of this CBIT to the SPs via MUX bus channel 2.

(b) Should the same fault be detected in two successive CBIT routines, the digital processor flags the CBIT fault message to the SPs.

(3) The SPs continually monitor the digital processor for a CBIT fault.

(a) This is a single BIT fault message from the digital processor which indicates the RSDS or LDS has detected a failure while executing a continuous self-test.

(b) This fault is displayed on the DMS and DMS FAULT page. To identify the details of the fault, an IBIT must be performed.

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(4) As part of the overall CBIT routine for the system, the SPs also perform MUX bus communications checks (channel test) on the RSDS digital processor.

(5) IBIT can be performed via the NAV/ASE IBIT page by selecting RLWR bezel button. The RLWR IBIT button legend is either modified or removed from the display based on the status of the RSDS and/or LDS:

(a) If the AVR-2A IUC is not installed and the AN/APR-39A(V)4 is employed in a stand-alone configuration, the button legend is changed to “RWR” to reflect that configuration.

(b) On the IBIT page, the IBIT page title window and the vertical button legend also change to reflect the configuration.

(c) This button legend is removed from the NAV/ASE IBIT page if the RSDS digital processor is not installed.

(d) It is displayed with a non-selectable barrier if the system is turned off.

(6) The RLWR IBIT also performs a self-test of the LDS, if installed.

(a) Once an IBIT is initiated, the RLWR IBIT page is presented with the IBIT listing area displayed in the center of the page.

(b) The top line of the IBIT listing area is the test status line, which provides a status indication as to the progress of the IBIT.

1) During the self-test, the message “TEST IN PROGRESS” is displayed in inverse video on the test status line.

2) Upon completion of the self-test, the message “TEST ENDED” is provided on the test status line.

3) If the system fails to execute a self-test or the self-test fails to run to completion, the message “TEST FAILED TO RUN” is displayed in white text on the test status line.

4) If the ABORT button is selected during the self-test, the SPs ignore any faults detected for that IBIT sequence and the IBIT listing area displays only “TEST ABORT” in white text on the test status line.

(7) At the completion of the self-test, any faults detected and reported to the SPs by the RSDS digital processor are displayed in the IBIT listing area under the test status line

(a) In addition, any RSDS MUX faults detected by the SPs during the IBIT are also displayed.

(b) Up to two pages of IBIT faults can be displayed if necessary.

(c) If no failures are detected during the self-test, the message “NO FAULTS FOUND” is displayed on the first line of the IBIT listing area, under the test status line.

(8) During the IBIT routine, the digital processor generates one of two voice messages, depending upon the selected RLWR audio mode.

(a) With normal audio mode selected, the voice message “Self-Test, Set Volume 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12” is generated.

(b) With terse audio mode selected, the voice message “Self-Test, Set Volume 5, 4, 3, 2, 1” is generated.

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(9) Upon completion of a successful RLWR IBIT, the digital processor generates the voice message “APR-39 Operational.”

(10) If the digital processor detects an RLWR BIT failure, regardless of whether it is during the CBIT or IBIT routine, it generates a voice message to inform the operator as to which system has failed.

(a) If the RSDS fails BIT, the voice message “APR-39 Failure” is generated, regardless of the status of the LDS.

(b) If only the LDS fails BIT, the voice message “APR-39 Failure - Laser” is generated.

(11) The BIT function of the RSDS is not an end-to-end test of the system.

(a) The antenna-detectors and their associated coaxial cables are not tested during system BIT.

(b) The antenna-detectors and cables can be disconnected from the radar receivers and the system will pass both the CBIT and IBIT routines.

(12) The only method of testing the complete system is by utilizing a radar threat signal simulator to radiate the antenna-detectors and blade antenna with simulated threat signals and verify the visual and audible indications present in the crewstations.

Figure 19. DMS/DMS Fault Pages

r. AN/APR-39A(V)4 RSDS BIT Status/Associated Faults

The DMS presents the following RSDS related faults on the DMS page, DMS FAULT page, and/or RLWR IBIT page if the associated failure has been detected during PBIT, CBIT, or IBIT:

(1) ELC 1 RDR WRN RCVR PWR CNTL FAIL

This fault indicates that ELC1 has lost control of load controller KD319-A1 (radar warning receiver power control).

(2) RADAR WARNING LH FWD CHANNEL FAULT (RWR LH FWD)

(a) This fault indicates the RSDS left forward video channel has failed.

(b) The SP only monitors for this fault upon completion of RLWR IBIT.

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(c) This fault is only displayed on the RLWR IBIT page.

(3) RADAR WARNING RH FWD CHANNEL FAULT (RWR RH FWD)

(a) This fault indicates the RSDS right forward video channel has failed.



(4) RADAR WARNING LH AFT CHANNEL FAULT (RWR LH AFT)

(a) This fault indicates the RSDS left aft video channel has failed.



(5) RADAR WARNING RH AFT CHANNEL FAULT (RWR RH AFT)

(a) This fault indicates the RSDS right aft video channel has failed.



(6) RADAR WARNING CD BAND CHANNEL FAULT (RWR CD BAND)

(a) This fault indicates the RSDS CD band channel has failed.



(7) RADAR WARNING DP/1553 SRU FAULT (RWR/DP COMM)

(a) This fault indicates the RSDS digital processor 1553 MUX bus circuit card assembly has failed.



(8) RADAR WARNING CBIT FAULT (RWR FAULT)

(a) This fault indicates the RSDS or LDS has detected a failure during the CBIT routine.

(b) The SP monitors for this fault continuously via the MUX bus but it is only displayed on the RLWR IBIT page upon completion of the RLWR IBIT routine.

(9) RWR CHANNEL 2 BUS A NO RESPONSE (RWR FAULT):

(a) This fault indicates the RSDS digital processor is not responding to MUX channel 2 commands on Bus A.

(b) The SP monitors for this fault as part of the MUX bus communication routine when the RSDS is powered on.

(10) RWR CHANNEL 2 BUS B NO RESPONSE (RWR FAULT)

(a) This fault indicates the RSDS digital processor is not responding to MUX channel 2 commands on Bus B.


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(11) RWR FAIL (RWR FAIL)

(a) This fault indicates the RSDS digital processor is not responding to MUX channel 2 commands on Bus A or Bus B, or it did not complete the IBIT sequence normally.

(b) The SP monitors for this fault as part of the MUX bus communication routine when the RSDS is powered on and during IBIT.

Check On Learning

1. Where are RLWR detected threats displayed on the ASE and TSD pages of the Multi-

Purpose Display (MPD)?

_________________________________________________________________

_________________________________________________________________

2. How many RLWR threat symbols can be displayed simultaneously on the MPD?

_________________________________________________________________

_________________________________________________________________

3. What is the purpose of the ASE autopage function and what options are available for selection?

_________________________________________________________________

_________________________________________________________________

4. Where is the User Data Module (UDM) located and what is its function?

_________________________________________________________________

_________________________________________________________________

5. What is the purpose of the blade antenna within the Radar Search and Detection System (RSDS)?

_________________________________________________________________

_________________________________________________________________

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C. Enabling Learning Objective 3


Action: Identify the characteristics of the AN/AVR-2A Laser Detecting Set (LDS).


Standard: In accordance with TM 1520-251-10 and TC1-251


Figure 20. AN/AVR-2A LDS Components

a. AN/AVR-2A LDS

(1) The LDS is a passive electronic warfare system which detects, locates, and identifies hostile laser-aided weapon threats fired from both airborne and ground-based platforms.

(2) The system detects pulsed optical radiation which is illuminating the aircraft, processes detected data into laser threat messages, and sends these messages to the RSDS. The digital processor in the RSDS processes these inputs to provide for both visual and aural threat indications for the system.

(3) The LDS can also be used with both the RSDS and the Air-to-Ground Engagement System (AGES) to provide an engagement simulation system, in the operational training mode.

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(4) The system is composed of:

(a) Sensor Units (4 ea.)

(b) IUC

Figure 21. SU-130A/AVR-2A(V) Sensor Unit Location

b. System Components

(1) Sensor Units SU-130A/AVR-2A(V)

(a) The sensor units perform the actual laser detection function for the system and contain the necessary electronics to process detected laser signals.

(b) The two forward sensor units are mounted on standoffs on either side of the main rotor assembly, at the top of the fuselage.

(c) The two aft sensor units are mounted on either side of the tailboom, just aft of the aft deck.

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Figure 22. AN/AVR-2A Laser Detection Coverage

(d) Laser detection coverage

1) The four sensor units are strategically located around the aircraft with two mounted forward, facing forward and two mounted aft, facing aft. Each sensor unit provides a 100° Field-Of-View (FOV) in azimuth and ± 45° in elevation.

2) This configuration provides for 360° detection in azimuth and ± 45° in elevation with 10° of overlap in azimuth coverage, 5° for each FOV.

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Figure 23. SU-130A/AVR-2A(V) Sensor Unit

(e) System operation

1) Each sensor unit contains a laser detector array, consisting of four separate laser detectors. The array is mounted on the detector head assembly.

a) The laser detectors are located under a special optical window and supply coverage of three different spectral regions; Electro-Optical (EO) bands I, II, and III.

b) Two detectors, band IIIA and band IIIB, are employed in the band III region to provide the required band III detection coverage.

2) The characteristics of this special optical window provide for optimal transmission of energy in the near infrared range.

a) The near infrared range is the frequency band in which most lasers operate.

b) The sensor unit baffle is essentially a sunshade for the lower band III (band IIIB) detector. In straight and level flight, it shades the band IIIB laser detector from direct sunlight.

c) Shading is required because the background noise level experienced in band III is directly attributable to sunlight.

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3) Each sensor unit contains optical and electrical built-in test electronics to perform a self-test upon command from the IUC.

a) When a self-test command is received, the sensor unit disables detection of all externally generated signals and performs a self-test.

b) When the self-test is completed, the appropriate pass or fail message is sent to the IUC for processing and normal operation is resumed.

Figure 24. CM-493A/AVR-2A(V) IUC

(2) IUC CM-493A/AVR-2A(V)

(a) The IUC provides power and control for the sensor units, and performs threat processing and aircraft interface functions for the system.

(b) The IUC is located in the left aft avionics bay, third unit aft.

(c) It is mounted just forward of the RSDS digital processor, with which it directly interfaces.

(d) The IUC is the primary central processor and DC power supply for the LDS. It supplies regulated dc to the sensor units and processes laser threat data inputs from the sensor units.

(e) The IUC provides the control and timing necessary for interface with the sensor units.

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1) It provides interface with the RSDS and executes both periodic and IBIT routines for the system.

2) It performs the initiated BIT routine upon command from the primary SP via the RSDS digital processor.

3) It reports the system status to the digital processor for subsequent transmission to the SPs.

(f) The LDS was designed to operate in conjunction with the RSDS and is an integral part of the RSDS.

1) The IUC provides the majority of the wiring interface between the RSDS and the associated aircraft systems.

2) If the IUC is removed from the aircraft, an alternate connector configuration must be employed to permit the RSDS to operate.

Figure 25. AN/AVR-2A UDM

(g) The LDS employs a removable UDM, which is mounted in the face of the IUC. It is located behind the UDM cover plate, which is attached via four captive fasteners. A retaining wire is employed to secure the cover plate to the IUC when the cover plate is not installed.

(h) The UDM contains the classified operational software required for tactical operation of the system. This software is downloaded into volatile memory within the sensor units during system power-up and initialization, and the sensor units then become classified.

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(i) Removal of system power and removal of the UDM from the IUC effectively declassifies the system.

c. Threat Detection and Processing

(1) The LDS has the capability to operate in two modes, training and tactical.

(a) Training mode

1) In the training mode, the system operates with AGES in the Multiple Integrated Laser Engagement System (MILES).

2) This provides the crewmembers with a realistic combat tactical training system that closely simulates the effects of weapon engagements.

3) During training operation, the LDS operates as a detecting system in a MILES environment.

4) The operating software within the LDS does not recognize 0.904 micron gallium arsenide (GaAs) MILES laser hits as actual laser threats.

(b) Tactical mode

1) During tactical operation, the LDS detects, identifies, and characterizes three different types of optical signals.

2) When a sensor unit detects optical, coherent radiation within its FOV, it provides band and pulse characteristics as laser threat data to the IUC.

3) The IUC processes threat data by comparing received signal characteristics with stored parameters.

4) It then determines the existence of a laser threat, threat type, and AOA (quadrant resolution only).

5) This threat data is sent as laser threat messages to the RSDS digital processor to provide visual threat indications on the ASE and TSD pages.

6) The aural voice threat messages will be annunciated via the ICS.

7) Both visual and aural threat indications provide threat type and relative position information to the crewmembers.

8) Laser signals, which illuminate the aircraft within the FOV of the sensor, pass through the optical window onto the band I, II, and IIIA and IIIB detectors.

9) The detected signals are processed for validity and coherency determination, within the sensor unit.

10) If a validated laser detection signal is received, the sensor generates a threat message to describe the type (band) and pulse characteristics of the threat detected.

11) If band I and band II threats are detected simultaneously, the sensor determines which threat arrived last by its time of arrival data.

12) The last recorded threat is highest priority and will be the one displayed. The other threat signal will be discarded.

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13) If a band III threat is received during the processing of a band I or II threat, the processing of the band I or II threat will be terminated. Band III is associated with “beam rider”.

14) The sensor will immediately generate a band III threat message.

15) The IUC regularly polls the sensors for new threat data.

16) When a sensor is polled and a new threat is detected, it sends a threat message to the IUC.

17) When the IUC receives a threat message from one or more sensors, a timer window is opened.

18) All threat messages arriving within this window will be processed as simultaneous threat reports.

19) This function eliminates multiple quadrant displays of a single threat by more than one sensor.

20) This could be caused by reflections off of distant objects or the overlapping sensor FOV.

21) During this window, the IUC stores the threat data and sends a retransmit command to the sensors that originally sent the threat messages.

22) The retransmit command initiates a second transmission of the threat message for verification.

23) When the timer window closes, any new threat data received will be processed for display.

24) The IUC places pulse waveforms corresponding to threats on the respective left, right, forward, and aft video lines to the digital processor.

25) The digital processor analyzes the laser threat signals, prioritizing them along with RSDS detected threats.

26) The digital processor then produces laser threat data which is stored in a threat file along with any RSDS detected threat data.

d. Threat Annunciation

(1) The digital processor sends threat data to the DPs, when commanded by the primary SP. The DPs, in turn, generate the appropriate laser threat symbology for display ASE and TSD pages.

(2) This radar warning receiver track file that is transferred from the digital processor to the DPs contain threat information for up to 10 RLWR detected emitters and includes:

(a) Threat count

(b) Threat priority

(c) Threat type

(d) New threat signal - bold for 3 seconds

(e) Threat signal no longer detected - ghosted for 10 seconds

(f) Threat mode: search, acquisition, track, or lock-on/launch

(g) Uncorrelated C/D band threat

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(h) Threat azimuth

(3) In addition, the digital processor generates a corresponding computer-synthesized voice threat message, which is sent to the CIU for dissemination to the pilot and CPG headsets.

(4) The communication control panels in each crewstation provide selection and volume control of audio.

Figure 26. DMS NAV/ASE and RLWR IBIT Pages

e. AN/AVR-2A LDS System BIT

(1) The LDS is equipped with CBIT and IBIT features.

(2) The SPs monitor CBIT and IBIT status and send the results to the DPs for display.

(3) LDS BIT status is also indicated to the crewmembers via voice messages generated by the RSDS digital processor.

(4) The RSDS CBIT routine for the RSDS and the LDS is executed once every 5 minutes.

(5) The digital processor reports the status to the SPs.

(6) Should the same fault be detected in two successive CBIT routines, the digital processor flags the CBIT fault message to the SPs.

(7) The SPs continually monitor the digital processor for a CBIT fault.

(a) This is a fault message from the digital processor that indicates the RSDS or LDS has detected a failure.

(b) The fault is displayed on the DMS and DMS FAULT pages. An IBIT must be performed to identify the details of the failure.

(8) As part of the overall CBIT routine for the system, the SPs also perform MUX bus communications checks (channel test) on the RSDS digital processor.

(9) The IBIT can be initiated via the NAV/ASE IBIT page by selecting the RLWR bezel button. The RLWR IBIT button legend is either modified or removed from the display, based on the status of the RSDS and/or LDS.

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(a) If the AVR-2A IUC is not installed and the AN/APR-39A(V)4 is employed in a stand-alone configuration, the button legend is changed to “RWR” to reflect that configuration. On the IBIT page, the IBIT page title window and the vertical button legend also change to reflect the configuration.

(b) This button legend is removed from the NAV/ASE IBIT page if the RSDS digital processor is not installed

(c) A non-selectable barrier is displayed if the system is turned off.

(10) The RLWR IBIT also performs a self-test of the LDS, if installed.

(11) Once an IBIT is initiated, the RLWR IBIT page is presented with the IBIT listing area displayed in the center of the page.

(12) When a self-test is initiated, all threat processing is suspended.

(a) The LDS BIT test is not an end-to-end test of the system.

(b) The only method of testing the complete system is by utilizing a laser threat signal simulator to radiate the sensor units with simulated threat signals and verify the visual and audible indications present in the crewstations.

Figure 27. DMS/DMS Fault Pages

f. AN/AVR-2A LDS BIT Status/Associated Faults

The DMS presents LDS related faults on the DMS page, DMS FAULT page, and/or RLWR IBIT page if the associated failure has been detected during PBIT, CBIT, or IBIT:

(1) ELC 1 RDR WRN RCVR PWR CNTL FAIL (RWR PWR CNT)

This fault indicates ELC1 has lost control of load controller KD319-A1 (radar warning receiver power control).

(2) ELC 1 LASER WRN RCVR PWR CNTL FAIL (LWR PWR CNT)

This fault indicates ELC1 has lost control of the laser warning receiver power control.

(3) LASER WARNING LH FWD CHANNEL FAULT (LWR LH FWD)

(a) This fault indicates the LDS left forward sensor channel has failed.

(b) The SP only monitors for this fault upon completion of RLWR IBIT. This fault is only displayed on the RLWR IBIT page.

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(4) LASER WARNING RH FWD CHANNEL FAULT (LWR RH FWD)

(a) This fault indicates the LDS right forward sensor channel has failed.



(5) LASER WARNING LH AFT CHANNEL FAULT (LWR LH AFT)

(a) This fault indicates the LDS left aft sensor channel has failed.



(6) LASER WARNING RH AFT CHANNEL FAULT (LWR RH AFT)

(a) This fault indicates the LDS right aft sensor channel has failed.



(7) RADAR WARNING DP/1553 SRU FAULT (RWR/DP COMM)

(a) This fault indicates the RSDS digital processor 1553 MUX bus circuit card assembly has failed.



(8) RADAR WARNING CBIT FAULT (RWR FAULT)

This fault indicates the RSDS or LDS has detected a failure during the CBIT routine.

(9) RWR CHANNEL 2 BUS A NO RESPONSE (RWR FAULT)

(a) This fault indicates the RSDS digital processor is not responding to MUX channel 2 commands on Bus A.


(10) RWR CHANNEL 2 BUS B NO RESPONSE (RWR FAULT)

(a) This fault indicates the RSDS digital processor is not responding to MUX channel 2 commands on Bus B.


(11) RWR FAIL (RWR FAIL)

(a) This fault indicates the RSDS digital processor is not responding to MUX channel 2 commands on Bus A or Bus B, or it did not complete the IBIT sequence normally.

(b) The SP monitors for this fault as part of the MUX bus communication routine when the RSDS is powered on and during IBIT.

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Check On Learning

1. Which component contains the classified operational software required for tactical operation

of the Laser Detecting Set (LDS)?

_________________________________________________________________

_________________________________________________________________

2. Which component functions as the LDS power supply?

_________________________________________________________________

_________________________________________________________________

3. How many degrees of detection are provided by the LDS in elevation?

_________________________________________________________________

_________________________________________________________________

4. How many degrees of detection are provided by the LDS in azimuth?

_________________________________________________________________

_________________________________________________________________

5. How many sensor units are used by the LDS?

_________________________________________________________________

_________________________________________________________________

NOTES

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D. Enabling Learning Objective 4


Action: Identify the characteristics of the AH-64D Chaff Dispenser system.


Standard: In accordance with TM 1520-251-10 and TC 1-251.


Figure 28. CHAFF System Components

a. CHAFF System

(1) The AH-64D CHAFF system is an active Electronic Counter Measure (ECM) system designed to protect the aircraft from Anti-Aircraft Artillery (AAA), Surface-to-Air Missile (SAM), and Airborne Intercept (AI) radar threats.

(2) The system can dispense up to 30 chaff cartridges (M1) as a RF countermeasure against radar guided weapons systems.

(3) The chaff provides a cloud of reflective metal-coated fibers, which confuses returns to the threat radar. This assists in defeating the guidance capability of the threat radar system by affecting the systems ability to accurately track the aircraft.

(4) The chaff system is composed of four components

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(a) Support assembly and wire harness)

(b) Dispenser assembly

(c) Payload module

(d) Chaff safety switch

Figure 29. Chaff Support Assembly and Wire Harness

b. Major System Components

(1) Support assembly

(a) The support assembly is an adapter that accommodates the physical mounting of the chaff dispenser to the aircraft.

(b) The mounting ring has 10 mounting holes and is curved to accommodate the curvature of the tailboom.

(c) The support assembly is located on the left side of the tailboom, forward of the stabilator.

(d) Wire harness

1) The wire harness is approximately 14 inches long with an identical connector on each end.

2) A dummy stowage plug is mounted under the flat outer ring of the support assembly to provide a means of securing the aircraft receptacle dust cover when the wire harness is in use.

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Figure 30. CHAFF Assembly and Payload Module

(2) Dispenser assembly

(a) The dispenser assembly houses the payload module.

(b) It accepts dispense commands from the SPs and applies firing pulses to each chaff cartridge located in the payload module.

(c) The CHAFF is mounted to the support assembly.

(d) The dispenser assembly consists of a breech plate assembly, sequencer assembly, and a selector switch.

1) The breech plate assembly contains 30 contact pins and 15 spring grounding clips which mate with the impulse cartridges when a payload module is installed.

a) The contact pins are wired to the sequencer assembly electrical connector.

b) The breech plate also contains two guide pins and two fastener receptacles to align and secure the payload module to the dispenser assembly.

2) Sequencer assembly

a) Applies dispense signals to a dispenser breech plate contact pin to electrically fire the impulse cartridge.

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b) The sequencer assembly contains two rotary stepping switches, two circuit cards, and two electrical connectors.

c) The rotary stepping switch resets to its initial starting sequence when a payload module is installed, the safety pin is removed, and electrical power is applied to the dispenser assembly.

3) The Chaff/Flare selector switch is a two-position rotary switch labeled “C” (chaff) and “F” (Flare). The switch must be set to agree with the type of cartridges installed in the payload module.

a) The AH-64D configuration requires the switch be placed in the “C” position.

b) Flares are not currently utilized on the AH-64D aircraft.

c) The switch is mounted on the sequencer assembly and extends through an opening in the dispenser assembly front panel.

(3) Payload module

(a) The payload module holds 30 M1 chaff cartridges and their associated impulse cartridges.

(b) The payload module is mounted to the CHAFF.

(c) The payload module consists of a molded fiberglass block with compartments for 30 cartridges and a metal retaining plate.

(d) The retainer plate is to be installed after the cartridges are loaded.

1) The retainer plate fits onto the front of the block and is secured by two retaining screws.

2) The retainer plate contains slots to permit the impulse cartridges to mate with the breech plate contact pins and grounding clips.

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Figure 31. Chaff Safety Switch

(4) Chaff safety switch

(a) Electrically safes the CHAFF and arm/test connector when the safety pin is installed.

(b) The safety switch is located inside the tailboom on the left side of the aircraft, just forward of the CHAFF.

(c) The chaff safety switch is located on the tailboom, about three (3) inches forward of the CHAFF. It provides a means of safing the system to prevent inadvertent expenditure of impulse/chaff cartridges.

(d) The safety switch assembly consists of a two-piece aluminum housing and a double pole, double throw switch.

1) A hole in the center of the mounting flange allows the insertion of the ground safety pin from the outside of the aircraft.

2) When installed, the pin manually opens the switch contacts.

(e) When the safety pin is installed in the switch, chaff arm power is disconnected from the CHAFF and the chaff test connector. When the safety pin is removed from the switch, arm power is distributed to both the dispenser and the test connector.

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Figure 32. ASE Page

c. ASE Page

(1) The ASE page provides numerous chaff system control options and a chaff system status window.

(2) ASE page operation

(a) Chaff SAFE/ARM option

A two-state option button used to mode the chaff system between safe and arm. This button operates independently of the aircraft Safe/Arm pushbutton.

1) The chaff status defaults to safe at initial power-up, and reflects the last selected mode at all other times. The safe/arm status is a reflection of the selected state and not necessarily the actual safe/arm status of the system.

2) The system is in the safe state if the indicated status is safe.

a) If the safety pin is installed, the system can indicate ARM and be incapable of firing.

b) This selection is also available on the ASE UTIL page.

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(b) Chaff MODE option

Two-state options button used to select between the manual and program modes of the chaff system.

1) The manual mode provides the crew the ability to dispense one chaff cartridge each time the chaff dispense switch on the cyclic grip in either crewstation is actioned.

2) The program mode permits the crew to dispense chaff cartridges according to a predetermined program when the chaff dispense switch is actioned.

(c) Chaff status window

Displays the remaining chaff cartridges in the CHAFF payload module. This status is also displayed on the WPN page.

1) The CHAFF has no means of inventorying the number of chaff cartridges installed in the unit. The operator must enter the number of installed cartridges on the MPD ASE UTIL page, or the LMP.

2) The cartridge count is a decremental counter that counts down each time the SP issues a firing pulse. Consequently, the number of cartridges that should have been expended is deducted from the displayed count.

(d) ASE UTIL page button: Used to access the ASE UTIL page.

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d. ASE UTIL Page

The ASE UTIL page is accessible from the top level ASE page via the ASE UTIL page button. The ASE UTIL page contains functions used to configure the chaff system.

(1) ASE Utility page functions

(a) Chaff Safe/Arm button

Used to cycle the chaff system between safe and arm.

(b) Chaff MODE button

Used to select between the manual and program modes of the chaff system.

(c) CARTRIDGE count button

A data entry button that, in conjunction with the Keyboard Unit (KU), permits the crew to enter the number of chaff cartridges loaded in the dispenser payload module. The KU data entry prompt is “NN” and the valid data entry range is 0 - 30. Chaff cartridge quantities can also be entered via the LMP.

(d) Chaff BURST/SALVO Count/Interval Buttons

These multi-state option buttons provide the crew a means of configuring a chaff dispense sequence to be executed when the selected chaff mode is program and a cyclic chaff dispense switch is actioned.

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Figure 34. ASE UTIL Page Chaff Program Options 1

(e) BURST COUNT

Selects the number of chaff cartridges expended per burst. The available settings are 8, 6, 4, 3, 2, and 1 cartridges.

(f) BURST INTERVAL

Selects the interval in seconds between cartridges in a burst. The available settings are 0.4, 0.3, 0.2, and 0.1 seconds.

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Figure 35. ASE UTIL Page Chaff Program Options 2

(g) SALVO COUNT

1) Selects the number of bursts expended per program sequence.

2) The available settings are CONTINUOUS, 8, 4, 2, and 1 bursts. If CONTINUOUS is selected, the SP will dispense bursts of chaff cartridges until the chaff count reaches zero.

(h) SALVO INTERVAL

Selects the time in seconds between the last cartridge expended in the previous burst and the first cartridge expended in the following burst.

1) The available settings are 8, 5, 4, 3, 2, 1, and RANDOM.

2) The RANDOM selection cause the interval to vary from burst to burst in a pseudo random fashion based upon a factory preset sequence of 3, 5, 2, and then 4 seconds.

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Figure 36. Weapon (WPN) Page

e. Weapon (WPN) Page

The chaff cartridges count and chaff system Safe/Arm mode statuses are displayed in the aircraft silhouette icon. This information is displayed near the bottom of the icon to represent the approximate location of the CHAFF on the aircraft.

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Figure 37. Cyclic Stick Control Grip

f. Cyclic Grip

The dispensing of chaff cartridges can be manually initiated from either crewstation in both the manual and program modes. This is accomplished by depressing the red chaff dispense switch, located just below the Weapon Action Switch (WAS) on each cyclic grip.

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Figure 38. LMP

g. LMP

(1) The LMP is located in the right aft avionics bay and interfaces directly with the SP.

(a) The LMP is equipped with a keypad and a menu driven display

(b) It provides a means to load chaff cartridge count prior to a mission

(c) It displays the number of cartridges loaded in the SPs memory

(2) Selecting the ASE option (Option 5) from the LMP main menu displays the number of remaining chaff cartridges, as determined by the SP.

(a) It also permits personnel to enter the number of chaff cartridges loaded

(b) The valid data entry range is 0-30 cartridges

(c) The Escape (ESC) key is used to exit the ASE chaff count menu and return to the LMP main menu

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Figure 39. DMS DTU Page

h. DTC Programmable ASE Data

Chaff system parameters can be programmed into the system, via the DTC, as part of the miscellaneous data uploaded function, which is accessible on the DMS DTU page via the MISCELLANEOUS option. These parameters are as follows:

(1) Chaff dispense mode (manual or program)

(2) Chaff program mode parameters

(a) Burst count

(b) Burst interval

(c) Salvo count

(d) Salvo interval

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Figure 40. ASE and ASE UTIL Page

i. Subsystem Initialization


If system power-up occurs while the aircraft is on the ground (squat relay indicates on ground and both engine throttles in the Off/Stop position), the ASE subsystem selections are initialized to the default state. The system default values for the chaff system are listed below:

(a) Chaff Safe/Arm mode - safe

(b) Chaff dispense mode - program

(c) Chaff program mode parameters

1) Burst count - 4

2) Burst interval - 0.1

3) Salvo count - 1

4) Salvo interval - 1

(d) Chaff inventory - set to value stored during shutdown routine


If the power-up occurs while the aircraft is in the air, the ASE subsystem selections are initialized to the values stored at power-down.

j. Subsystem Shutdown

During the shutdown routine, the system saves the current value of chaff related parameters in non-volatile memory

(1) Chaff Safe/Arm mode

(2) Chaff dispense mode

(3) Chaff program mode parameters

(a) Burst count

(b) Burst interval

(c) Salvo count

(d) Salvo interval

(4) Chaff inventory

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Figure 41. DMS NAV/ASE and ASE Switch Test Advisory Pages

k. CHAFF System BIT

(1) The CHAFF system does not have BIT capability. The SPs provide limited BIT capability for the system.

(2) The ASE chaff switches can be tested for integrity via the SPs.

(3) Once the interactive IBIT is selected, the ASE switches test advisory page is presented with a warning displayed. This warning prompts the operator to ensure the safety pin is installed in the chaff safety switch on the tailboom prior to performing the test.

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Figure 42. ASE Switch Test and IBIT Listing Area Pages

(a) Once the safety step is accomplished and the acknowledge (ACK) button is selected, the chaff switch IBIT page is presented with the cyclic ASE switches test prompt displayed.

1) This prompt instructs the operator to action the chaff dispense switch on the cyclic grip.

2) During this time, the vertical “SWS” label, is displayed as OIP.

(b) Once the listed step(s) is/are completed and the ACK button is selected, bezel button label returns to normal video with a box and the IBIT listing area is displayed in the center of the page. The top line of the IBIT listing area is the test status line, which provides a status indication as to the progress of the IBIT.

1) Upon completion of the self-test, the message “TEST ENDED” is provided on the test status line.

2) If the ABORT button is selected at any time during the self-test, the SPs ignore any faults detected for that IBIT sequence, and the IBIT listing area displays “TEST ABORT” on the test status line.

(c) At the completion of the switch test, any faults detected by the SP are displayed in the IBIT listing area under the test status line.

1) Up to two pages of IBIT faults can be displayed if necessary.

2) If there are no failures detected during the switch test, the message “NO FAULTS FOUND” is displayed on the first line of the IBIT listing area, under the test status line.

(4) The chaff switch interactive IBIT is not executed if the ELC1 chaff arm/safe load controller is detected as failed, even though the IBIT selection is available when the failure exists. This fault will be displayed on the chaff switch IBIT page once the IBIT is initiated and completed.

(5) The chaff switches IBIT tests only the chaff dispense switches interface with the primary SP. To ensure that the switch interfaces are operational to both SPs, the IBIT must be performed twice; once with SP1 primary and again with SP2 primary.

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Figure 43. ASE Related Faults

l. Chaff BIT Status/Associated Faults

The DMS displays chaff related faults on the DMS page, DMS FAULT page, and/or ASE Switch IBIT pages if the associated failure has been detected during PBIT, CBIT, or IBIT

(1) SP 1/2 SRU 2 FAIL (SP 1/2 FAULT)

This fault indicates the primary SP has detected a fault within the discrete input module.


This fault indicates the primary SP has detected a fault within the discrete output module.

(3) ELC 1 Chaff ARM CONTROL FAIL (Chaff ARM CNTL)

This fault indicates ELC1 has failed load controller KD326-A1, which provides 28 Vdc chaff arm power to the CHAFF.

(4) PLT CYCLIC Chaff SWITCH FAIL

The pilot's cyclic stick grip chaff switch has failed the interactive BIT test with the primary SP.

(5) CPG CYCLIC Chaff SWITCH FAIL

The CPG's cyclic stick grip chaff switch has failed the interactive BIT test with the primary SP.

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Check On Learning

1. How many M1 chaff cartridges can the payload module accommodate at one time?

_________________________________________________________________

_________________________________________________________________

2. Where is the chaff safety switch located on the AH-64D aircraft?

_________________________________________________________________

_________________________________________________________________

3. What is the purpose of the AH-64D Chaff Dispenser (CHAFF) System?

_________________________________________________________________

_________________________________________________________________

4. What is displayed in the chaff status window?

_________________________________________________________________

_________________________________________________________________

5. How does the operator initiate chaff dispensing?

_________________________________________________________________

_________________________________________________________________

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E. Enabling Learning Objective 5


Action: Identify the characteristics of the AN/ALQ-144A(V)3 Infrared Jammer (IRJAM) Countermeasures Set.




Figure 44. The Electromagnetic Spectrum (EM)

a. AN/ALQ-144A(V)3 Infrared Jammer (IRJAM)

(1) EM spectrum

(a) Radiation is the emission (discharge) and diffusion (scattering) of rays of heat, light, electricity, or sound.

(b) Infrared (IR) is part of the EM radiation spectrum.

(c) In the EM spectrum, IR energy falls between the upper limit of microwaves and the lower limit of visible light.

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(d) The EM radiation spectrum classifies radiation according to length of the radiated rays. Because of the high frequencies of IR radiation, it is more convenient to use wavelength to identify the IR portion of the EM spectrum.

1) Gamma ray, shorter than 0.006 nanometers

2) X-ray, 0.006 to 5 nanometers

3) Ultraviolet, 5 nanometers to 0.4 micrometers

4) Visible light, 0.4 to 0.7 micrometers

5) Infrared, 7 micrometers to 1 millimeters

6) Radio frequency, 1 millimeters

(e) Nature of IR

Warm objects emit IR radiation and the temperature of the object dictates the characteristics of the radiation.

1) As the temperature of the materials increases, the overall bandwidth of the radiation and the radiant intensity increases.

2) Also, as the temperature increases, the peak energy intensity shifts to shorter and shorter wavelengths and faster oscillation (higher frequency). Thus, wavelength is proportional to temperature.

3) Some examples of emitters of IR emission are:

a) Aircraft

b) Wheel and track vehicles

c) Weapons

d) Manmade structures (buildings, bridges, and radio or TV towers)

e) People

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Figure 45. Aircraft Sources of IR Radiation

b. Aircraft Sources of IR Radiation

IR signature is the radiation given off by an object (emitter or source). There are three classes or sources of IR radiation emitted from aircraft.

(1) Sunlight (class I) radiation is sun reflected off the metal skin of an aircraft or like object.

(2) Hot metal surfaces (class II) originate primarily from hot engine components.

(3) Hot exhaust gases (class III) are emitted by the hot exhaust gas plume which trails behind the engine exhaust nozzle. This is the major contributor to the IR signature of an aircraft. Therefore, most attacks from IR missiles occur from the rear.

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Figure 46. FIM-92A Stinger (U.S.) and SA-18 Grouse (Soviet counterpart)

c. Antiaircraft IR System Principles.

(1) These systems are compact, fired by one person from a disposable launch tube.

(2) The warhead weighs about 11 pounds.

(3) During the Vietnam conflict, many aircraft were damaged or destroyed with similar systems.

(4) Compared to a radar system, IR systems are smaller, less expensive and more accurate.

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Figure 47. Subsystems of an IR Missile Guidance System

d. IR Missile Guidance System.

(1) The rotating telescope (seeker head) collects IR radiation and focuses it on a rotary disc.

(2) The reticle (rotary disc/modulator) is the most important component in an IR missile.

(a) It modulates and encodes the IR to get target position information.

(b) This allows the missile to discriminate between real and false targets.

(c) It passes target information to detector.

(3) The IR detector converts the information passed by the reticle into an electrical signal.

(4) The missile electronics and amplifier amplify the signal and feed it to a guidance processor. This makes the seeker head turn towards the target.

(5) The guidance processor uses the signal to drive wings called canards. It attempts to steer the missile to a collision course with target.

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Figure 48. Passive Countermeasure Techniques

e. Countermeasure Techniques

There are two types of IR countermeasure techniques employed on most aircraft today. These are passive and active techniques.

(1) Passive

(a) Passive techniques reduce the aircraft’s IR signature and active techniques decoy or deceive the incoming threat.

(b) Passive techniques shield hot parts of an aircraft that reduces its infrared radiation.

(c) The aircraft may incorporate on its fuselage and wings anti-reflective paint that is dull and spreads out the sun's radiation.

(d) Exhaust suppressors mix cool air with engine exhaust to reduce the exhaust plume gases temperature.

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Figure 49. Active Countermeasure Techniques

(2) Active techniques decoy or deceive IR missiles.

(a) The M141 flare dispenser set is a decoy countermeasure set. Flares were the first active IR countermeasures employed on army aircraft.

(b) Their intense IR source actually decoyed missiles away from the aircraft.

(c) These flares worked well, but their effectiveness depended upon knowing when a missile was coming.

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Figure 50. Deceptive Countermeasure

(d) Deceptive countermeasures (jammers) like the AN/ALQ-144A(V)3 was designed to confuse a missile’s guidance system by emitting false target information.

(e) It consists of a very intense IR source and a system to modulate the IR energy.

(f) The source is a hermetically sealed element heated to a temperature higher than any part of the aircraft.

(g) The IR radiation is then modulated by spinning optical elements that generate IR energy that deceive or confuse the missile.

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Figure 51. T-1360A(V)1/ALQ-144(V) IRJAM Transmitter

f. The AN/ALQ-144A(V)3 IRJAM

(1) The AN/ALQ-144A(V)3 IRJAM is an active IR countermeasure set that operates as an IR transmitter to jam heat-seeking IR missiles.

(2) The IR signal generated by the IRJAM is strong enough to make the seeker of an IR missile look in the wrong direction or become saturated with false information. This causes the missile to fail to make the required maneuvers to intercept the target.

(3) The IRJAM transmitter is mounted on the top of the aircraft, just aft of the main rotor mast.

(4) The AN/ALQ-144A(V)3 is a continuously operating, omni-directional, electrically fired IRJAM system.

(5) The system consists of the T-1360A(V)1/ALQ-144(V) IR jammer transmitter.

(a) The transmitter requires a one-minute warm-up period prior to assuming normal operation.

(b) The transmitter generates IR energy, modulates it, and then passes it through the covert window in the form of invisible IR energy.

(c) The covert windows block the transmission of unwanted wavelengths of EM energy, such as visible light.

(6) The radiation is modulated mechanically at low and high frequencies in fixed or sweep mode of operation.

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(7) The IRJAM transmitter consists of the following:

(a) IR source

1) The IR source is comprised of a heating element that is hermetically sealed in a glass envelope.

2) Using the 28 Vdc input, the IR source produces/creates a tremendous amount of heat to provide invisible IR energy.

(b) Covert window

1) The covert window contains 36 germanium coated glass panes mounted in three rows. The windows are transparent to IR energy, but are opaque to visible light.

2) The covert windows spread the IR energy.

(8) The IRJAM is equipped with the following switches and indicators, which can be accessed, and observed when the BIT indicator panel access cover is removed from the transmitter.

(a) High Frequency (HF) and Low Frequency (LF) BIT indicators

1) For proper countermeasure operations, the high and low speed modulators must maintain a precise reference signal. If the control circuits cannot maintain normal modulator speed, a HF or LF BIT indicator will be set.

2) The BIT indicator is latched when the control circuitry output is beyond preset limits. At the same time, the inoperative (INOP) circuit is activated which shuts down the transmitter.

(b) Emission (EM) BIT indicator

1) Circuits located inside the transmitter continuously compare the IR source output signal with a fixed reference. If the IR radiation level of the source drops below its normal range, the EM BIT indicator is latched, indicating that the IR emission is out of tolerance.

2) When the EM BIT indicator latches, a signal is sent to the INOP circuit, which shut down the transmitter.

(c) High Temperature (HT) BIT indicator

1) During normal operation, the transmitter blower forces cooling air over the components to keep them within their normal temperature limits.

2) If the cooling air flow stops or is reduced for some reason, the components exceed their normal temperature limits. If overheating occurs, internal signals latch the HT BIT indicator.

3) When overheating occurs, a signal is sent to the INOP circuit, which shut down the transmitter for as long as the over temperature condition exists.

(d) Reset/Fixed/Swept (RST/FXD/SWP) switch

1) Allows the operator to reset the BIT indicators (RST), select fixed (FXD) frequency mode of operation, and select sweep (SWP) frequency mode of operation.

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2) After using this switch to reset the BIT indicators, ensure that the switch is set to the required jam program mode (FXD or SWP).

(e) Jam program selector switch

Positioning of this switch selects the jam program for transmitter operation.

(f) Jam program indicator

This indicator displays the selected jam program through an opening in the wall of the card cage.

(g) Elapsed time indicator

This indicator monitors the operation time of the unit and provides a digital readout in hours.

(9) The covert window assembly is very hot during and immediately after transmitter operation. Keep hands and other parts of the body away from this area. Allow the transmitter to cool for at least 15 minutes prior to removal.

(10) Caution should be exercised while working in the vicinity of the transmitter anytime it is operating.

(a) Due to the large amount of IR radiated from the transmitter, caution should be exercised to prevent exposure of skin or eyes at distances less than three feet.

(b) Prolonged viewing of the IRJAM from less than one foot may cause eye damage.

(c) Do not view the unit in excess of one minute when located within three feet of the unit. IR radiation effects may be cumulative.

(d) Hearing damage may also occur due to the mechanical modulation frequencies employed in the transmitter.

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Figure 52. ASE Page

g. ASE Page

(1) The ASE page provides for the control of the IRJAM system and the display of related mode and status indications.


(a) IRJAM On/Off button

Used to power the IRJAM on and off. When initially powered on, the IRJAM executes a one minute warm-up period before transitioning into normal operation with little, if any, IR radiation coming from the IRJAM during the warm-up period.

1) This warm-up period is a function of the IRJAM. However, the status of the jammer is reported back to the SP via a discrete signal and is then indicated on the ASE page within the IRJAM status window.

2) The button legend is removed from the display if the IRJAM is not installed in the aircraft.

(b) IRJAM status window

Provides an indication of the current status of the IRJAM with statuses of warm-up (WARM) and operate (OPER) available for display.

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1) During the warm-up period, the displayed status of the IRJAM will be WARM and will change to OPER when the IRJAM transitions to the operate mode.

2) The IRJAM status window is removed from the display whenever the IRJAM is selected off.

Figure 53. ASE Related Cautions

h. IRJAM Related Warnings/Cautions/Advisories (WCAs)

(1) Warnings

There are no IRJAM related aircraft warnings displayed in the crewstations.

(2) Cautions: IRJAM FAIL

(a) This caution indicates that the SP has detected an IRJAM failure while the IRJAM is powered on.

(b) The SP monitors the IRJAM INOP discrete for an IRJAM failure whenever the IRJAM is powered on.

(3) Advisories

There are no IRJAM related aircraft advisories displayed in the crewstations.

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Figure 54. ASE and ASE UTIL Pages

i. Subsystem Initialization and Shutdown


If system power-up occurs while the aircraft is in an "on ground" condition (squat switch indicates on ground and both throttles are in the Off/Stop position), the IRJAM subsystem On/Off selection is initialized to the default state which is IRJAM Off.


If the power-up occurs while the aircraft is in an “in air” condition, the IRJAM subsystem On/Off selection is initialized to the value stored at power-down.

(3) Subsystem shutdown

During the shutdown routine, the system saves the current value of the IRJAM On/Off selection in non-volatile memory.


j. AN/ALQ-144A(V)3 IRJAM System BIT

(1) The IRJAM transmitter performs CBIT while it is operating and reports any failures to the SPs via a discrete input. The exact nature of the failure is not provided in the crewstation, but can be discerned by removing the BIT indicator panel and viewing the four BIT indicators that are located on the unit itself.

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(2) The SPs also monitor the load controller status from ELC2 to determine if a load controller fault exists when IRJAM power is commanded on and off.

(3) When power is initially applied to the IRJAM, the INOP circuitry within the transmitter is inhibited to allow the unit time to warm-up.

(a) This is done to prevent the transmitter from shutting down since the source output and the modulator speeds are abnormal during the warm-up period.

(b) After the warm-up period is complete, the BIT inhibit signal is removed and the INOP circuit is enabled.

(c) This allows the BIT indicator to detect faults, placing the transmitter into an inoperative state should a fault occur.

k. AN/ALQ-144A(V)3 IRJAM BIT Status/Associated Faults

The DMS presents the following IRJAM related faults on the DMS page and DMS FAULT page as a result of CBIT detected failures:


(a) This fault indicates that the primary SP has detected a fault within the discrete input module.

(b) Since the primary SP receives discrete signals from the IRJAM system, this fault can influence an IRJAM failure.

(2) ELC 2 IR JAMMER CONTROL FAIL (IR JAMR PWR CNTL)

(a) This fault indicates that ELC2 has failed load controller SD491-C1 that provides a ground to the IRJAM internal 28 Vdc power on relay.

(b) If this load controller fails, the IRJAM system cannot be powered up or powered down.

(3) INFRARED JAMMER FAIL (IR JAMMER FAIL)

(a) This fault indicates that the IRJAM has internally detected a failure.

(b) The SP monitors the IRJAM inoperable discrete for an IRJAM failure when the IRJAM is powered on.

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Check On Learning

1. Where can the Infrared Jammer (IRJAM) system be turned on/off?

_________________________________________________________________

_________________________________________________________________

2. How long is the warm-up period for the IRJAM transmitter prior to transitioning to the operate mode?

_________________________________________________________________

_________________________________________________________________

3. What is the purpose of the AN/ALQ-144A(V)3 IRJAM?

_________________________________________________________________

_________________________________________________________________

4. What is the minimum safe distance to be maintained from the IRJAM transmitter to prevent over exposure to the skin and eyes?

_________________________________________________________________

_________________________________________________________________

5. If an IRJAM Continuous Built In Test (CBIT) failure is detected, where can the exact nature of the fault be discerned?

_________________________________________________________________

_________________________________________________________________

NOTES

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D-83

F. Enabling Learning Objective 6


Action: Identify the characteristics of the AN/ALQ-136(V)5 Radar Jammer (RJAM) Countermeasures Set components.




a. Early Jamming

(1) Jamming is the interference with or the prevention of clear reception by electronic means. Until the 20th century, when radio and radar became widely used, there was no need to electronically "jam" signals.

(2) The Voice of America was established in 1942 to promote a favorable understanding of the United States through an international radio network (107 transmitters around the world). It was the victim of the largest jamming of any broadcast signals when the USSR and its satellites attempted to jam the Voice of America broadcasts directed to communist countries between 1948 and 1963 and again between 1968 and 1973.

b. Radar Jamming

(1) Radar, which can provide information on the type, range, and bearing of aircraft, has characteristics that make an aircraft vulnerable to detection. Therefore a form of ECM needed to be developed to protect our aircraft.

(2) The AN/ALQ-136(V)5 is a radar jammer. The actual operation of the AN/ALQ-136(V)5 is classified, but radar jammers are a form of ECM in which interfering signals, typically noise-like, are transmitted at frequencies in the receiving band of radar to obscure or distort the radar signal.

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Figure 56. AN/ALQ-136(V)5 RJAM Components

c. AN/ALQ-136(V)5 RJAM

The AN/ALQ-136(V)5 RJAM is an active ECM system designed to protect the aircraft against certain AAA and SAM threats.

(1) The RJAM system is a self-contained system that receives, detects, analyzes, and processes those pulse radar signals usually associated with hostile FCRs. The system initiates the appropriate jamming signals in an attempt to effectively counter the detected threats.

(2) The RJAM system is a pulse radar jammer only, and does not accommodate the detection or jamming of Continuous Wave (CW) radar systems.

(3) The RJAM system consists of a R/T and two antennas; one antenna is used for reception and one antenna is used for transmission.

d. Major System Components

(1) RJAM Receiver/Transmitter RT-1149(V)5/ALQ-136(V)

(a) The RJAM R/T accepts RF signals from the RJAM receive antenna, processes those signals to determine the existence of a pulse radar threat, and generates appropriate jamming signals that it applies to the RJAM transmit antenna for propagation.

(b) The AN/ALQ-136(V)5 R/T is located in the forward portion of the left EFAB. It is mounted upside down, facing forward, below the top shelf.

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(2) RJAM receive antenna AS-3710/ALQ-136(V)

(a) The RJAM receive antenna provides forward sector reception of RF signals in the appropriate frequency range and applies them to the RJAM R/T for processing.

(b) The RJAM receive antenna is mounted on the forward edge of the doghouse fairing, just above and behind the pilot's head.

(3) RJAM transmit antenna AS-3711/ALQ-136(V)

(a) The RJAM transmit antenna radiates RFJAM signals in the forward sector to counter certain enemy threat radar systems.

(b) The RJAM transmit antenna is mounted on the Aircraft Interface Assembly (AIA) to the left of center, facing forward.

(4) RJAM transmit and receive antenna coaxial cables

(a) The cables utilized to transfer RF between the RJAM R/T and the system antennas are special, low-loss, rigid coaxial cables. They are considered system Line Replaceable Units (LRUs) with no repair authorized at the AVUM level.

(b) Should a cable malfunction occur, that cable must be removed and replaced with an operational cable.

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Figure 57. RT-1149(V)5/ALQ-136(V) RJAM R/T

e. Component Characteristics

(1) RJAM R/T RT-1149(V)5/ALQ-136(V)

(a) The RJAM R/T performs all the basic functions of electronic RF countermeasures.

(b) Radar signals received from the receive antenna are sorted and analyzed for key parameters such as amplitude, modulation, PRI, and radio frequency.

(c) The measured parameters are compared to those of known threat radar parameters stored in the R/T’s memory.

(d) When a signal is identified as a threat, the appropriate countermeasures signal is automatically generated and sent to the transmit antenna for radiation.

(e) The RJAM R/T WAR/TNG switch is a lever-locked, two-position switch that is safety wired in the desired position. This switch and the associated capability are part of the “Quiet Camp” modification performed on the RJAM R/Ts.

1) In a wartime environment, the switch is safety wired in the WAR position. With WAR selected, the system provides full-up operational capability to include complete frequency band coverage, operational ECM programs, and actual jamming signals.

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2) In a training environment, the switch is safety wired in the Training (TNG) position. With TNG selected, the system provides very limited frequency band coverage; utilizes non-operational test programs; and generates unclassified, non-operational jamming signals. The primary purpose of the training mode is to exercise the system in a peacetime environment without compromising its actual operational capability, which is classified. Use of the system in the training mode is encouraged periodically to ensure system operation.

Figure 58. AN/ALQ-136(V)5 RJAM Receive and Transmit Antennas

(2) RJAM receive antenna AS-3710/ALQ-136(V)

(a) The receive antenna is a coaxial cable-fed horn antenna with a protective radome mounted over it.

(b) The antenna is circular polarized and is designed to provide the necessary spatial coverage for effective countermeasures against certain threat radars. The gain of the receive antenna contributes to the overall system receiver sensitivity.

(c) It receives pulse radar signals in the appropriate frequency range (currently classified) and supplies them to the RJAM R/T.

(3) RJAM transmit antenna AS-3711/ALQ-136(V)

(a) The transmit antenna is a coaxial cable fed horn antenna with a protective radome mounted over it.

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(b) The antenna is circular polarized and is designed to provide the necessary spatial coverage for effective countermeasures against certain threat radars. The gain of the transmit antenna contributes to the overall Effective Radiated Power (ERP) of the system.

(c) It transmits modulated pulse radar jamming signals in the appropriate frequency range (currently classified) supplied by the RJAM R/T.

f. Threat Detection and Jamming

(1) The system performs effectively as both a detection system and a jamming system for pulse radar threats.

(a) The receive antenna receives pulse radar signals and supplies them to the R/T receiver circuits via a special low-loss coaxial cable.

(b) The receiver processes this RF energy and extracts the video (pulses) from it.

(2) To detect threats, the RJAM R/T continuously executes a scan of the operating high band frequency range (currently classified).

(a) This scan is performed in a predetermined number of scan windows that are initially of a set bandpass.

(b) The receiver starts at the bottom of the frequency range and scans through the range in these large bandpass windows until it completely cycles through the entire range.

(3) When the system detects RF in one of these large scan windows, it splits the large window into smaller scan windows and scans through the smaller windows to determine in which window the RF is sensed.

(4) The system continues this process for all received signals until center frequency resolution is achieved.

(5) Once the system begins jamming a threat(s) and the next high band scan is initiated, the system employs a “look-through” scheme to determine if the threat is still radiating.

(6) This is accomplished by applying a blanking signal to the transmitter while the receiver “looks” at the frequency band in which the threat was operating.

(a) If the threat is still radiating on the same frequency, the system will continue to jam the threat on the currently tuned frequency.

(b) If the threat is frequency agile and has changed operating frequency, the system will detect the new frequency and commence jamming on that frequency.

(c) If the threat is no longer radiating, the system ceases jamming that threat.

(7) This video is filtered, limited, amplified, and detected, and provided to the processor section of the R/T for analysis.

(8) The processor compares the resultant video with the stored threat signal parameters to determine whether the received signal originated from a threat. These signal parameters include:

(a) PW

(b) Pulse spacing

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(c) PRI

(d) Signal strength

(e) Scan type

(f) Modulation type

(g) Center frequency

(9) If a threat exists, the processor queries the stored jamming parameters table for the appropriate jamming profile. If one exists, the jamming parameters are extracted, to include center frequency, modulation type, and jamming technique, and sent to the transmitter section.

(10) The transmitter section generates the appropriate jamming signals and applies them to the transmit antenna for radiation via another low-loss coaxial cable.

(a) The system can detect, process, and jam multiple threats in a multiplex fashion using one set of antennas.

(b) Current system configuration only provides for forward sector coverage for

pulse radar threats.

(11) The AN/ALQ-136(V)5 system poses a potential RF radiation hazard to personnel due to the operating frequency range and transmitter output power.

(a) When the system is powered up, personnel should remain clear of the transmit antenna by a minimum of 10 feet to prevent overexposure to high frequency RF radiation and the corresponding effects.

(b) The system radiates during self-test (at a reduced power setting) and when stimulated by a threat signal while in the operate mode.

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Figure 59. ASE Page

g. ASE Page

(1) The ASE page provides for the control of the RJAM system and the display of related mode and status indications.


(a) RJAM grouped options

Used to provide the crew with a means of selecting the RJAM modes of OFF, standby (STBY), or operate (OPER). The system is powered on by selecting either the standby or operate modes.

1) The RJAM modes of operation are delineated as follows:

a) OFF

The system is powered down.

b) STBY

The RJAM transmitter is inhibited from radiating and thus, is unable to perform any jamming operations. After the three-minute warm-up period, however, the unit is ready for operation and will perform as a threat detection system.

c) OPER

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The transmitter is no longer inhibited. The system will not only detect and process threats, but will also respond by generating the appropriate jamming signals to counter existing threats.

2) The radar jammer requires a three minute warm-up period in the standby mode prior to entering the operate mode.

a) When selecting the RJAM from off direct to operate, the RJAM will enter the standby mode for the three-minute warm-up period.

b) During this time, the STBY legend will be displayed as Operation In Progress (OIP) and, at the end of the three minutes, the system will automatically transition to operate.

3) When it is turned on via the ASE page and warmed up, the RJAM can also be moded between standby and operate on the TSD page.

4) When the radar jammer is actively jamming, the radar jammer icon is displayed as a cyan (greenish-blue) flashing lightning bolt in the center of the cyan ownship symbol on the ASE and TSD pages. This indication is accompanied by a RDR JAM ON advisory displayed on the UFD.

5) These button legends and the associated group bracket are removed from the display if the RJAM receiver/transmitter is not installed.

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Figure 60. TSD Page

(3) The RJAM can be moded between standby and operate on the TSD page via the JAM option. The JAM option is a maintained option button whose label only appears if the RJAM system is moded to on via the ASE page.

(a) Once the system is powered on, the JAM label is displayed and, after the initial three-minute warm-up period is complete, the RJAM can then be toggled between standby and operate modes with subsequent selections of the button.

(b) The JAM label displayed without box indicates that the RJAM system is in standby mode while the JAM label displayed within a box (maintained option convention) indicates that the system is in the operate mode.

TSD Page

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Figure 61. ASE Cautions

h. RJAM Related Warnings/Cautions/Advisories (WCAs)

(1) Warnings

There are no RJAM-related aircraft warnings displayed in the crewstations.

(2) Cautions

RJAM FAIL

This caution indicates that the SP has detected a RJAM failure while the jammer is in the operate mode. The SP monitors the RJAM circuit breaker for closure, and monitors the RJAM Traveling Wave Tube Assembly (TWTA) fault indication when the RJAM is powered on.

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Figure 62. ASE Advisories

(3) Advisories

(a) RJAM FAIL

This advisory indicates that the SP has detected a RJAM failure while the jammer is in the standby mode. The SP monitors the RJAM circuit breaker to see if it closed and the RJAM TWTA fault indication when the RJAM is powered on.

(b) RDR JAM ON

This advisory indicates that the RJAM is actively jamming a detected threat or threats.

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Figure 63. ASE and ASE UTIL Pages

i. Subsystem initialization


If system power-up occurs while the aircraft is in an "on ground" condition (squat switch indicates on ground and both throttles are in the Off/Stop position), the RJAM subsystem selections are initialized to a default state. The system default values are listed below:

(a) RJAM mode - off

(b) RJAM self-test mode - off


(a) If the power-up occurs while the aircraft is in an “in air” condition, the RJAM subsystem selections are initialized to the values stored at power-down.

(b) If the saved value of the RJAM mode is operate, the RJAM goes into a standby mode for the initial three-minute warm-up period as discussed previously. After three minutes the RJAM transitions back to operate mode.

j. Subsystem shutdown

During the shutdown routine, the system saves the current value of the following RJAM subsystem parameters in non-volatile memory:

(1) RJAM mode

(2) RJAM self-test mode

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Figure 64. DMS NAV/ASE and RJAM IBIT Pages

k. AN/ALQ-136(V)5 RJAM system BIT

The RJAM system has two types of BIT capability:

(1) CBIT

During normal operation, the R/T performs CBIT to determine system status.

(a) The R/T checks critical parameters within the TWTA and checks the integrity of the transmit antenna and the respective coaxial cable while the system is transmitting.

(b) These checks are performed in the background so as not to interfere with normal system operation.

(c) The R/T reports detected system failures to the SP for display on the MPD.

(2) IBIT

The IBIT provides a more detailed test of the system to include transmissions, at a reduced output power, to check transmitter operation and the transmit antenna/coaxial cable for Voltage Standing Wave Ratio (VSWR).

(a) The IBIT routine exercises the system as though actual threat signals are being received.

(b) The receive antenna and coaxial cable are not tested.

(c) IBIT takes precedence over normal operation and, when initiated, will interrupt/suspend normal system operation for approximately seven seconds.

(3) The IBIT can be performed via the NAV/ASE IBIT page by selecting RJAM.

(a) RJAM IBIT can only be selected and executed with the RJAM system in the operate mode.

(b) The RJAM IBIT button legend is removed from the display if the RJAM R/T is not installed.

(c) The RJAM IBIT selection is displayed with a non-selectable barrier if the RJAM system is powered off or is powered on and moded to standby.

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(4) At the completion of the self-test, any faults detected and reported to the SPs by the RJAM R/T are displayed in the IBIT listing area under the test status line.

(a) Up to two pages of IBIT faults can be displayed.

(b) If no faults are detected during the self-test, the message “NO FAULTS FOUND” is displayed on the first line of the IBIT listing area, under the test status line.

(5) Although the RJAM has a reasonably thorough BIT capability, the BIT is not an end-to-end test of the system.

(a) The receive antenna and the associated coaxial cable are not tested at all during system BIT.

(b) In fact, the receive antenna and its cable can be completely disconnected from the RJAM R/T and the system will pass both the CBIT and IBIT routines.

(c) The transmit antenna and its associated coaxial cable are tested during transmissions as a function of both CBIT and IBIT.

(6) The only true method of end-to-end testing of the system is to utilize the TS-3614/ALQ-136(V) Flight Line Test Set (FLTS) to stimulate the system and verify a corresponding response.

(a) The FLTS radiates the receive antenna with certain simulated threat radar signals and verifies that the system generates and radiates a jamming signal from the transmit antenna.

(b) This also allows the operator to verify the appropriate visual and audible indications in the crewstations.


l. AN/ALQ-136(V)5 RJAM BIT status/associated faults

The DMS presents the following RJAM-related faults on the DMS page, DMS FAULT page, and/or RJAM IBIT page if the associated failure has been detected during either PBIT, CBIT, or IBIT.


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(a) This fault indicates that the primary SP has detected a fault within the analog I/O module.

(b) Since the primary SP receives analog signals from the RJAM system, this fault can influence a RJAM failure.


(a) This fault indicates that the primary SP has detected a fault within the discrete input module.

(b) Since the primary SP receives discrete signals from the RJAM system, this fault can influence a RJAM failure.


(a) This fault indicates that the primary SP has detected a fault within the discrete output module.

(b) Since the primary SP commands discrete signals to the RJAM system, this fault can influence a RJAM failure.

(4) ELC 2 RADAR JAMMER CONTROL FAIL (RDR JAMR PWR CNTL)

ELC2 has lost control of RJAM power control.

(5) RADAR JAMMER TWTA FAULT (RADAR JAM FAULT)

(a) This fault indicates that the RJAM traveling wave tube assembly has failed.

(b) The SP monitors the TWTA fault discrete input when the RJAM is powered on.

(6) RADAR JAMMER CKT BRKR FAULT (RADAR JAM FAULT)

(a) This fault indicates that the RJAM circuit breaker is not closed properly.

(b) The SP monitors the circuit breaker fault discrete input when the RJAM is powered on.

(7) RADAR JAMMER POWER FAULT (RADAR JAM FAULT)

(a) This fault indicates that the RJAM circuit breaker is not open properly.

(b) The SP monitors the RJAM power fault when the RJAM is powered off.

(8) RADAR JAMMER NO-GO FAULT (RADAR JAM FAULT

(a) This fault indicates that the RJAM has failed self-test.

(b) The SP monitors the RJAM GO and NO-GO indication discrete inputs only during RJAM IBIT and thus, this fault is only displayed on the RJAM IBIT page.

(9) RADAR JAMMER FAIL (RADAR JAM FAULT)

(a) This fault indicates that the RJAM has failed to enter or exit self-test properly.

(b) The SP monitors the RJAM self-test discrete input only during RJAM IBIT and thus, this fault is only displayed on the RJAM IBIT page.

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Check On Learning

1. Where is the Radar Jammer (RJAM) transmit antenna located and in what sector(s) do/does it

provide jamming coverage?

_________________________________________________________________

_________________________________________________________________

2. The transmit antenna provides jamming coverage in which sector?

_________________________________________________________________

_________________________________________________________________

3. How long is the warm-up period for the RJAM prior to entering the operate mode?

_________________________________________________________________

_________________________________________________________________

4. How does the operator know that the RJAM is actively jamming a detected threat in the operate mode?

_________________________________________________________________

_________________________________________________________________

5. While the RJAM system is radiating, what is the minimum safe distance to be maintained from the RJAM transmit antenna to prevent possible overexposure to high frequency RF radiation?

_________________________________________________________________

_________________________________________________________________

NOTES

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G. Enabling Learning Objective 7


Action: Identify the characteristics of the AN/APR-48A Radar Frequency Interferometer (RFI) System.

Conditions: Given a written test without use of student notes or references.



Figure 66. AN/APR-48A Radar Frequency Interferometer (RFI) Components

a. AN/APR-48A Radar Frequency Interferometer (RFI)

(1) The RFI is a passive Electronic Support Measure (ESM) system that provides detection, acquisition, identification, classification, location, and prioritization of radar emitters.

(2) The system detects and processes Pulse, Pulse Doppler, and Continuous Wave (CW) radar signals, which operate in a currently classified frequency range.

(3) The RFI is an offensive system that provides narrow FOV target cueing for onboard and offboard sights/sensors for employment of weapons.

(4) It also supplies highly effective defensive threat warning capability for the ASE suite.

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(5) The high sensitivity of the system provides main beam signal detection and sidelobe and/or backlobe signal detection.

(6) The system is designed to detect Low Probability of Intercept (LPI) signals and to detect the threat before it detects the aircraft.

(7) It is capable of threat acquisition well beyond threat lethal range. Due to the mounting location above the rotor mast, it also provides masked detection of threats.

(8) The RFI provides 360° coverage about the aircraft for coarse Direction Finding (DF) and instantaneous 90º coverage for precision fine DF.

(9) The coarse DF routine employs amplitude DF techniques, and utilizes four coarse DF antenna elements. The coarse antenna elements compare the amplitude of adjacent antenna channels to determine signal AOA.

(10) The system utilizes a three-antenna baseline for the phase interferometer to perform the accurate fine DF routine.

(11) The system performs accurate parametric data measurement for precise, unambiguous, identification and classification of detected emitters. The threat parametric data scrutinized by the processor for detected signals includes:

(a) Frequency

(b) Bandwidth

(c) Pulse Repetition Interval (PRI)

(d) Pulse Width (PW)

(e) Pulse Spacing (PS)

(f) Scan type

(g) Scan rate

(h) Time In Main Beam (TIMB)

(12) The identification processing allows for processing of multi-beam emitters that output more than one type of RF signal simultaneously or on a time scheduled basis.

(a) The RFI correlates these signals so that only one threat ID is displayed on the MPD.

(b) The threat is displayed with its corresponding mode information (search, acquisition, track, lock-on/launch, etc.).

(c) The sophisticated signal processing allows the detection and identification of frequency and PRI agile emitters.

(13) The RFI system employs a UDM, which is mounted in the face of the RFI processor.

(a) It contains the classified portion of the operational software, a Dwell Sequence Monitor Table (DSMT), and an Emitter ID Table (EIDT).

(b) The DSMT controls the sequence of RF band monitoring.

(c) Each entry in the table contains a frequency band at which to dwell, a length of time in which to dwell, and the number of sort windows.

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(d) The EIDT accommodates 100 threat entries with each entry containing the following information:

1) RF, PRI, Sigma PRI, PW limits (eight specific parameters)

2) Parametric volume (ambiguity resolver)

3) Identification code

4) Priority

5) Flags to include: hostile/friendly, airborne, CW, etc.

6) Mode

7) Lethal range

Figure 67. RFI Processor

b. Major system components

(1) RFI Processor (MX-10860A/APR-48A)

(a) The Radar Target Data Processor is the heart of the RFI system.

(b) It accepts 28 Vdc aircraft power from HPSM1 and provides the required operating voltages for the system.

(c) It performs the threat processing and reporting functions, and executes BIT and calibration routines for the system.

(d) The RFI processor is located in the aft portion of the left EFAB.

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(e) It is situated just aft of the FCR PSP with which it normally directly interfaces for operation.

(f) The RFI processor front panel contains a carrying handle, inductive cooling fan, Elapsed Time Indicator (ETI) meter (M1), UDM.

Figure 68. RFI Receiver

(2) Radar receiver (RFI receiver) (R-2367A/APR-48A)

(a) The RFI receiver accepts four Intermediate Frequency (IF) inputs from the antenna assembly.

(b) It processes the information contained in these four inputs and translates the data into a pulse descriptor word that is provided to the RFI processor for threat processing.

(c) The RFI receiver is mounted below the MMA on the MMA pedestal.

(d) It is located above the rotor mast and is oriented 180° out from the antenna assembly.

(e) The aft coarse DF antenna is mounted on the rear surface of the RFI receiver. It receives RF energy in the 90° rear quadrant and sends it to the antenna assembly.

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Figure 69. RFI Antenna Assembly

(3) Antenna assembly (AS-4268/APR-48A)

(a) The antenna assembly performs the RF receiving function for the system.

(b) It receives RF energy in the appropriate frequency bands, down converts RF into IF signals, and provides four channels of IF to the RFI receiver.

(c) The antenna assembly is mounted above the rotor mast on the MMA pedestal, below the MMA.

(d) It is oriented to be coincident with the MMA antenna/radome.

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Figure 70. AS-4268/APR-48A Antenna Assembly

(e) The antenna assembly consists of an ETI meter (M1) and the following seven antenna elements:

1) Right coarse DF antenna

2) Very long baseline antenna

3) On-signal calibration antenna

4) Long baseline antenna

5) Forward coarse DF/short baseline antenna

6) Fine DF reference antenna

7) Left coarse DF antenna

(f) Functional description

1) The antenna assembly consists of two array sets which are used to receive RF signals: a coarse DF array and a fine DF interferometer array.

a) An additional antenna sensor, the On-Signal Calibration (OSC) antenna, is used for internal calibration.

b) Identical spiral sensors are used for the coarse and fine DF arrays, along with the on-signal calibration sensor.

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c) The fine DF array uses a matched set of sensors within the antenna assembly.

2) The coarse DF array provides 360° coverage with four antenna sensors, forward, left, right, and aft.

a) Three of the antennas are pointed 90° apart on the antenna assembly.

b) The fourth antenna (aft) sensor is located on the RFI receiver.

c) Each antenna can be switched to its dedicated RF channel by the front end RF switch located on the RF assembly in the antenna assembly.

d) The incoming RF signals are converted to IF in the RF assemblies.

e) The IF signals are passed to the RFI receiver for amplitude-based DF measurements.

f) The system operates with an IF bandwidth of 175 MHz.

3) The fine DF phase array consists of a four element, three-baseline interferometer with short, long, and very long baselines.

a) The phase antennas are switched to the forward, left, and right channels for IF processing and subsequent phase measurement by the RFI receiver.

b) The right channel is the reference channel for phase measurements, and the reference antenna is switched to that channel.

4) The short phase antenna (also the forward channel for coarse DF measurements) is switched into the forward channel for phase measurements.

a) Another switch setting allows the very long phase antenna to be switched into the forward channel for phase measurements.

b) The long phase antenna is switched into the left channel for phase measurements.

5) Depending on the switching selected by the RFI processor, the RFI receiver can measure the phase difference between the reference-short and reference-long baselines simultaneously, or, can measure reference-long and reference-very long baselines simultaneously.

6) Internal to the antenna assembly is a BIT/Cal assembly.

a) In one mode, the BIT/Cal assembly is used as an internal RF source to calibrate and test the system by generating a series of combine frequencies covering the system frequency range.

b) In the other mode, the BIT/Cal assembly receives incoming signals from the on-signal calibration antenna.

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Figure 71. Blade Position Indicator Assembly (BPIA)

(4) Blade Position Indicator Assembly (BPIA)

(a) The BPIA sends rotor blade strobe signals to the SPs, FCR PSP, and the RFI processor.

(b) These strobe signals provide an indication of rotor blade position.

(c) This information is necessary to prevent rotor blade interference with the systems.

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Figure 72. ASE Page

c. ASE page

(1) The ASE page provides control of the RFI and displays RFI detected threats/emitters.

(2) The system provides RFI threat/emitter information on the ASE and TSD pages.

(a) Detected threat type is indicated through the use of alphanumeric and other types of symbols.

(b) RFI detected threats/emitters are portrayed in one of two colors based upon their friendly/hostile status.

1) Friendly emitters are displayed in cyan.

2) Hostile and unknown (gray) emitters are displayed in yellow.

(c) When an RFI threat/emitter disappears from the threat environment, the corresponding symbol will continue to be displayed for up to 90 seconds.

1) The symbol will remain unchanged for the first 30 seconds.

2) The symbol will be displayed as ghosted partial intensity cyan (friendly) or partial intensity yellow (hostile/gray) for the remaining 60 seconds

3) After 90 seconds, the symbol will be removed from the display.

(d) The detected threat mode is indicated by a modified symbol to depict the threat modes of search; acquisition, track, and lock-on/launch for RFI detected threats/emitters.

(e) The direction to the threat is displayed in relation to the ownship.

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(3) Symbols representing detected RFI threats/emitters appear on the outside perimeter of the ASE footprint inside the map area edge.

(a) A maximum of ten top prioritized RFI threat symbols can be displayed.

1) A yellow homeplate symbol is displayed around the number one prioritized threat/emitter.

2) The homeplate symbol can be displayed as broken (dashed) or solid, depending upon the current threat mode of the #1 RFI emitter.

3) The homeplate symbol is broken only when the #1 RFI emitter is a search radar or a tracking radar operating in search mode.

(b) Threat mode for RFI threat/emitter symbols is the same as RLWR pulse radar threats.

(c) The RFI threats can be displayed in any one of four possible threat modes.

(d) It is important to note that not all radar threats have all four threat modes associated with them.

(e) The threat mode symbology is presented in yellow and is delineated as follows:

1) Search - symbol only

2) Acquisition - symbol with a box

3) Track - symbol with a box and a dashed line to the ownship

4) Lock-On/Launch - symbol with a box and a dashed line to the ownship with the box flashing at a 4 Hz rate

(f) The display of symbols representing ground-based RFI detected threats/emitters is modified to indicate coarse/fine DF accuracy.

1) An RFI threat/emitter that has been detected in the fine DF area is displayed with a triangle at the bottom center of the symbol.

2) Threats/emitters detected in the coarse DF area are displayed without the triangle.

(4) Threat symbol display priority is based on lethality assessment and time of occurrence of the incoming threat data into the DPs (i.e., the first threat symbol data has highest priority, the last threat symbol data has lowest priority).

(5) When any of the first three threat symbol azimuths are within 15º of each other, de-clumping rules will be applied:

(a) The number one threat symbol will not be displaced from its original azimuth.

(b) Threat symbol numbers two and three may be displaced in order to maintain at least 15° separation from each other and from threat symbol number one.

(c) All other threat symbols will be displayed on their original azimuths.


(a) RFI enable On/Off button

1) Used to enable/disable power to the RFI system.

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2) This button legend is only displayed if the MMA status (PINNED/NORM) is pinned, or the MMA is installed and the FCR is powered on.

(b) RFI emitter status window

1) Displays the current number of RFI threats/emitters being displayed on the ASE page.

2) The TSD and FCR pages may not show all RFI threats/emitters when they are merged with FCR targets.

3) This status window is removed from the display if no RFI threats/emitters are currently being displayed.

(c) Cursor Acquisition (CAQ) Button

1) This maintained option button permits the enabling and disabling of the RFI cursor acquisition function.

2) This function is used to rapidly select RFI detected threats as the acquisition source when the selected sight is Target Acquisition and Designation System (TADS) or Helmet Mounted Display (HMD).

3) To initiate the cursor acquisition of an RFI threat, the CAQ button is selected which will enable the CAQ function and pseudo freeze the RFI threat/emitter symbols for easier cursor acquisition.

4) Selecting the desired RFI threat using the display cursor will cause the acquisition source to automatically transition to RFI, if it is not already, and assign that point as the acquisition source for the selected sight.

5) If the RFI threat symbol selected is not the current number one emitter, a second yellow homeplate symbol with a partial intensity yellow fill (shaded) will be placed around the selected RFI threat symbol.

6) If the slave switch is actioned and TADS is the selected sight, the TADS will slave to the line of sight of the RFI threat just selected.

7) If HMD is the selected sight, cueing dots are provided to the crewmember on the HDU.

8) With HMD as the selected sight in the pilot crewstation, cueing for the HMD is automatically enabled when the RFI threat symbol is selected.

9) Since each crewmember can have a different sight, each crewmember can have a different RFI threat selected.

10) The RFI detected threat/emitter symbols will not be selectable on the ASE or TSD pages when the FCR is the selected sight.

11) Sight cueing symbology will indicate when a selected RFI threat is outside the gimbal limits of the TADS or HMD.

12) The CAQ function is also available on the TSD page.

13) The CAQ label will be barriered if the RFI is off.

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d. ASE UTIL page

(1) The ASE UTIL page contains numerous functions that are used to configure the ASE subsystem.

(2) ASE UTIL page functions

(a) RFI TRAIN button

1) This maintained option button is used to activate the RFI system training mode.

2) While in the training mode, the RFI system will provide an onboard simulation of RFI detected emitters for crew training purposes.

3) This set of emitters is a contrived (canned) set of threats that always appear at the same geographic location on the appropriate MPD pages, regardless of the heading of the aircraft or the position of the FCR centerline.

4) A total of 10 emitters are provided for processing and display, of which nine are hostile and one is friendly.

5) The FCR PSP and the DPs process these simulated emitters as though they are real time detected emitters.

6) The selection of the HOSTILE emitter display state declutters the friendly emitters from the display.

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7) The possibility of correlation between a real time FCR target and a simulated RFI emitter does exist, provided their azimuths are coincident and all other merge criteria is met.

8) This selection is also available on the FCR UTIL page.

9) It is displayed only when the MMA is installed and the RFI is powered on.

10) The selection is displayed with a non-selectable barrier if the MMA status is pinned.

11) Selection of the RFI training mode will precipitate the display of an “RFI FAULT” advisory on the UFD and MPD, and an “RFI FAIL” fault message.

12) These messages will appear 10 sec. after the selection is made and are the result of MUX bus update rate incompatibility between the RFI processor and the FCR PSP while the RFI system is in the training mode.

(b) RFI MODE button

1) A two-state option button used to select the emitter display state of the RFI system.

2) The two available options are ALL and HOSTILE. The current selection is common to both crewstations.

a) With ALL selected, all RFI detected emitters, to include hostile, friendly and unknown emitters, are available for display.

b) With HOSTILE selected, the system will discriminate and only display those RFI detected emitters that are determined to be hostile.

3) This selection is also available on the FCR UTIL page and is displayed only when the MMA is installed and the RFI is powered on.

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Figure 74. TSD Page

e. TSD page

(1) The TSD page displays both RLWR and RFI threat/emitter symbols in much the same manner as on the ASE page.

(2) These symbols are displayed on both the navigation and attack phases of the TSD provided if the RFI and RLWR threat options are selected for display on the appropriate TSD SHOW page.

(3) These display options can be manually selected by the operator in each crewstation, or can be automatically selected by the system as part of the ASE Autopage function for each crewstation.

(4) On the TSD page, the ASE footprint is displayed only if threats are selected for presentation and at least one threat exists for display.

(5) The TSD ASE footprint is a box that is displayed just inside the TSD map boundary box.

(6) Symbols representing RLWR threats are displayed on the inside of the footprint. RFI detected threat/emitter symbols are displayed on the outside of the footprint.

(7) RLWR threat symbols appear at the inside perimeter of the TSD ASE footprint.

(a) The only exception is the uncorrelated C/D band threat symbol, which always appears directly in front of the ownship symbol on the display.

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(b) RFI threat/emitter symbols appear at the outside perimeter, between the footprint and the TSD map boundary box.

(8) Access to the ASE page is provided on the TSD page via the ASE bezel button.

(9) CAQ function is also available on the TSD page and is selectable via the bezel button.

(a) This CAQ button is a maintained option button that permits the enabling and disabling of the RFI cursor acquisition function.

(b) It provides the same capability as the ASE page.

Figure 75. FCR Page

f. FCR page

(1) The FCR page displays up to 10 highest priority RFI threat/emitter symbols at the outside perimeter of the FCR footprint.

(2) These symbols are displayed to provide increased situational awareness and to precipitate the cued search function and the correlation of RFI threats/emitters with FCR targets.

(3) RLWR threat symbols are not displayed on the FCR page.

(4) The display of RFI threat/emitter symbols is similar to that of the ASE and TSD pages with a few exceptions.

(5) There is no ownship symbol displayed on the FCR page.

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(6) Two tick marks are provided on the outside of the FCR footprint, at approximately the three and nine o’clock positions. The tick marks depict the 90° positions of the current FCR scan.

(7) The RFI threat/emitter symbols are displayed along the peripheral border of the Wide Field-Of-View (WFOV) scan sector symbology regardless of the currently selected FOV.

(8) These symbols are normally displayed with reference to the currently displayed FCR scan.

(9) Initially, the RFI threat symbol position is dynamically updated on the FCR page to depict relative bearing referenced to aircraft heading.

(10) Once an FCR scan is invoked and at least one target is detected, RFI threat symbols are statically displayed (frozen).

(11) This is true regardless of the FCR detected target(s) relationship to the RFI detected threats.

(12) Freezing of RFI threat symbology provides a snapshot of the relationship between FCR targets that were detected during the current scan, and currently or recently detected RFI threats.

(13) The display of RFI threat symbol position is not dynamically updated during an FCR scan.

(14) The display of RFI threat symbol position remains static, referenced to the currently displayed FCR scan, until the FCR targets have been cleared via one of the following methods:

(a) Cycle power to the FCR system

(b) Change FCR mode

1) If the FCR mode is Ground Targeting Mode (GTM) or Radar Map (RMAP), selecting Air Targeting Mode (ATM) or Terrain Profile Mode (TPM) mode will clear FCR targets from the display.

2) If the FCR mode is ATM, selecting GTM, RMAP, or TPM mode will clear the FCR targets from the display.

(c) Perform an FCR scan or cued search in which no targets are detected.

(15) RFI threats/emitters can be correlated with FCR targets

(a) When they are merged by the system, the RFI threat/emitter symbols are removed from the display and replaced with a corresponding FCR target symbol appearing inside the FCR footprint.

(b) RFI threats/emitters can also be unmerged by the system and their symbols placed back outside the FCR footprint.

(16) Cued search function

(a) The RFI cued search is an FCR sight function which positions the centerline of the FCR antenna on any one of the detected RFI threats, for an FCR scan.

(b) A cued search of an RFI threat can only be performed in the crewstation in which FCR is the selected sight. A cued search may be initiated in two ways.

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(c) The first way a cued search can be initiated is by pressing the CUED button on the left ORT handgrip or on the mission portion of either collective grip.

1) Based on the characteristics of the RFI emitter this selection causes the following actions to occur

a) The centerline of the FCR antenna is slewed to the RFI number one emitter.

b) The FCR mode is automatically selected based on the RFI emitter type.

c) If the selected emitter is an airborne type, the FCR mode is commanded to ATM.

d) If the selected emitter type is a ground type, the FCR mode is commanded to RMAP with RMAP video displayed. This holds true unless the FCR is already in a GTM mode.

e) If the FCR is already in GTM mode, the FCR remains in that mode.

f) If the FCR is already in RMAP mode, the FCR remains in that mode, with the selected RMAP video status (On/Off) unchanged.

g) This allows the operator to have the GTM or RMAP display in his preferred format.

h) If the selected emitter type is an unknown type, or can be either an airborne or ground type, the FCR mode is commanded to RMAP with RMAP video displayed.

2) The FCR scan size (FOV) is automatically selected based on the selected FCR mode and the DF accuracy of the selected RFI emitter.

a) If the FCR mode is ATM, the FCR FOV is commanded to narrow, regardless of the DF accuracy of the RFI emitter.

b) If the FCR mode is GTM or RMAP, the commanded FCR FOV is dependent upon the DF accuracy of the RFI emitter.

1 If the DF accuracy of the RFI emitter is coarse, the FCR FOV is commanded to wide.

2 If the DF accuracy of the RFI emitter is fine, the FCR FOV is commanded to zoom.

3) The slave and link functions are disengaged (if appropriate) in the crewstation in which FCR is the selected sight.

4) The FCR is automatically commanded to perform a single scan in the selected FOV about the RFI emitter azimuth.

5) Continual actioning of the CUED button will repeat this process for each RFI threat in the RFI cued list, in priority order.

(d) The second way is to select an RFI threat symbol on the FCR page using the cursor.

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1) This will slew the centerline of the FCR antenna to the RFI threat, but the FCR will not automatically initiate a scan.

2) If a scan is desired, the operator must manually initiate a scan via the FCR scan switch located on the left ORT handgrip (CPG only) or the mission portion of either collective grip.

3) Once a cued search is performed on an RFI threat, that particular threat is tagged in the RFI cued search list.

4) Emitters tagged in the RFI cued list will not be selectable for another cued search unless the RFI cued list tags are cleared from the list.

5) The following actions clear the RFI cued list tags, permitting a cued search via the CUED button on those RFI emitters once again.

a) The link mode is selected.

b) The entire RFI cued list has had a cued search performed on it.

c) The FCR scan size (FOV) is changed.

d) A new #1 RFI emitter is listed.

e) The FCR mode is changed to TPM.

f) When the CPG has control of the FCR, the slave mode changes from not slaved to slaved.

6) The actioning of the CUED button, following a cursor acquisition and manually initiated scan of an RFI threat, precipitates a cued search of the highest priority RFI threat on which a cued search has not been performed.

(e) If the currently selected sight is not FCR, the cursor selection of an RFI threat symbol on the FCR page is ignored. Attempting to cue an RFI threat that is outside the gimbal limits of the FCR antenna, will cause the “LIMITS” message to be displayed in the high action display.

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Figure 76. FCR UTIL Page

g. FCR UTIL page

(1) The FCR UTIL page provides another means of enabling/disabling the RFI system via the RFI Enable On/Off Button. This button legend is only displayed when the RFI is installed in the aircraft.

(2) The RFI training mode and the RFI emitter display mode selections are also accessible from the FCR UTIL page.

(3) The RFI TRAIN maintained option button and the RFI MODE two-state option button supply access to these functions in addition to their availability on the ASE UTIL page.

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Figure 77. WPN UTIL Pages

h. WPN UTIL page

(1) The ASE page is accessible from the WPN UTIL page via the ASE bezel button in either crewstation.

(2) The RFI system can be enabled/disabled from the WPN UTIL page in either crewstation. This button legend is only displayed when the RFI is installed in the aircraft.

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Figure 78. ASE Advisories

i. Advisories

RFI FAULT

The RFI is operating in a degraded mode or a blade index failure has been detected.

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Figure 79. ASE and ASE UTIL Page

j. System initialization


If system power-up occurs while the aircraft is on the ground (squat switch indicates on ground and both throttles are in the Off/Stop position), the ASE subsystem selections are initialized to a default state or to the DTC values. The system default values areas follows:

(a) RFI On/Off mode = off

(b) RFI Train mode = off

(c) ASE autopage selections = search


If the power-up occurs while the aircraft is airborne, the RFI system selections are initialized to the values stored at power down.

(3) Subsystem shutdown

During the shutdown routine, the system saves the current value of the RFI system parameters in non-volatile memory

(a) RFI On/Off mode

(b) RFI train mode

(c) RFI emitter display mode

(d) RFI self-test mode

(e) ASE autopage selections

k. ASE degraded mode of operation

A dual EGI failure will cause RFI threats to no longer be updated relative to aircraft heading.

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Figure 80. DMS NAV/ASE and RFI IBIT Pages

l. AN/APR-48A RFI system BIT

The RFI system has an elaborate self-test scheme that includes PBIT, CBIT, and IBIT. The RFI BIT verifies the integrity of the RFI antenna assembly, RFI receiver, RFI processor, UDM, and system software. The RFI BIT function also calibrates the RFI receiver and initializes the system for operational use.

(1) PBIT

(a) PBIT is initiated by a power-on reset. PBIT verifies the hardware and software operation of the RFI processor and the initializes the RFI system for operational use.

(b) The PBIT provides a high confidence in the system integrity of the RFI processor by testing all operational functions.

(c) Following completion of all tests, the contents of the program Electronic Erasable Programmable Read Only Memory (EEPROM) and User Data Module UDM) EEPROM are transferred to the main memory (RAM).

(2) CBIT

(a) CBIT is executed on a periodic basis, under the control of the RFI executive function.

1) It is executed immediately after power on (following execution of PBIT) and periodically at 30 sec. intervals.

2) The duration of CBIT is limited to 1.6 sec. to minimize interference with the mission target acquisition requirements.

(b) All BIT functions that reside in main memory co-reside with the software OFP. To minimize the impact on the OFP size, a 12K block of memory has been allocated to all of the BIT functions.

(c) The CBIT routine is performed in the background and is transparent to the operator.

(d) The CBIT has no effect on the integrity of the OFP or its database, so that normal operational processing can be resumed immediately upon the completion of CBIT execution.

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(3) IBIT

(a) The RFI system IBIT is normally executed in conjunction with the FCR IBIT unless the RFI system is employed in the stand-alone configuration.

1) The RFI IBIT can also be performed via the NAV/ASE IBIT page by selecting RFI bezel button.

2) The RFI IBIT button legend is removed from the NAV/ASE IBIT page if the RFI processor is not installed in the aircraft.

3) The RFI IBIT button is displayed with a non-selectable barrier if the system is turned off.

(b) Once an IBIT is initiated, the RFI IBIT page is presented with the IBIT listing area displayed in the center of the page.

(c) At the completion of the self-test, any faults detected are displayed in the IBIT listing area under the test status line.

(d) Any RFI MUX faults detected by the WPs during the IBIT are also displayed.

(e) Up to two pages of IBIT faults can be displayed if necessary.

(f) If no failures are detected during the self-test, the message “NO FAULTS FOUND” is displayed on the first line of the IBIT listing area.

(g) IBIT performs a comprehensive test of both the RFI processor and RFI receiver LRUs, including the interface between the two units.

(h) IBIT provides a high confidence in the operability of the RFI System by testing all operational functions.

(i) The RFI IBIT capability detects 95% of the critical faults for both hardware and software.

(4) The BIT is not an end-to-end test of the system. The only method of testing the system from end-to-end is by utilizing a radar threat signal simulator to illuminate the antennas with simulated threat signals and verify the visual indications present in the crewstations.

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m. AN/APR-48A RFI BIT status/associated faults

The DMS presents RFI related faults on the DMS page, DMS FAULT page, and/or RFI IBIT page if the failure has been detected during any BIT test.

(1) HPSM1 KD107 CONTACTOR FAIL (RFI PWR CNT)

The relay that supplies power to the RFI has failed a command status check, or there is no power to energize the relay.

(2) HPSM1 RFI CKT BRKR (RFI CB FAIL)

The HPSM1 has detected a KD107 circuit breaker fault.

(3) FCR LRU 3 RFI PROC FAIL (FCR FAIL)

This LRU has been identified as one of three possible replacement candidates.

(4) FCR MMA 4A6 RFI ANT (FCR FAIL)


(5) FCR MMA 4A7 RFI RCVR (FCR FAIL)


(6) RFI BLADE POSITION INDICATOR DEGRADED (RFI BPI DEGR)

(a) The RFI has detected that the blade position indication has failed. Target positions may be inaccurate.

(b) Confirm seeker acquisition before firing. IBIT (on the ground with blades turning) is required to identify this problem.

(7) RFI FAIL (RFI FAIL)

The RFI is non-operational.

(8) RFI DEGRADED (RFI DEGRADED)

The RFI has a partial failure and is operating in a degraded fashion, but is still operational.

(9) RFI CHANNEL 3 BUS A NO RESPONSE (RFI FAULT):

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This fault indicates the RFI is not responding to WP Bus controller commands on MUX bus channel 3A.

(10) RFI CHANNEL 3 BUS B NO RESPONSE (RFI FAULT)

This fault indicates the RFI is not responding to WP Bus controller commands on MUX bus channel 3B.

(11) RFI FAIL (RFI FAIL)

This fault indicates the RFI is not responding to WP Bus controller commands on either MUX bus channel 3A or channel 3B.

Check On Learning

1. What is the degree of coverage for coarse DF operation?

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2. Which component contains the classified portion of the RFI operational software?

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3. Where are RFI threat symbols displayed on the ASE page?

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4. How many prioritized RFI threats can be displayed on the ASE page?

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5. Does the RFI have an IBIT capability? If available, which page would you use?

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united states army aviation center fort rucker, alabama

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