summitek pim measurement procedure v1.1

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©2010 Summitek Instruments, Inc. All rights reserved.

Passive Intermodulation (PIM) Measurement Procedure V1.1

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1. Passive InterModulation (PIM) Overview

Passive Intermodulation (PIM) occurs in passive devices whenever two or more RF signals encounter non-linear electrical junctions or materials. The interference generated is mathematically related to the localized downlink frequencies and can result in a noise rise in the uplink band of one or more systems sharing the RF infrastructure. The impact of PIM on the network performance can be severe, especially for wideband systems such as CDMA, UMTS or LTE. PIM interference can lead to desensitization of the receiver causing increased dropped calls, increased access failures, pre-mature hand-offs, decreased data transmission rates and decreased system coverage and capacity.

Any component in the RF path can be the source of the PIM interference including antennas, TMAs, diplexers, duplexers, surge arrestors, cables and connectors. In addition, loose mechanical connections or rusty surfaces external to the antenna system can generate PIM when subjected to high radiated RF power.

1.1 PIM Sources

PIM can be generated in any component that contains non-linear materials or junctions in the RF path. Ferromagnetic materials are the most common materials to avoid and include ferrite, nickel, (including nickel plating) and steels (including some stainless steels.) These materials exhibit hysteresis when exposed to reversing magnetic fields resulting in PIM generation.

PIM can also be generated in components with manufacturing workmanship defects such as cold or cracked solder joints or poorly made mechanical contacts. If these defects are exposed to high RF currents PIM can be generated. RF equipment manufactures perform factory PIM tests on components to eliminate PIM caused by design and manufacturing defects.

In the field, PIM can be caused by components that were damaged in transit to the cell site, installation workmanship issues and by external PIM sources. Some of these include:

• Contaminated surfaces or contacts due to dirt, dust, moisture or oxidation

• Loose mechanical junctions due to inadequate torque, poor alignment or poorly prepared contact surfaces.

• Loose mechanical junctions caused transportation shock or vibration. (Can be due to rough handling or insufficient product packaging.)

• Metal flakes or shavings inside RF connections

• Inconsistent metal-to-metal contact between RF connector surfaces caused by any of the following:

o Trapped dielectric materials (adhesives, foam, etc.)

o Cracks or distortions at the end of the outer conductor of coaxial cables, often caused by over tightening the back nut during installation.

o Solid inner conductors distorted in the preparation process causing these to be out of round or tapered over the mating length.

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o Hollow inner conductors excessively enlarged or made oval during the preparation process.

• Dissimilar metals in direct contact

• Nearby metallic objects in the direct beam and side lobes of the transmit antenna including rusty bolts, roof flashing, vent pipes, guy wires, etc.

Over time, RF interconnections and components at the cell site are exposed to mechanical stress due to thermal cycling and wind forces. Junctions that were originally good can become PIM generators over time due to the formation of stress cracks or by physical loosening.

1.2 PIM Order

The PIM signals generated in a system are mathematical combinations of the downlink frequencies present in that system. In the simple two-tone case shown below, f1 and f2 represent two downlink frequencies present at the cell site and ± m·f1 ± n·f2 represent the PIM signals generated by those downlink frequencies.

The PIM signals are identified as 3rd order (IM3), 5th order (IM5), 7th order (IM7), etc. where the order number equals the sum of the frequency multipliers, or m + n.

IM3 = 2f1 ± 1f2, (2+1=3)

IM4 = 2f1 ± 2f2, (2+2=4)

IM5 = 3f1 ± 2f2, (3+2=5), etc

In general, the lower the PIM order number, the higher the magnitude of the PIM signal. In addition, odd products typically fall closer to the two downlink frequencies and are more likely to cause interference in that system’s receive band.

RX Band TX Band

Example: f1 = 869 MHz, f1 = 894 MHz

IM3 = 2x 869 MHz - 1x 894 MHz = 844 MHz

IM3 = 2x 894 MHz - 1x 869 MHz = 919 MHz

IM5 = 3x 869 MHz - 2x 894 MHz = 819 MHz

IM5 = 3x 894 MHz - 2x 869 MHz = 944 MHz

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1.3 PIM Test Equipment

PIM test equipment transmits two high power signals into the line or device under test. If the test signals encounter a non-linear junction mixing occurs causing the Intermodulation frequencies to be generated. The test signals continue through the system and are either absorbed by a load or broadcast out the antenna. The Intermodulation signals travel in all directions from the point of generation. In a coaxial system this means they travel toward the load or antenna as well as back in the direction of the PIM test equipment.

The Intermodulation signals that fall within the Rx band of the system under test are directed toward the receiver through a duplexer. These low level signals are filtered and amplified before being applied to the PIM test set receiver.

This type of measurement is known as a reverse (or reflected) PIM measurement. Accurate PIM measurement is a challenge given that extremely low level signals need to be measured in the presence of relatively high power RF signals. IEC 62037, the international standard for PIM testing, specifies more details regarding PIM measurement.

When a load is used to absorb the transmit signals from the test equipment it is critical that the load be a “LOW PIM” load. If the load contains defects that produce high levels of PIM, the test equipment will not distinguish PIM from the load vs. PIM from the system under test. A failing PIM measurement will result.

It is also important to note that the load used for VSWR sweep testing should not be used during PIM testing. These precision loads are not designed to handle the power levels generated by a PIM test set and will be destroyed instantly.

It is also important that the PIM generated within the test equipment (residual PIM) be well below the site certification PIM level. Residual PIM of the test set-up (PIM tester, loads, test leads, adapters) should be verified before each use to make sure no damage has occurred since the previous use.

PIM Source

PIM PIM

TX 1

TX 2

TX 1 TX 1

TX 2 TX 2

PIM Test Equipment

Low PIM Load

PIM

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1.4 PIM Measurement Units

PIM is specified in dBm or dBc.

• dBm is an absolute power measurement and reports the magnitude of the PIM signal in decibels relative to 1 mW.

• dBc is a relative power measurement and reports the magnitude of the PIM signal in decibels relative to the carrier or test tone power level.

The absolute value of the PIM signal is the same regardless of whether it is described in dBm or dBc. The only difference is the reference chosen to describe the PIM signal. The difference between dBm and dBc is a constant and will be 43 dB for 20W test sets or 33 dB for 2W test sets.

Example 1: A -100 dBm PIM signal caused by two +43 dBm (20W) tones can also be specified as a -143 dBc PIM level (-100 dBm – 43 dB = -143 dBc).

Example 2: A -110 dBm PIM signal caused by two +33 dBm (2W) tones can also be specified as a -143 dBc PIM level (-110 dBm – 33 dB = -143 dBc).

Carrier power level must always be specified with the given PIM performance level. In the above example the dBc level is the same but the level of quality indicated is very different due to the difference in carrier power.

0 dBm

+43 dBm

-100 dBm

0 dBc

-143 dBc

Tx1

PIM PIM

dBm dBc

Tx2 Tx1 Tx2

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1.5 PIM Measurement Power

The magnitude of the PIM signal generated by a given defect is highly dependent on the power level of the two RF signals interacting with that defect. A 3rd Order PIM product, for example, will change between 2.2 and 3.0 dB in magnitude for every 1 dB change in carrier power. An average level of 2.5 dB / dB can be used for approximation.

Example: A component produces an IM3 level of -97 dBm when measured using two +43 dBm (20W) tones. What would the expected IM3 level be if the test power were reduced to +33 dBm (2W)?

Change in power = 43 dBm to 33 dBm = -10 dB

Change in IM3 = 2.5x -10dB = -25 dB.

97dBm (@2x 20W) – 25dB = -122 dBm (@2x 2W)

The relationship above is accurate for loose metal to metal contacts, dissimilar metal junctions and other typical defects that behave like a diode. Ferrite devices will exhibit a different PIM slope vs. carrier power.

The above example again illustrates that carrier power level must always be specified with the given PIM performance level. IEC 62037 specifies +43 dBm (20W) as the industry standard test power for PIM testing. This power level has been used by RF equipment manufactures for more than a decade to establish PASS / FAIL specifications for RF components.

Low power (2W), battery operated test sets are available for testing in locations where AC power is not available or where transporting a 20W test set is not feasible. These 2W systems are useful for finding gross PIM failures in components and are useful for troubleshooting sites to determine the location of PIM problems. Results may vary, however, when comparing results to 20W tests on the same device due to RF heating effects and the presence of defects that exhibit non-linear PIM slope vs. test power.

1.6 PIM Measurement Frequency

Typical PIM sources found in the field are broadband, meaning they will produce approximately the same magnitude of PIM when tested using an 850 MHz test set as they will when tested using 1900 MHz test set. Which test frequencies to use to test a particular RF path are determined by the following:

1. All components in the path (Cables, Antennas, TMA’s, etc.) must be able to pass the two test frequencies, f1 and f2, and be able to pass the IM frequency you are measuring.

2. The two test frequencies must be within the Service Provider’s licensed spectrum or be guard band frequencies between licensed spectrum blocks. This applies to all system level tests where the test frequencies will be broadcast through the antenna.

3. The two test frequencies need to be selected so that they will produce the specified IM product within the receive band for that system. When IM3 is specified this will typically require test tones with wider frequency spacing than can be achieved within the licensed

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frequency block for a given market. For this reason, guard band frequencies will typically be selected.

PIM test equipment is a tool used to find and correct workmanship issues and faulty components at the cell site. The specific test frequencies used to identify these defects are not critical as long as the above criteria are met.

1.7 PIM Measurement Mode

1.7.1 Swept frequency Mode

PIM test equipment measures the vector sum of all PIM sources present on an RF path. If two PIM sources of approximately equal magnitude are present on the RF path and are physically separated in such a way that the two signals arrive at the PIM test equipment exactly 180º out of phase, the two PIM signals will cancel, indicating “no PIM is present” in the system. Changing the test frequencies, f1 or f2, will change the generated PIM frequency and the phase relationship between multiple PIM signals on the line, if they exist. “Sweeping” across multiple test frequency combinations provides a range of PIM data points to ensure that a “BAD” site is not reported as a “GOOD” site due to an unfortunate selection of test frequencies.

WARNING: Swept frequency mode will transmit frequencies outside of the Service Provider’s licensed spectrum. This mode should only be used to test systems terminated into a low PIM load.

In Swept Frequency mode the test equipment automatically changes the two test frequencies and displays the resulting IM frequency

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1.7.2 Fixed frequency Mode

In fixed frequency mode the two test frequencies, f1 and f2, remain fixed during the duration of the test. The instantaneous PIM value will be displayed by the test equipment. Certain equipment has the ability to display and record PIM vs. time to provide a “picture” of the PIM stability during the duration of the test. Fixed frequency mode is required for system level tests that broadcast the test signals through the antenna. If there is a concern that the system is providing a false reading due PIM signal phasing, manually select alternate fixed frequencies (guard band or the Service Provider’s licensed frequencies) to provide points of comparison.

In Fixed Frequency mode the two test frequencies do not change through the duration of the test.

Time trace mode displays the PIM value vs. time. In this case a loose RF connector is found by tapping on the connection

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2. PIM Measurement Guidelines

2.1 RF Safety

PIM test equipment is capable of producing up to 50W of RF power in the 700 to 2100 MHz region. Users must take proper precautions to minimize exposure to these RF fields:

• Always terminate the output port of the test equipment into a load, a loaded line or a line that will radiate the energy to free space before turning on the RF power.

• Always turn off the RF power whenever a test is not being conducted.

• Always turn off the RF power before disconnecting a RF connection on a line under test. Burns to fingers and permanent damage to eyes can result from exposure to connectors carrying high levels of RF power.

• Ensure that any antenna being tested is placed so that no personnel are exposed to RF field levels in excess of the maximum allowable exposure limits.

2.2 RF Connector care

The RF connectors used during testing must be cleaned and handled properly to ensure low PIM results. This includes the RF connectors on test adapters, test cables, test loads and the test equipment itself.

• Clean the RF connectors regularly.

• Care should be taken to ensure the connectors are aligned when interfacing.

• Be sure that the connector is fully seated before tightening the coupling nut. Tighten the locking nut by hand initially, and then only do a final torque using a wrench.

• Remove o-rings from all test equipment adapters and test leads. This will reduce the torque required to achieve a tight, low PIM connection during test and extend the life of the connectors. (Do not remove o-rings from the site jumper cables.)

• If a torque wrench is used, torque the 7-16 connector to a maximum of 25 N-m.

• Do not allow the body of the connector to rotate while tightening.

• Keep protective caps installed on RF connectors whenever they are not in use.

RF connectors have a finite life and are typically rated for 500 mate / de-mate cycles by connector manufacturers. Longer life is achievable with proper care.

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2.3 Equipment Verification Procedure

Verify that the equipment calibration is current before testing. PIM test equipment should be returned to Summitek each year for annual calibration and maintenance check.

Before testing each day it is important to verify that the PIM test equipment is working properly and that the test components (loads, adapters, cables) are in good condition. Contact Summitek technical support if alarms are present or if the equipment does not perform as indicated in the procedure below. Replace any damaged components found during inspection.

Step Materials Criteria iHA iMT iQA

Verify Alarm status

None During use the equipment will run diagnostic checks and report alarms if they exist. Verify that no alarms are indicated.

X X X

Visually inspect RF connectors on the PIM analyzer, loads, test leads and adapters.

None Verify connectors are free of contamination, metal flakes or physical damage to mating surfaces.

X X X

Clean RF connectors.

Isopropyl alcohol wipe with Q-tip Remove metal flakes and contamination from mating surfaces

X X X

Set / Verify RF output power to +43 dBm ±0.5 dB

Install either load on the RF output connector of the PIM analyzer.

iMT Series: Set Carrier 1 & 2 power to +43 dBm ±0.5 dB

iQA Series: Verify that the power level has been set to +43 dBm.

N/A Set Check

Verify PIM analyzer receiver calibration and HPA operation.

Install the High PIM load (PIM source) on RF output connector.

Expected IM levels:

700 / 850 MHz:

20 W: ≤ -75 dBm (-118dBc) ±3 dB

2 W: ≤ -102 dBm (-135dBc) ±4 dB

1900 / 2100 MHz:

20 W: ≤ -77 dBm (-120dBc) ± 3 dB

2 W: ≤ -104 dBm (-137 dBc) ±4 dB

X

X

X

Verify residual PIM of the Load + test lead + PIM analyzer.

Attach desired test lead to RF output connector. Attach low PIM load (adapters may be required) to other end of test lead.

Flex / tap RF connections to make sure the residual PIM does not exceed the following levels:

20 W: ≤ -107 dBm (-150 dBc)

2 W ≤ -130 dBm (-163 dBc)

X

X

X

High PIM Load (white)

Low PIM Load (black)

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2.4 Acceptance Criteria:

Configuration 3rd

Order IM with 2x 20W (+43 dBm) Test Power

3rd

Order IM with 2x 2W (+33 dBm) Test Power

New Construction -140 dBc (-97 dBm) Max. -155 dBc (-122 dBm) Max.

Legacy Site Modifications -130 dBc (-87 dBm) Max. -145 dBc (-112 dBm) Max.

• 20W (+43 dBm) test power is required for certification testing.

• 2W (+33 dBm) test sets are useful for troubleshooting but should not be used for site certification. The pass/fail criteria above should be used when testing components using a 2W test set.

• From a performance perspective it would be desirable for all sites (new and legacy) to achieve new equipment performance levels. It is recognized, however, that this will be more difficult to achieve on older sites due to component aging. The reduced levels shown are a compromise between desired performance and time / effort to achieve this performance.

2.4.1 Peak vs. Instantaneous PIM

The above acceptance criteria apply to the PEAK, or maximum PIM value recorded during the duration of the test.

2.4.2 Dynamic vs. Static PIM

The above acceptance criteria apply when the components and interconnections on the line are subjected to light mechanical stress or “dynamic” test conditions. The “tap test” is the preferred method for subjecting components and interconnections to dynamic stresses. If the component or RF connector has loose internal connections or internal debris that can result in increased PIM (as identified during dynamic testing) there is a high probability that the condition will present itself in the future and invariably at the most inconvenient time.

Tap test guidelines:

• Tap RF components such as TMA’s, Filters and Antennas using a hard plastic or rubberized metal object to prevent nicking or damaging protective finishes.

• Lightly tap the nut and/or back shell of RF connectors using a hard plastic or metal object. Do not tap the coaxial cable itself as this could cause dents in the line.

Tap with sufficient force to excite PIM problems if they exist but do not tap with excessive force. A good rule of thumb is that if you tapped your unprotected palm with the same force, it should not hurt.

Tap before weatherproofing is installed on RF interconnections. If weatherproofing is in place, substitute a “flex test” to apply stress to the interconnection.

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Flex test guidelines:

• For stiff cables, rock the RF connector back & forth in two orthogonal directions while holding the cable rigid.

• For flexible cables, hold the RF connector rigid and flex the cable back & forth in two orthogonal directions. Hold the cable approximately 12 inches away from the connector and flex the cable ±4 inches in each direction.

Metal end for tapping RF Connectors

Rubberized end for tapping TMA’s, Filters, Antennas. Example

Tapping Tool:

PIM rises above the Pass / Fail limit while being tapped but passes when static. This is a failing result and the defective component should be repaired or replaced.

TAPPING TAPPING

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2.4.3 External PIM Sources

In some cases acceptable PIM results will not be achievable due to external PIM sources at the site. This is likely to occur on roof-top sites where aesthetic requirements force the antennas to be located away from the building edge or on crowded sites where another company’s infrastructure may fall within the field of view of the antenna. In these cases PIM producing metal objects may be unavoidable in the field of view of the antenna and generate high levels of PIM.

It is not typically within the scope of work for an installation company to correct these external faults. It is expected, however, that the installation company will provide sufficient data to reasonably ensure that the fault is external. The following procedure will be used in this case:

Perform system PIM

test

NO

Disconnect jumper from the antenna port and attach a

low PIM load to the end of the line

Record Passing System

PIM

YES

NO

Correct PIM problems on the line and re-attach

jumper to the antenna port

Record Passing Loaded

Line PIM

YES

Measure antenna only on

ground or rooftop facing

skyward

NO

YES

Replace Antenna and re-attach

jumper to antenna port

Record Failing System

PIM

Record PassingAntenna

PIM

1

2 3

Submit reports 1, 2 & 3 demonstrating that the

PIM is external.

Submit comments or photographs if there are suspected sources for

the external PIM

Service Provider will monitor site performance and correct the external

PIM problem if economically justified.

FAIL PIM Test?

FAIL PIM Test?

FAIL PIM Test?

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2.5 PIM Test Reports

The Summitek iMT and iQA Series 20W test sets have the capability to produce test reports. The iQA Series generates these reports using the integrated panel PC and the iMT Series requires an external PC running iMT Interface Software. The iHA Series 2W test sets do not have reporting capability.

Reports should be submitted in PDF format and include the following information:

2.5.1 Report Header

• Site = Site Number per the Service Provider convention

• Sector = All

• Feeder = All

• Operator / Company = Company responsible for the test results.

2.5.2 Test Point Descriptions

• Test Point: Operators should record system level PIM results for each feed line at the site. Cable color codes may be entered as “Test Point Labels” to identify each line.

• Additional descriptive words may be added as needed to describe the test condition if other than a system level measurement.

It is good practice to include the PIM Load and PIM Source data measured during equipment verification on the site report.

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2.6 PIM Measurement Guidelines

2.6.1 System PIM Measurement

The figure to the right shows the RF plumbing at a typical cell site. Additional components such as TMA’s, Diplexers and Bias-T’s may be in place but will not impact the test process as long as these components are capable of passing both Tx test frequencies as well as the IM product being measured.

If narrow bandwidth components are installed in the system that block one or both Tx test frequencies or block the IM product frequency, these components must be by-passed during test.

Before performing a PIM test make sure there are no components installed on the line that would be damaged by +46 dBm composite Tx power. This may be the case on lines used for Rx only or in DAS installations.

A system level PIM test is conducted by disconnecting the RF connection at the BTS and attaching the test lead from the PIM test to the BTS jumper. (Point 1)

PIM testing is an iterative process. The flow chart shown in section 2.6.2 provides a logical process for isolating and correcting PIM problems at a cell site.

Use the tap test or flex test to identify loose mechanical connections. If the PIM problem can not be found using dynamic testing, move the Low PIM load to RF connection points closer to the test point. When a passing result is achieved the last component bypassed will be the faulty component.

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2.6.2 PIM Determination Flowchart

Connect PIM test set at Point 1 and perform

system PIM test

NO

Disconnect jumper from the antenna port and attach a low PIM load at Point 3. Repeat system PIM test.

Record Passing System

PIM

YES

NO

Re-attach feed line to surge

protector.

YES

Measure antenna only on

ground or rooftop facing

skyward

NO

YES

Re-attach top jumper to

antenna port

PIM source is external to the

system. Refer to section 2.4.3

FAIL PIM Test?

FAIL PIM Test?

FAIL PIM Test?

Connect PIM test set at Point 2 and perform feed system PIM test.

NO

YES

PIM problem exists between the BTS

and the feed cable. .

FAIL PIM Test?

Connect PIM test set at Point 1 and connect Low PIM load at Point 2. Use

PIM test equipment to identify and correct the PIM problem.

Replace Antenna

PIM problem exists between the surge protector and the

antenna.

Use PIM test equipment to identify and correct the

PIM problem.

Perform equipment verification in accordance

with section 2.3

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2.6.3 Systems with Remote Radio Heads (RRH):

PIM is only a concern in RF paths and is not a concern for fiber optic pathes. When a Remote Radio Head (RRH) is installed at a site, the system test points are at the jumper cables coming out of the RRH. It may be more convenient to test the antenna + jumper cables on the ground before hanging the antenna.

RRH

DC Fiber

+45 -45

ANT

PIM Test Points

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2.7 Component Level Testing

Field PIM test equipment is not intended to be used to validate component manufacturer’s PIM specifications. More sensitive test equipment in a controlled test environment is required for specification verification. Portable PIM test equipment can, however, be used to identify components that do not meet the site level PIM criteria identified in Section 3.4. Proper test techniques and test environments are necessary to ensure the validity of component level testing.

2.7.1 Antenna PIM Measurement

During PIM testing high power RF energy will be radiated from the antenna. Care must be taken to ensure that people near the test are not exposed to RF field levels in excess of the maximum allowable exposure limits and that the test environment must be free of PIM sources that could invalidate the results. The following guidelines should be followed:

• Do not PIM test antennas indoors. (Unless an anechoic chamber is available designed to absorb the RF energy.)

• Place the antenna on non-metallic supports at least 1 foot off the ground with the front of the antenna pointing to the sky.

• Position the test equipment to the top or bottom of the antenna (not to the sides.) Typical sector antennas have minimum radiation along the vertical axis.

• Position the antenna so that no metallic objects obstruct the view of the sky within the antenna’s half-power beamwidths (both azimuth and elevation.)

Note: Omni directional antennas typically must be mounted at the top of a tower during PIM testing to prevent “seeing” metallic objects within the antenna beam.

• Stay away from the front and sides of the antenna during test.

• Make sure the correct band PIM test equipment is used for each antenna port tested. The test equipment Tx signals + IM signal must fall within the operating band of the antenna port under test.

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2.7.2 Multi-Port Device PIM Measurement

The Portable PIM test gear measures only reverse IM products and this must be taken into account when measuring multi-port devices. Also, multi-port devices are often frequency selective and do not pass all cellular frequency bands through all ports. The correct frequency band PIM test equipment must be selected for the device tested. Devices at a site that do not pass both the Tx and IM frequencies of the PIM test equipment must be by-passed during a system level PIM test.

2.7.2.1 Cable Assemblies (2-port) :

Connect the test lead to one end of the cable under test and connect a low PIM load to the other end. This will minimize wear and tear on the test set output connector when testing a large number of cable assemblies.

2.7.2.2 Splitter or Combiner (3 or more ports):

Splitters divide the RF power at the input between two or more output ports. Connect the test lead from the PIM test equipment to the input port. Connect low PIM loads to all output ports.

DUT Low PIM Load Test lead

Output

Output

Input

Low PIM Loads DUT

Test lead

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2.7.2.3 Diplexer or Cross-Band Combiner (3-port):

Cross-band combiners are frequency dividers that are used to combine multiple frequency bands onto a common feeder. Connect the test lead from the PIM test equipment to the input port of the device. Connect a low PIM load to the output port that matches the operating band for the PIM test equipment. No load is required on the output port for the other frequency band.

2.7.2.4 Duplexer or Same-Band Combiner (3-port)

Duplexers are frequency dividers that are used to separate the Tx and Rx frequencies within a single operating band. PIM generated inside the Duplexer will exit through the Rx port of the device. The portable PIM test set measures only reverse PIM thus a spectrum analyzer is required to measure forward PIM exiting the Rx port. Connect the test lead from the PIM test equipment to the Tx port of the device. Connect a low PIM load to the Antenna output port for operator safety. Connect the Spectrum Analyzer to the Rx output port.

WARNING: Do not connect the Spectrum Analyzer to the Antenna port!

Recommended Spectrum Analyzer settings: Center Frequency = PIM frequency, Span 10 kHz, Resolution Bandwidth 100 Hz.

Spectrum Analyzer

Low PIM Load

DUT

Test leads

Rx

Tx

ANT

Band 2

Band 1

Band 1+2

Low PIM Load

DUT

Test lead No Load Required

Band 1 PIM Test Set

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2.7.2.5 Tower Mounted Amplifiers (TMA):

TMA’s pass the Tx signals from a BTS in the forward direction and amplify Rx signals from the mobiles in the reverse direction. The configuration of the TMA (duplexing or dual-duplexing) will determine how the TMA should be tested. The TMA can be either powered or not powered during test. If powered, PIM generated at or beyond the TMA will be amplified by the gain of the TMA.

2.7.2.5.1 Duplexing Tower Mounted Amplifier (DTMA):

Duplexing TMA’s (DTMA) have a common port that goes to the antenna and separate Tx and Rx ports going to the BTS. Do NOT transmit PIM test signals into the Rx port of a duplexing TMA as this will damage the LNA. DTMA’s require a Spectrum Analyzer in order to measure the transmitted IM signal. Connect the test lead from the PIM test equipment to the Tx port of the device. Connect a low PIM load to the antenna port for operator safety. Connect the Spectrum analyzer to the Rx port.

WARNING: Do not connect the Spectrum Analyzer to the ANT port!

Recommended Spectrum Analyzer settings: Center Frequency = PIM frequency, Span 10 kHz, Resolution Bandwidth 100 Hz.

2.7.2.5.2 Dual-Duplexing Tower Mounted Amplifier (DDTMA):

Dual-Duplexing TMA’s (DDTMA) have one port that goes to the antenna and one port that goes to the BTS. Connect the test lead from the PIM test equipment to the BTS port of the DDTMA. Connect a low PIM load to the Antenna port. Note the state of the TMA (powered, bypass, unpowered) in the test point label.

Spectrum Analyzer.

Rx Tx ANT

Low PIM Load

DTMA

Test lead Test lead

ANT BTS Low PIM Load

DDTMA

Test lead

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Appendix A: iMT Series – 20W PIM Tester

Summitek Model No.

iMT-800

Band: 850 MHz

Transmit Frequencies

869.0 MHz, 891.5 MHz (fixed)

Receive Frequency

846.5 MHz

1. Specifications:

• Measurement method: Reverse (reflected) PIM, 3rd

order

• Power per Tone: 2x 20W (+43 dBm)

• Transmit Frequencies: See table

• Receive Frequency (PIM): See table

• Residual Intermodulation: <-107dBm/-150 dBc max (-115 dBm/-158dBc typ.)

• Noise Floor: <-120 dBm

• Measurement range: -60 to -107.5 dBm (-60 to -120 dBm with laptop interface)

• Report capability: Data collection / reports generated via laptop software

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2. User Interface:

1 AC input, 110-230 VAC, illuminated on/off switch and fuse

2 RF “ON” warning LED

3 RF output port, 7-16 DIN female

4 Internal Low PIM Load, 7-16 DIN female

5 Spectrum Analyzer port, Type-N female

6 Data I/O connector, D9 female, RS232 interface

7 Alarm status LEDs

8 Power supply status LEDs

9 Mode Select Switch

10 Measurement level LEDs

11 Measurement mode LEDs

12 Active carrier LEDs

13 Multi-function switch (Power Adjust, Audio on/off)

1

2

3

4

5

6

7 8

9

10 11

12 13

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3. Equipment Verification

� Ensure MODE SELECT switch is in the OFF position

� Switch unit AC on & allow the unit to warm up for 5 minutes before use.

� Verify that the POWER SUPPLY LED’s are all on and that the ALARMS LED’s are all off.

� Inspect and clean all RF connectors to remove metal flakes and contamination.

� Connect the RF OUTPUT PORT to the PIM SOURCE supplied in the accessory kit.

� Set the MODE SELECT switch to P1 (measure power in carrier 1). Check and adjust the power of carrier 1 using the POWER ADJ. switch, to indicate +43.0 dBm (+0.5/-0.0 dB) on the LED scale.


� Set the MODE SELECT switch to PIM. The measurement level LEDs should indicate a PIM level of -75 dBm ± 3 dB.

� Set the MODE SELECT switch to off.

� Connect the RF OUTPUT PORT to the RF test cable supplied with the accessory kit. Attach the LOW PIM LOAD supplied in the accessories kit to the other end of the RF test cable. A male-to-male RF adapter may be required depending on the test cable used.

� Set the MODE SELECT switch to PIM. The measurement level LEDs should indicate a PIM level at or below -107 dBm. (Only one measurement level LED should be illuminated.)

� Tap the RF connectors on the equipment, RF test cable and LOW PIM LOAD using the adjustable wrench supplied in the accessory kit (or similar metal object.) The measurement level LEDs should continue to indicate a PIM level at or below -107 dBm.

� Set the MODE SELECT switch to off.

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4. PIM Measurements



� Switch the MODE SELECT switch to OFF.

� Using the RF test cable and adapter (if necessary) provided in the accessories kit, connect the component or system under test to the RF OUTPUT PORT.

� Terminate unused ports of multi-port devices with appropriately rated loads. Note in some circumstances the type of load selected can affect the PIM measurement.

� Set the MODE SELECT switch to PIM.

� The measured PIM result is indicated on the LED bar graph.

� Tap all components & RF connectors in the system using the adjustable wrench supplied in the accessory kit (or similar metal object.)

� Switch the MODE SELECT switch to OFF.

� Record the PEAK PIM result displayed through the duration of the test into notes or PC1.

1 PIM tester can be connected to a computer via a D9 serial cable or using a USB to D9 serial port adapter. COM

settings: COM 1, 9600, 8 bit, no parity, 1 stop bit, Xon-Xoff. Data can be collected directly from the iMT using

interface software loaded on the computer.

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Appendix B: iQA Series - 20W PIM Tester

Summitek Model No.

iQA-700L iQA-700H iQA-850 iQA-1900 iQA-1921

Band: 700 MHz Lower

700 MHz

Upper

850 MHz PCS PCS + AWS


728-746 MHz 728-757 MHz 869-894 MHz 1930-1990 MHz 1930-1990 MHz / 2110-2155 MHz

Receive Frequencies

698-716 MHz 776-787 MHz 824-849 MHz 1850-1910 MHz 1710-1755 MHz / 1850-1910 MHz

B.1 Specifications:


, 5th, 7

th & 9

th order




• Residual Intermodulation: <-110dBm/-153 dBc max (-115 dBm/-158dBc typ.)


• Measurement range: -50 to -128 dBm

• Report capability: Data collection / reports generated via embedded computer

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B.2 User Interface

1 AC input, 110-230 VAC, and fuse

2 AC Power on/off switch

3 RF “ON” warning LED


5 LCD touch screen

6 RJ45 LAN port

7 2 X USB ports

5

3

4

6

7

2

1

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8 RF on/off button

9 Test Transmit Frequencies

10 PIM Order / Receive Frequency

11 Transmit Output Powers

12 Alarm Status Indicator

13 Button Bar

14 Power Timer

15 Active Test Point Label

16 Peak PIM level

17 Pass / Fail indicator

18 PIM level

19 PIM level indicator bar

20 Pass / Fail limit

8

9 10 11 12

13

15 16 14

17

18

19

20

USER SCREEN

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B.3 Equipment Verification

� Press the AC POWER button and the instrument will begin its start-up procedure. When the instrument is ready to use the user screen will be displayed.

� Verify that the ALARM STATUS INDICATOR is green and displays “NONE”.

� Verify that the TRANSMIT OUTPUT POWERS, P1 and P2, are set to +43 dBm.

� Verify that the PIM ORDER is set to IM3.



� Press the green RF OFF button. The button will turn red and change to RF ON, indicating that the RF is active. The PEAK PIM LEVEL of the PIM SOURCE should be -75 dBm ± 3 dB (700 & 850 MHz units) or 77 dBm ± 3 dB (AWS & PCS units.)

� Press the red RF ON button. The button will turn green and change to RF OFF, indicating that the RF is inactive.

� Connect the OUTPUT PORT to the RF test cable supplied with the accessory kit. Attach the LOW PIM LOAD supplied in the accessories kit to the other end of the RF test cable. A male-to-male RF adapter may be required depending on the test cable used.

� Press the green RF OFF button. The button will turn red and change to RF ON, indicating that the RF is active. The PEAK PIM LEVEL should be at or below -107 dBm.

� Tap the RF connectors on the equipment, RF test cable and LOW PIM LOAD using the adjustable wrench supplied in the accessory kit (or similar metal object.) The PEAK PIM measurement level should be at or below -107 dBm.


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B.4 PIM Measurements

� Verify that the TEST TRANSMIT FREQUENCIES are set to the Service Provider’s licensed spectrum or set to guard band frequencies. (See chart below) Verify that the PIM ORDER is set to IM3.

Band USA Guard band frequencies

700 MHz 728, 734, 740, 746 or 757 MHz

850 MHz 869, 870, 880, 890, 891.5 or 894 MHz

PCS 1930, 1945, 1950, 1965, 1970, 1975 or 1990 MHz

AWS 2110, 2120, 2130, 2135, 2140, 2145 or 2155 MHz

� Verify that the TRANSMIT OUTPUT POWERS, P1 and P2 are set to +43.0 dBm.

� Verify that the PASS / FAIL LIMIT is set to the required value. (-97 dBm for New Sites or -87 dBm for Existing Sites)

� Set-up report header information by pressing the REPORT button and entering the required SITE, SECTOR, FEEDER and Company/Operator information. Press RETURN when finished to return to the user screen.

� Using the RF test cable and adapter (if necessary) provided in the accessory kit, connect the equipment or system under test to the RF OUTPUT PORT.


� Press SELECT TEST POINT LABEL and choose the label that describes the equipment or system under test and press OK.

� Press the green RF OFF button. The button will turn red and change to RF ON, indicating that the RF is active. The instantaneous PIM LEVEL, PEAK PIM LEVEL and PASS / FAIL INDICATOR will display on the screen.

� Tap all RF connections and components in the system under test using the adjustable wrench supplied in the accessory kit (or similar metal object.)

� Press the RECORD TEST POINT button.


� To review the current test report press the REPORT button.

� To save the current test report select the SAVE AS PDF button on the REPORTS menu. Select D: to save the report to the test set hard drive or select E: (or F:) to save to an inserted USB storage drive and press OK.

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Appendix C: IHA Series – 2W PIM Tester

Summitek Model No.

iHA-850 iHA-1900

Band: 850 MHz PCS


870 MHz, 894 MHz (fixed)

1930 MHz, 1990 MHz (fixed)

Receive Frequency

846 MHz 1870 MHz

C.1 Specifications:


order




• Residual Intermodulation: <-130dBm/-163 dBc max


• Measurement range: -80 to -130 dBm

• Report capability: None

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C.2 User Interface:

1 RF on / off button

2 Battery Check / Display Mode Selection button


4 RF “ON” warning illuminated ring

5 Status LEDs

6 Measurement Level LEDs

2 1 4 6 5 3

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C.3 Equipment Verifications:

� Press the BATTERY CHECK button to verify that the instrument has sufficient charge to perform a test.



� Press and hold the red RF POWER button for 6 seconds. The PIM LEVEL of the PIM SOURCE should be -102 dBm ± 4 dB (850 MHz unit) or -104 dBm ± 3 dB (PCS unit.)

� Verify that no ALARM STATUS LED’s are illuminated. (The “A” STATUS LED indicates that the beeper is turned on and is not a fault.)

� The instrument will automatically turn RF OFF after 30 seconds.

� Connect the RF OUTPUT PORT to the RF test cable supplied with the accessory kit. Attach the LOW PIM LOAD supplied in the accessories kit to the other end of the RF test cable. A male-to-male RF adapter may be required depending on the test cable used.

� Press and hold the red RF POWER button for 6 seconds. The PEAK PIM LEVEL should be at or below -130 dBm.

� Tap the RF connectors on the equipment, RF test cable and LOW PIM LOAD using the adjustable wrench supplied in the accessory kit (or similar metal object.) The PEAK PIM measurement level should be at or below -130 dBm.


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C.4 PIM Measurements:

� Press the BATTERY CHECK button to verify that the instrument has sufficient charge to perform a test.

� Verify that no ALARM STATUS LED’s are illuminated. (The “A” STATUS LED indicates that the beeper is turned on and is not a fault.)

� Using the RF test cable and adapter (if necessary) provided in the accessories kit, connect the component or system under test to the RF OUTPUT PORT.


� Press and hold the red RF POWER button for 6 seconds. The PIM LEVEL is indicated on the LED DISPLAY.

� Tap all components & RF connectors in the system using the adjustable wrench supplied in the accessory kit (or similar metal object.)

o If the LEDs on the display jump when a component or RF connection is tapped, the component or connection may be faulty and should be inspected for defects.

o If the PIM LEVEL of a component is greater than -115 dBm for Legacy components or -125 dBm for New components, the component may be faulty and should be inspected for defects.


� If required, record the approximate PEAK PIM level displayed into notes. (2W test sets are typically used for troubleshooting, not pass / fail measurements.)

summitek pim measurement procedure v1.1

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