manual for preparation of the telemetry stations at...

Manual for preparation of the Main Telemetry Station and Experimenters Room for Student Rocket Operations

Main Telemetry Station Manual

Amund Nylund and Kjetil Henninen of 12Last update: 15.10.2006


1. IntroductionAt Andøya Rocket Range (ARR) we use two telemetry stations for receiving and processing data from student rockets. The Main Telemetry station (or Main TM station) uses a 10’ and a 20’ parabolic antenna for receiving signals from the rocket. These antennas are commonly used by ARR during scientific rocket campaigns. During the student rocket campaign some of the Main TM station will be set up and operated by ARR staff, and some of the preparations will be done by students under supervision of the group leader. The Student telemetry station is used as back-up during student rocket campaigns, and for educational purposes in off-campaign matters.

Figure 1 shows a typical block scheme for a telemetry station with the most important equipment needed to receive and process data from a sounding rocket. This manual will give a description on how to set up the main telemetry stations for a student rocket launch. An introduction to the main components of a telemetry station will be given before the telemetry stations are prepared.

Figure 1



2. Main telemetry stationPreparation of this telemetry station is comprehensive and operators under campaigns have lots of experience and knowledge about the equipment in the station. In the following we will see how to set up some of the station to receive and process data from the student rocket.

2.1 Receiver setupThere are two Microdyne 1100 receivers (Figure 2) in the Main telemetry station. One for right-hand circulated polarized (RHCP) signals, and one for left-hand circulated polarized (LHCP) signals. The 10’ antenna receives both kinds of signals on 2279.5 MHz from the rocket antennas. On the 10’ antenna pedestal the frequency is down converted with a frequency of 1985 MHz. Subtract this frequency from the received frequency and set the receiver to the right frequency. At the Main TM we usually use more receivers for back-up. The Multicouplers are signal distributors to the different receivers. Always remember to switch the multicouplers on when we use the receivers. Other receiver functions will be explained by your group leader.

Tasks: Switch on both multicouplers. Switch on all receivers. Tune in to the correct frequency. Make sure the demodulation is set to FM. Set 2nd LO mode to XTAL. Set AGC Time Constant to 100 ms

For the 1400 receiver select: Bandwidth to 2Mhz Video bandwidth 500kHz Loop bandwidth to 20 (by pushing the arrow symbol) Antisideband to 3 (by pushing enable button)

Figure 2

Microdyne 700-MRB Receivers



The receivers need to be configured according to the signals from the rocket payload.

Frequency1. Set RF FREQ to “294.5 MHz”. This is the same frequency as the Transmitter (Tx) in

the rocket payload.2. Set IF BW to “2.4 MHz”. Bandwidth of the intermediate frequency (IF).3. Set B/S to “NO Bs/Sc”. Because there are no Bitsync in the receiver.4. Set RCD FREQ to “No Pre Det”.5. Set VID BW to “500 kHz”6. Set 2nd LO to “.0 K”

Demodulation

1. Set FM BW to “100 4 FM”. (increase to 1.25 MHz “100 3 FM if no sync)2. Set Loop BW to “100 4 FM” . (increase to 1.25 MHz “100 3 FM if no sync)3. Set SWEEP RNG to “250 kHz”.

Other parameters1. Make sure 2nd LO mode is set to “XTAL”.2. Make sure AGC TC is set to “100 ms”.3. Make sure SWEEP EN is on.4. Make sure VID GAIN is between -15 dB and -20 dB.

- Microdyne1620-PCR Diversity Combiner

The main tasks of the combiner are to pass on the best signal from the receivers (LH or RH) and to reduce various unwanted signal effects like modulation, polarization and distortion.

Frequency1. Set IF MON to “2.4 MHz”. This is the frequency received from the receivers.2. Set B/S to “NO Bs/Sc”. Because there are no Bitsync in the receiver.3. Set RCD FREQ to “No Pre Det”.4. Set VID BW to “500 kHz”5. Set Comb LO to “.0 K”6. Set Demod LO to “.0 K”

Demodulation1. Set FM BW to “100 4 FM”.2. Set Loop BW to “100 4 FM”3. Set Demod Mode to “100 4 FM”



2.2 Bit SynchronizerThe Bit Synchronizer locks on to the bit stream from the combiner and give out NRZ-code and clock (CLK).

Tasks: Switch on Bit Synchronizers Set bit rate to: 256 kbit/s Set code to: Bi-Phase – L (Biφ-L) Make sure Data Polarity is set to Normal, Detection is set to I/D, Loop Width is set to

0.3% and that channel 1 is used. Select source:1

2.3 PatchingInstead of using cables from and to every single component in the TM station and other stations at ARR, we use the two patch panels to connect the different components to each other. An overview of the patch panels and how to patch signals are described in the Appendix 1 and 2. In brief, patching signals includes:

- Data to the different tracks on the tape recorders. Group leaders will give an introduction to which signals to be recorded.

- Signals from either Combiner or Bit Synchronizer to one or more Eidel PCs in Experimenters room.

- Signals according to the block scheme in Figure 1.

Do not hurry with the patching. Let the whole group be aware of what signals to be patched. Your group leader will explain the signal patching in details.

It is important to be careful with the patching wires and when you put the patching plugs on the patch panel. The patching plugs are thin and break easily.

Tasks: Use Appendix 1, 2 and Figure 3 to patch signals on patch board 1 and 2.

2.4 Format set up on VTS.The PCM format needs to be set up on the Visual Test System (VTS) Computer. The principle is the same as for EE315 but the VTS is more complex, so the setup on VTS will be demonstrated by the group leader or ARR staff.

2.5 Slant range calculationsSlant range is the method of calculating the flight profile of the rocket. This is usually done in a different station at ARR called Trajectory and Position System (TPS), but it needs information from the Main TM to do this calculations. The group leader will explain this in brief at the station.



Figure 3



Experimenters room setupPatching from Main TM to the experimenters room are a part of the fixed setup at ARR. Signals may also be patched to the different experimenters desks through patch panel 1. The number of computers used in the Experimenters Room varies from campaign to campaign, and how many experiments that needs to be monitored.

Tasks: Make sure the Line Drivers and Word Selectors in the Main TM are switched on. Patch output signals (NRZ and CLK) from the different desks to the respectively

computers in the experimenters room.

3.1 The student rocket PCM format.To visualize data from the rocket ARR uses the Eidel software and Visual Telemetry System (VTS). Before we can set up the computers we need to know the format is generated in the rocket payload PCM encoder. The format is shown in Table 1.

Bitrate 256 kbit/sPCM code BiPhase-Level (Biφ-L)Sync-word 16 bit, hex:EB90, bin:1110 1011 1001 0000Frame counter 16 bit (Word 02 is MSB, Word 03 is LSB)Words per Frame 14Frame per Format 1Analogue channels 8Analogue word length 8 bitDigital channels 2Digital word length 8 bit

Table 1

Data from the rocket are coded by the encoder in the rocket payload. This code is called Pulse Code Modulation (PCM). This code has to be decoded by the visualization software. The PCM code for the student rocket is Biφ-L. How this and another code called NRZ represent binary codes are shown in Figure 4.

Figure 4

Details of the different word allocation of the PCM format are shown in Table 2.

Word Allocation Data Comment

00 Frame Sync (EB)01 Frame Sync (90)02 Frame Counter MSB



03 Frame Counter LSB04 Analogue Ch 0 Temperature PCB-card05 Analogue Ch 1 Temperature Nose06 Analogue Ch 2 Magnetometer Spin07 Analogue Ch 3 Pressure Sensor08 Analogue Ch 4 Accelerometer Z09 Analogue Ch 5 Accelerometer Y10 Analogue Ch 6 Photo Transistor11 Analogue Ch 7 Payload Battery Voltage12 Digital Ch 013 Digital Ch 1 First bit pulled high at

lift-offTable 2

3.2 Format set up on Eidel (EE315-DOS version and EE350-Windows version)Some of the Eidel card at ARR comes with integrated Bit Synchronizer (Bit Sync) and some does not. Computers with integrated Bit Sync will have input signals directly from the combiner (or from the Biφ-L output from the Bit Sync). Eidel cards without Bit Sync will of course have input signals from an external Bit Sync. The computers in the Experimenters Room come with different versions of the Eidel software. The following chapter illustrates the process of Eidel setup in brief. For details about the Eidel software we refer to the manuals that you will find in the Experimenters Room.

Run the program and choose the “Format Setup”. Set the correct parameters according to Table 1. Figure 5 shows an example of the format setup in EE315. Do not use the parameters in the figure.

Figure 5

Choose the “Data Setup and Display” on EE315 or “Signal Setup” on EE350 to set the rest of the parameters in Table 2. Set up your displays in such way that the analogue channels first


Manual for preparation of the Main Telemetry Station and Experimenters Room for Student Rocket Operationsshow its decimal value, and then the special scale value. (NB! In EE315 the special scale edit comes up if you push F9). The special scale value refers to the sensors voltage output level. This voltage has to be converted to a different value, e.g. bar, meter, g, tesla or gauss. To visualize the sensor output in a special scale you will need to put in some scaling formulas. Calculation of these formulas must be based on the bit resolution and sensor output. Thus, study the different sensor data sheets and try to figure out what the formula means. The different formulas and constants are listed in Table 3. Note that these formulas have to be calibrated when the payload and experimental group are finished with the sensors.

During the payload testing you will see if the Eidel computers are correct configured. Show the Experimental group how they can monitor their sensors during the campaign.

4. Ready for campaignDuring the final testing you will see if the Main TM station and the Experimenters Room are working properly. If not, you will have to go through the whole setup together with your group leader, and troubleshoot.

Good luck on the campaign!



Sensor Formula Scale name Notes Scale Min value

Scale Max value

Low limit

High limit

Constants

Temperature PCB

((A/e)*g)/f C (Celcius degrees)

f = 0.05 -10 120 0 100 A = word nre = 256f = see notesg = 5h = 44307.69396i = 38*10-3

j = 0.190284k = 130l = 3.2m = -0.48 1

n = 0.0045o = 5

Temperature Nose

((A/e)*g)/f C (Celcius degrees)

f = 0.05 -10 120 0 100

Magnetic Field ((A/e)*g)*o kA/m 2 Optional3 -10 10 -10 10

Pressure (((A/e)*g)-m)/n mbar (millibars)

Optional4 0 1100 0 1015

Acceleration Z (((A-k)/e)*g)/i g (m/s2) -60 60 -50 50Acceleration Y ((A-k)/e), k=A(0), e=16 g (m/s2) -5 5 -2 2Photo Transis. ((A/e)*g)*l Intensity

Battery Voltage

((A/e)*g)*l V (Volts) 4 16 5.2 12

Altitude h*((1-((((A/e)*g)-m)/n)^j) m (meter) 0 10000 0 9000Battery Voltage

((A/e)*g)*l V (Volts) 4 16 5.2 12

Umbilical A IN (marks lift-off)

Mask first bit

0 1 0 1

Table 3

1 This value must be corrected for the barometric pressure at launcher during the rocket campaign. The correction formula is based on the linear scale pressure output from the pressure sensor datasheet. This formula is: m = ((Output voltage) – 0.0045*(Known Pressure))2 1 kA/m = 1.25 mTesla (in air), 1 mT = 10 Gauss. In this formula the value is not concurrent with units.3 The magnetometer used on this sensor is only to register rocket spin variations.4 Altitude is calculated from the pressure value.



Appendix 1

Patching board nr 11K– 9L1S – 10E

6Q – 2R 11A – 12J11B – 12P11C – 12Q11E – 20L11F – 15W11H – 15S11J – 10N

20J – 9V20K – 14S20L – 11E

2K – 9N2R – 6Q2S – 10G2X – 21C

7E – 10A7A – 18A7J – 23K

12G – 9A12J – 11A12P – 11B12Q – 11C12U -9C

21A – 15R21B – 15V21C – 2X

3M – 10L 8J – 23H 14S – 20K 23K – 7J23L – 15Q23H – 8J 23J – 15U

4C – 9G4K – 10C4R – 5S

9A – 12G9C – 12U9G – 4C9J – 18C9L – 1K9N – 2K9Q – 15X9V – 20J9W – 15T

15Q – 23L15R – 21A15S – 11H 15T – 9W15U – 23J15V – 21B15W – 11F15X – 9Q

5A – 18B5Q – 10K5S – 4R

10A – 7E10C – 4K10E – 1S10G – 2S10K – 5Q10L – 3M10N – 11J

18A–7A18B-5A18C–9J

Figure 6 – Patch board nr 1 Figure 7 – Overview patch board nr 1



Appendix 2

Patching board nr 21E – 4C1U – 2E1S – 5Q1T – 1W1W – 1T

2E – 1U

3F-8A

6Q – 4R

7F - 16T

11J – 20U

4C – 1E4E – 8E4R – 6Q4S – 5S4T – 9V4U – 9W4V – 9Q4W – 12G4X – 12Q

8A – 3F8E – 4E8F – 5V

12G – 4W12H-20T 12Q – 4X

20T – 12H20U – 11J

5Q – 1S5S –4S5V – 8F

9Q – 4V9V – 4T9W – 4U

16T - 7F

Figure 8 – Patch board nr 2

Figure 9 – Overview patch board nr 2


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