How to decode AAUSAT-II FFSK/MSK telemetry
JE9PEL translated into English from http://www.dk3wn.info/sat/afu/sat_aau.shtml
Status:
Actively, but very quiet signals
A Telemetrieburst is sent of all 30 sec.
A Burst is approximately 1.6sec long.
The MSK modulation (Minimum Shift Keying) is a variation of the
Frequenzumtastung (FSK) and frequently is called also FFSK
(Fast Frequency Shift Keying). MSK therefore can as phases or
frequency modulation, modulation index = 0.5, is viewed.
The phase turns during the time of a Bitlange 90 deg.
MSK is rather sensitive opposite flush and disturbances.
The signals of AAUSat are very weak and you needs to record
a good reception installation noiseless about the signal.
Martin Laabs, DM1EF has the name of the SOMP-Cubesat Studtentengruppe
of the TU-Dresden FFSK(= MSK), written sound card to demodulator
for the AAUSAT-II.
There is the Sourcecode of the FFSK/MSK-Demodulator here:
http://rcswww.urz.tu-dresden.de/~stard/msk_demod-0.1.tar.gz
The program expects a WAV file signed in the format 32 bit, mono,
and little endian, sample rate 48000 bit/s. most audio files must
therefore be converted only in this format. This task takes over
a fantastic tool by the name of SOX, Sound eXchange. the Command
Line Utility can be downloaded here:
http://sox.sourceforge.net/
-----------------------------------------------------------------
sox aausat_29042008_0815.wav -t raw -c1 -r48000 -L -s -4 temp.wav
-----------------------------------------------------------------
With this command, the file is converted aausat_29042008_0815.wav
into the necessary format and is stored as temp.wav.
with SOX of converted WAV file, sample rate 48000,
Now, Martin's tool is put into action. The program decodes the WAV
file (AX.25 packet) and stores the data as binary file.
So, an AAUSat looks telemetry frame:
I, DK3WN, compiled the source code under Visual C++ Express 2008.
Therefore, it's necessary Microsoft .NET Framework version 3.5 Runtime.
The Demodulator.exe file, including SOX and decoder_demo, for WindowsXP
you finds under
http://www.dk3wn.info/files/demodulator.zip
----------------------------------------
demodulator temp.wav raw_beacon_data.bin
----------------------------------------
To the decoding of the AX.25 packet, the AAUSAT-II team itself
wrote a software. You finds these here:
http://aausatii.space.aau.dk/upload/decoder_demo.zip
----------------
decoder_demo.exe
----------------
The result is a text file in which the individual telemetry values
are stored as beacon.txt.
Audio files
Receptions of the beacons of the AAUSAT-II to the tests you finds here:
http://www.control.aau.dk/~kresten/stuff/aausatii/
Homepage and further Info's:
http://www.aausatii.aau.dk/
AAUSAT-II FFSK/MSK supplementary test by JE9PEL
1. Install Microsoft .NET Framework 3.5
http://www.microsoft.com/downloads/details.aspx?familyid=333325FD-AE52-4E35-B531-508D977D32A6&displaylang=en
2. Install demodulator.exe
http://www.dk3wn.info/files/demodulator.zip
3. Install decoder_demo.exe
http://aausatii.space.aau.dk/upload/decoder_demo.zip
4. Record as WAV file from AAUSAT-II FFSK/MSK
http://www.dk3wn.info/sounds/aausat_29042008_0815.wav
5. Convert to WAV using by sox.exe
sox.exe aausat_29042008_0815.wav -t raw -c1 -r48000 -L -s -4 temp.wav
6. Convert to BIN using by demodulator.exe
Demodulator.exe temp.wav raw_beacon_data.bin
7. Convert to TXT using by decoder_demo.exe
decoder_demo.exe (Enter)
8. Then saved automatically as beacon.txt
| Header | Valid | CDH Mem | LOG/FLASH | EPS Thresholds PDUsta Thresholds_CDH/Warn | ADCS | COM packets | PL
| Bat SW HAM Sponsor | LEACP | SW Boots Uptime CurrentTime Free Largest Temp1 Temp2 | Free Stat | I_Bat V_SA BAT1_T BAT2_T V_BAT I_PCU T_PRU V5_M V3_M T_BAT V_BATs V_BAT0 V_BAT1 V_BAT2 V_BAT3 123456 TEMP V_BAT0 V_BAT1 V_BAT2 V_BAT3 | Mode Gyro Temp Mag Bdot Act | LastRSSI AvgRSSI RXtot RXok TX HFerr Temp |
--------------------+--------------------------------------------+-------+--------------------------------------------------------------------------+---------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------+--------------------------------------------------------+-----------------------
Wed May 21 13:16:40 | 8.4 DFL ------ Den Obelske Familiefond | 11110 | 00 0 120s Thu Jan 01 09:02:00 1387936 1387840 63.01 62.36 | 1376256 01 | -93.55 4.38 11.29 10.00 8.39 170.97 11.61 5.12 3.38 60.00 6.50 6.79 7.30 7.40 7.50 101000 1 6.96 7.46 7.57 7.67 | 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 | -172.0dBm 0 0 0 3 -73.0 10.37 | -67.84 -67.84 -67.84
AAUSAT-II FFSK/MSK burst length
AAUSAT-II FFSK/MSK beacons
I decoded 'aausat_26052008_2020utc.wav' (4.5MB) which was received
by DK3WN/Mike Rupprecht on 26 May 2008. I used the following technical
skill, then I got four telemetry data as follows.
1. Install Microsoft .NET Framework 3.5
2. Install demodulator.exe
3. Install decoder_demo.exe
4. Record as WAV file from AAUSAT-II FFSK/MSK
5. Convert to WAV using by sox.exe
sox.exe aausat_26052008_2020utc.wav -t raw -c1 -r48000 -L -s -4 temp.wav
6. Convert to BIN using by demodulator.exe
Demodulator.exe temp.wav raw_beacon_data.bin
7. Convert to TXT using by decoder_demo.exe
decoder_demo.exe (Enter)
8. Then saved automatically as beacon.txt
| Header | Valid | CDH Mem | LOG/FLASH | EPS Thresholds PDUsta Thresholds_CDH/Warn | ADCS | COM packets | PL
| Bat SW HAM Sponsor | LEACP | SW Boots Uptime CurrentTime Free Largest Temp1 Temp2 | Free Stat | I_Bat V_SA BAT1_T BAT2_T V_BAT I_PCU T_PRU V5_M V3_M T_BAT V_BATs V_BAT0 V_BAT1 V_BAT2 V_BAT3 123456 TEMP V_BAT0 V_BAT1 V_BAT2 V_BAT3 | Mode Gyro Temp Mag Bdot Act | LastRSSI AvgRSSI RXtot RXok TX HFerr Temp |
--------------------+--------------------------------------------+-------+--------------------------------------------------------------------------+---------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------+--------------------------------------------------------+-----------------------
Tue May 27 22:54:49 | 8.3 DFL ------ Texas Instruments | 11110 | 00 0 2460s Thu Jan 01 09:41:00 1283936 1283872 45.44 44.76 | 1376256 01 | -93.55 3.07 7.42 5.81 8.35 158.06 6.13 5.12 3.38 60.00 6.50 6.79 7.30 7.40 7.50 101000 1 6.96 7.46 7.57 7.67 | 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 | -172.0dBm 0 0 0 81 -73.0 2.12 | -67.84 -67.84 -67.84
Tue May 27 22:54:49 | 8.3 DFL ------ Flemming Freese Bjerre | 11110 | 00 0 2490s Thu Jan 01 09:41:30 1283776 1283680 45.83 44.76 | 1376256 01 | -74.19 3.05 7.10 5.81 8.34 187.10 5.81 5.12 3.38 60.00 6.50 6.79 7.30 7.40 7.50 101000 1 6.96 7.46 7.57 7.67 | 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 | -172.0dBm 0 0 0 82 -73.0 2.12 | -67.84 -67.84 -67.84
Tue May 27 22:54:50 | 8.3 DFL ------ Compower | 11110 | 00 0 2520s Thu Jan 01 09:42:00 1283584 1283488 45.83 45.16 | 1376256 01 | -48.39 3.03 7.10 5.81 8.33 132.26 5.81 5.12 3.38 60.00 6.50 6.79 7.30 7.40 7.50 101000 1 6.96 7.46 7.57 7.67 | 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 | -172.0dBm 0 0 0 83 -73.0 2.12 | -67.84 -67.84 -67.84
Tue May 27 22:54:50 | 8.3 DFL ------ Jesper Abildgaard Larsen | 11110 | 00 0 2550s Thu Jan 01 09:42:30 1283392 1283328 45.44 44.76 | 1376256 01 | -48.39 3.02 7.10 5.81 8.33 122.58 5.81 5.12 3.38 60.00 6.50 6.79 7.30 7.40 7.50 101000 1 6.96 7.46 7.57 7.67 | 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 | -172.0dBm 0 0 0 84 -73.0 2.12 | -67.84 -67.84 -67.84
MSK Decoder for FFSK/MSK
DK3WN wrote another small software (Shell), that processing of the files
essentially relieved. The program msk.exe is started. In the file menu
you open the corresponding WAV file - the rest takes place automatically,
(call of sox, demodulator and decoder_demo.exe). The program is component
of the zip file under http://www.dk3wn.info/files/demodulator.zip
The 'beacon.txt' is automatically generated in the same folder.
AAUSAT-II MSK decoded
I decoded today, 6 July 2008, one MSK packet using this 'msk.exe'.
Downlink telemtry specs:
callsign OZ2CUB
437.425 MHz FFSK/MSK (currently +7kHz (437.432MHz))
1200-9600bps (1200 standard)
AX.25 FM CW TLM (only in safe mode)
http://aausatii.space.aau.dk/eng/
| Header | Valid | CDH Mem | LOG/FLASH | EPS Thresholds PDUsta Thresholds_CDH/Warn | ADCS | COM packets | PL
| Bat SW HAM Sponsor | LEACP | SW Boots Uptime CurrentTime Free Largest Temp1 Temp2 | Free Stat | I_Bat V_SA BAT1_T BAT2_T V_BAT I_PCU T_PRU V5_M V3_M T_BAT V_BATs V_BAT0 V_BAT1 V_BAT2 V_BAT3 123456 TEMP V_BAT0 V_BAT1 V_BAT2 V_BAT3 | Mode Gyro Temp Mag Bdot Act | LastRSSI AvgRSSI RXtot RXok TX HFerr Temp |
--------------------+--------------------------------------------+-------+--------------------------------------------------------------------------+---------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------+--------------------------------------------------------+-----------------------
Sun Jul 06 19:56:03 | PC S | 10100 | 00 46 7077988s Thu Jan 01 09:01:48 1952 51200 0.61 123.36 | 1952 A0 | 133267.74 206.45 13711.61 13877.42 366.42 -480.65 -50.00 242.24 163.78 9917.42 130.98 395.07 400.91 1.57 0.00 000000 192 418.16 87.52 131.27 195.39 | 87 0 0 180 247 34 0 105 211 149 124 228 31 52 0 188 247 34 0 -28 31 52 | -172.0dBm 64008 34 54422 31893 -73.0 -68.00 | -67.84 -67.84 -150.34
AAUSAT-II MSK editing
I edited MSK spectrums using audacity.exe as follows.
Back to Top
Back to CubeSats index
Back to Home Page