Observation 2822251: METEOR M-2 (40069)

Satellites & Observations Observations
1

Regarding Observation 2822251 …
For what it’s worth - this observation from a moxon (turnstyle) antenna with mast amp (minikits eme173 2m) has a minicircuits splitter (ZESC-2-11, 10e6 to 2e9) to share the antenna for satnogs rtl-sdr with a usrp b205mini - this decoded the pass with the usrp - probably redundant sox convert (500 → 288 → 96 KSps) :

record usrp in gqrx at 500e3 samples per second - native format for gqrx is floating complex

$ sox -ef -b32 -r500e3 -c2 gqrx_20200911_132754_137100000_500000_fc.raw -es -b16 -r288e3 m2.wav

~/meteorM2/09112020T0925$ sox -r 288k -c 2 -b 16 -e s m2.wav -t wav meteor_a.wav rate 96k

~/meteorM2/09112020T0925$ sox meteor_a.wav meteor.wav gain -n

~/src/meteor_demod/src/meteor_demod -o meteor.qpsk meteor.wav
looks like a good constellation for most of the pass

~/src/meteor_decoder/medet meteor.qpsk meteor -cd
reading onboard time ok
lots of packets
Total: 70.907028
Processing: 4.680912
Correlation: 11.135599
Viterbi: 50.696815
ECC: 4.283154
Remainder: 0.110550
Packets: 3494 / 4354
Elapsed time: 00:07:04.744

~/src/meteor_decoder/medet meteor.dec meteor_122 -r 65 -g 65 -b 64 -d
Total:        4.430375
Processing:   4.393320
Correlation:  0.000000
Viterbi:      0.000000
ECC:          0.000000
Remainder:    0.037055
Packets:      3494 / 3494
Elapsed time: 00:07:04.744

17662006 Sep 11 09:51 meteor_122.bmp

Only one big dropout in the middle, and a small one in the top half - rest is continuous

meteor_09112020T0925
meteor_09112020T09251552×2204 973 KB

1 Like
2

Hi, I have a question,
how do you get colour onto decoded data aka the image?
do you have a software that does that or is it done manually?

Thanks Paul

3

it is done in the decoding part - there are probably many ways to use these, the one I found for the above is two pass - once you have the qpsk file from meteor_demod :

medet meteor.qpsk meteor -cd                                     -cd Make decoded dump

medet meteor.dec meteor_122 -r 65 -g 65 -b 64 -d      -d  Use decoded dump

-r x APID for red (default: 68)
-g x APID for green (default: 65)
-b x APID for blue (default: 64)

4

Hello, good job!
I would like to know more about the demodulator you use, I appreciate your help.

5

Hi the software demodulator used is from https://github.com/dbdexter-dev/meteor_demod that has a link to the decoder that will need free pascal installed