Observation 4887748: Binar-1 (99520)

spacerock_engineer · October 21, 2021, 3:42pm

I can see a very faint beacon in this waterfall just before 400 seconds. I am not sure if that is sufficient to warrant a “good”. Thoughts?

w6msu · October 21, 2021, 4:27pm

Perhaps not “great” but certainly good.

I would say a good catch on your part. HI

73,
Guy W6MSU

fredy · October 21, 2021, 4:42pm

There is also another one at ~270s. However these signals are not the expected GMSK9k6. Except if we missed any info about the Binar-1 mode and rate, I would say that this is another satellite. But we need to find which one, I’ll try with ikhnos during the weekend.

If you see any other similar please open a thread in order to have more observations to verify that this is another satellite or Binar-1.

fredy · October 21, 2021, 4:45pm

I’ve just did a quick look on the same time, and there is this one SatNOGS Network - Observation 4891929. Here the signal is clear and it looks that follows pretty well the TLE set. So it may actually be Binar-1… but we need to make sure.

spacerock_engineer · October 21, 2021, 6:48pm

It does appear to be Binar-1. (For context I am the project manager.)

Just before this observation SatNOGS Network - Observation 4887716 we sent an instruction to the satellite to enable a safemode (changing the data rate to 1200 and setting the cadence to 15s). Unfortunately I had my station set not to record below 10 deg, so I missed the first instruction set which was sent, but you can see the follow ups coming from the university groundstation.

Is there a way to change the mode on observations?

PE0SAT · October 21, 2021, 7:10pm

Good to see that there is progression.

I tried to decode this observation with gr_satellites and an altered satyaml file but wasn’t able to decode the signal.

name: BINAR-1
norad: 99520
data:
  &tlm Telemetry:
    unknown
transmitters:
  1k2 FSK downlink:
    frequency: 435.810e+6
    modulation: FSK
    baudrate: 1200
    framing: BINAR-1
    data:
    - *tlm
  9k6 FSK downlink:
    frequency: 435.810e+6
    modulation: FSK
    baudrate: 9600
    framing: BINAR-1
    data:
    - *tlm

inspectrum -f cs16 -r 48000 BINAR-1.wav

Then I had a look at the file (converted from ogg to wav) with inspectrum, I can’t really find some data in there.

Where you able to decode this observation?

Jan PE0SAT

PE0SAT · October 21, 2021, 7:16pm

There is now also a 1200 baud transmitter.

spacerock_engineer · October 21, 2021, 7:20pm

Not in this one, but in the clearer signals we can. It is 3 am here in Perth, Australia. Tomorrow morning we can share what we have.

Is it possible to reassign the existing ones from the 9k6?

I look forward to continuing this discussion, but for now I am going to sign off. Thanks all!

fredy · October 21, 2021, 8:01pm

All the future observations of Binar-1 have been changed to the new 1k2 trasmitter. The 9k6 one has been temporarily set to inactive.

m0roj · October 22, 2021, 4:48pm

To quote SatNOGS Wiki on the subject:
Good if the satellite is seen in the waterfall at all.
I can see it - just - so rated Good in my book.

PE0SAT · October 22, 2021, 5:05pm

To the BINAR-1 Team,

gr-satellites BINAR-1 1k2 support Pull Request is approved I am only not successful in decoding the 1k2 signals.

Can anybody of the team please share some details on the signals send by the 1k2 transceiver.

PE0SAT · October 22, 2021, 6:18pm

To the Team:

Do these make sense?

* MESSAGE DEBUG PRINT PDU VERBOSE *
((transmitter . 1k2 FSK downlink))
pdu_length = 76
contents = 
0000: 4b fe f1 6e 90 a0 bc a5 6a fa f1 fe ce 45 2a 26 
0010: 98 09 d7 e8 fe 48 88 03 11 60 f5 9b a7 a3 3a db 
0020: 1e 75 78 a5 de f7 87 4b 60 7c 97 5e 56 82 94 7f 
0030: 0a b7 a8 88 64 2d 78 68 52 69 88 84 dc e0 f0 a8 
0040: 65 e5 15 b4 d6 af eb 37 c6 67 05 00 
***********************************
* MESSAGE DEBUG PRINT PDU VERBOSE *
((transmitter . 1k2 FSK downlink))
pdu_length = 76
contents = 
0000: 4b fe f1 6e 90 a0 bc a5 6a fa f1 fe ce 45 2a 26 
0010: 98 09 d7 e8 fe 48 88 03 11 60 f5 9b a7 a3 3a db 
0020: 1e 75 78 a5 de f7 87 4b 60 7c 97 5e 56 82 94 7f 
0030: 0a b7 a8 88 64 2d 78 68 52 69 88 84 dc e0 f0 a8 
0040: 65 e5 15 b4 d6 af eb 37 c6 67 05 00 
***********************************
* MESSAGE DEBUG PRINT PDU VERBOSE *
((transmitter . 1k2 FSK downlink))
pdu_length = 76
contents = 
0000: 4b fe f1 6e 90 a0 bc a5 6a fa f1 fe ce 45 2a 26
0010: 98 09 d7 e8 fe 48 88 03 11 60 f5 9b a7 a3 3a db 
0020: 1e 75 78 a5 de f7 87 4b 60 7c 97 5e 56 82 94 7f 
0030: 0a b7 a8 88 64 2d 78 68 52 69 88 84 dc e0 f0 a8 
0040: 65 e5 15 b4 d6 af eb 37 c6 67 05 00 
***********************************

Remark by EA4GPZ:

CRC-16 at the end is stripped. 0x55… preamble and 0x7e syncword are stripped as well. The rest of the frame (including the length field, which you can see as 0x4b = 75 here) is as over-the-air.

K4KDR · October 22, 2021, 8:20pm

Does the TLE for NORAD #49272 continue to be the best track for Binar-1?

Also, are these downlinks being seen on 437.292? There had been another frequency listed at some point related to this satellite as well.

Thanks!

-Scott, K4KDR

5ch4um1 · October 22, 2021, 10:40pm

I am getting the same data it seems, also a 0xAA… preamble, then 0x7e, if 4b is the length in decimal it’s probably supposed to be 75 then, but one thing i don’t understand: i got this via the phase plot, and i can’t see anything that looks or sounds like fsk in the recording?

PE0SAT · October 23, 2021, 7:48am

SatNOGS is still using object 49272 and the frequency is 437.292 and not 435.810.

PE0SAT · October 23, 2021, 7:52am

It seems because you and I are using a FM demodulated audio file the inspectrum behaviour is different and not as expected. Dani was mentioning NRZ in the twitter tweet (https://twitter.com/ea4gpz/status/1451599862278017038).

5ch4um1 · October 23, 2021, 1:29pm

uhm, i always thought an fm demodulator just “translates” the rf signal to audible frequencies? like with sstv e.g. ? Assuming fsk refers to some form of binary fsk, what is the difference ( i think you call this deviation) between the two frequencies then? why can’t i see that in the audio? and why do i get the same data as you, but from a phase plot?

dbusan · October 26, 2021, 1:08am

The current beacon setup is a fixed message every 150 seconds to conserve battery and allow it to charge enough for operations, but still provide us with a visible signal whenever it comes overhead. For example like in this observation:

SatNOGS Network - Observation 4908958

These particular transmissions, the periodic beacon containing a fixed message from the comms module, are AX.25 encoded UI frames. I believe they should be decodable with off-the-shelf G3RUH demodulators. See image below for the encoding description

Scrambling polynomial is 1+x12+x17.

Hope this helps.

Daniel

EA4GPZ · October 26, 2021, 3:36pm

Thanks for the information! I have just modified the SatYAML file in gr-satellites to try to decode frames using AX.25 G3RUH as well. I’m getting good decodes with

gr_satellites BINAR-1 --wavfile satnogs_4887716_2021-10-21T09-18-25.ogg --clk_bw 0.3

PE0SAT · October 26, 2021, 6:49pm

Thanks Daniel,

One remark for those that want to give this a try, ogg files are only supported by gr-satellites that uses GNURadio 3.9 for other versions first convert the ogg to wav ffmpeg -i <input.ogg> <output.wav>