Comments (5)
The frames output by gr-satellites contain the CSP header. Have you taken this into account?
from gr-satellites.
Hi Dani, yes I believe so. By my understanding, the csp header is the first 32 bits, and hence the first 4 hex pairs, of the pdu. So i am therefore looking at the 5th byte as the start of the data. For example, this is a frame outputted by the gr_satellites command line tool, and it matches the output of a flowgraph i constructed with BPSK demodulator and AX100 deframer blocks into a message debug block, hence i believe the start of the data to be 761a :
***** VERBOSE PDU DEBUG PRINT ******
()
pdu length = 105 bytes
pdu vector contents =
0000: 82 92 3e 00 76 1a 01 cb 65 40 40 ad 00 ac 03 94
0010: 03 a0 02 da 02 ff 03 13 13 13 12 13 13 00 37 00
0020: 0b 20 57 00 17 bc 01 74 7d ff 96 20 95 01 f9 00
0030: a0 5a b0 33 00 17 00 7f 00 5d fc 06 10 bc 24 e6
0040: 0b 44 0e 0e 0e 0e 00 00 00 09 00 07 00 00 00 00
0050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0060: 00 00 00 83 01 eb 83 d5 c5
from gr-satellites.
Yeah. Some fields clearly don't match the documentation, since the telemety identifier isn't 0x3612
, 0x3611
or 0x3610
. However other fields do seem to match the documentation and are in the correct location. For instance, 0x654040ad
is a reasonable UNIX time, and the 6 0x13
or 0x12
bytes are reasonable EPS temperatures.
from gr-satellites.
Indeed, I will caution by saying some fields such as bus voltage are seemingly incorrect at 1V, and would expect them to be much closer to 4.5V -5V for a bus. Also on some of the digipeater packets, the messages seem to contain unreadable symbols. Could this be a case of a poor signal quality, or is there a deeper underlying issue here. For example, in the documentation it says that all of the network link layer is passed through a G3RUH scrambler on the sat side (https://www.s5lab.space/index.php/decoding-ledsat-2/), am i correct that the descrambling occurs as part of the gr-satellites "GOMspace AX100 Deframer" block?
from gr-satellites.
The GREENCUBE SatYAML file in gr-satellites specifies "AX100 ASM+Golay framing". This includes CCSDS descrambling (not G3RUH descrambling!). There is a Reed-Solomon (255, 223) code as part of the decoding. While this is not a 100% reliable test for packet integrity, it gives a reasonable confidence that the decoded packets are correct, specially if the Reed-Solomon decoder corrected only a few or none byte errors. I think that the main thing going on here is that the S5Lab documentation is inaccurate.
from gr-satellites.
Related Issues (20)
- CRC and FEC for PEGASUS (QB50, AT03) demodulated beacons
- IQ input isn't decoding and the audio recording is HOT 30
- No Decoding HOT 13
- No module named 'satellites.bindings' HOT 5
- Can´t Decode QO-100 HOT 5
- Building debian bookworm package fails HOT 4
- PDU Head/Tail crashes with soft bit PDU HOT 1
- flowgraph :warning: Could not find port pdus in: HOT 3
- Mobitex-NX Telemetry forwarding (Error while submitting telemetry: HTTP Error 400: Bad Request) HOT 6
- Wrong vector type instantiation in Fixed Length To PDU block HOT 5
- MRC-100 Decode HOT 11
- Why i cannot decode live??' HOT 10
- Specific flowgraph in gr satellites HOT 2
- Depraction of distutils HOT 1
- Error Runnig Flowgraphs HOT 2
- running gr_satellites SMOG-1 --udp --samp_rate 48e3 fails to create connection in urllib3 HOT 1
- Unable to compile for GNU Radio 3.8 on Ubuntu 22.04 HOT 6
- The deviation option and FM HOT 16
- CCSDS Concatenated Deframer does not run on gnuradio-companion 3.10.7.0 HOT 2
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from gr-satellites.