I’ve received 9k6 signals in 40 seconds intervals on 437.250 following 58921 but was unable to decode it.
One good example:
2025-03-13T10:23:37 437.250 9k6 FM.wav.zip (17.2 KB)
(Just remove the suffix .zip)
Please try for yourself.
Could it be NExSat-1, or maybe DRO-L?
73
Daniel
Created some obs to save IQ recordings, lets see if we can decode them.
It is possible this is BPSK and not FSK
I also recorded it in USB, but looking at the wave form of the FM recording, it looks like FSK.
Using this fsk.grc.zip (1.4 KB) fsk gnuradio flowgraph
I get this
***** VERBOSE PDU DEBUG PRINT ******
((packet_ len . 136))
pdu length = 136 bytes
pdu vector contents =
0000: ff 0f 51 a5 a1 aa aa aa aa aa aa aa aa aa aa aa
0010: aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
0020: 0a 54 af f3 33 2a 1a cb ae 01 71 e5 5b af 44 dd
0030: 62 78 98 8a fa 71 7d 9c 1c 6f b4 f8 6d 35 e6 a5
0040: d1 86 43 c8 5d b1 11 a3 24 d7 75 a4 54 e0 a5 94
0050: fb ce 30 15 35 f3 cd 1e dc 89 b5 d0 28 f7 e2 b2
0060: 02 cb a2 4e b5 3b fb 51 1f 97 0d ef 4d a7 79 96
0070: ee 3b c3 f2 25 66 5c 6c 8f 48 a0 5d ab 59 98 20
0080: a8 a9 5e 83 46 d8 78 8c
************************************
for Preamble (AA), HDLC-Flag (7E).wav.zip (16.8 KB)
It’s showing clearly the 0xaa preamble.
Should/Could the next byte be the 0x7e HDLC flag?
