Hubble-6 Decode Help?

[K4KDR]

As illustrated in observation

https://network.satnogs.org/observations/14484170/

… the network is robustly decoding the 4k8 AX.25 GMSK downlink from Hubble-6.

I am left with quite a mystery in that I have tried everything in my toolbox without success with this downlink.

Could someone please share the particulars of how SatNogs is successfully decoding this downlink? Thanks very much!

[PE0SAT]

Good afternoon Scott,

This Yaml works with audio ogg files, I have tried an IQ yet.
Use this observation as input.

name: HUBBLE-6
alternative_names: LILO
norad: 98594
data:
  &ax25 AX.25 Telemetry:
    telemetry: ax25
  &endurosat Endurosat Telemetry:
     unknown
transmitters:
  4k8 FSK AX.25 downlink:
    frequency: 401.100e+6
    modulation: FSK
    baudrate: 4800
    framing: AX.25 G3RUH
    data:
    - *ax25
  4k8 FSK Endurosat downlink:
    frequency: 401.100e+6
    modulation: FSK
    baudrate: 4800
    framing: Endurosat
    data:
    - *endurosat

gr_satellites HUBBLE-6.yml --wavfile 11821287.ogg --samp_rate 48e3

***** VERBOSE PDU DEBUG PRINT ******
((transmitter . 4k8 FSK Endurosat downlink))
pdu length =         96 bytes
pdu vector contents = 
0000: 5f fe f1 6e 90 a0 bc a5 6a fa d1 c3 7f c5 12 9d 
0010: 0f c5 48 dd 42 fe 00 cf 26 3a 66 96 70 c2 86 03 
0020: f6 67 c8 1a 4e 03 6d 9d c5 b8 13 f7 9c 28 a6 34 
0030: 9a f9 48 42 8a a3 45 cf 54 b8 4b 72 38 30 35 b1 
0040: eb 6c e9 d2 43 67 bd 62 a2 31 d8 af cc 01 8c b2 
0050: a7 d9 84 de 25 27 ea 47 fb f6 c9 80 7c 47 7a d4 
************************************
-> Packet from 4k8 FSK AX.25 downlink
Container: 
    header = Container: 
        addresses = ListContainer: 
            Container: 
                callsign = u'ESGS01' (total 6)
                ssid = Container: 
                    ch = True
                    ssid = 0
                    extension = False
            Container: 
                callsign = u'HUBBL6' (total 6)
                ssid = Container: 
                    ch = True
                    ssid = 0
                    extension = True
        control = 0x03
        pid = 0xF0
    info = b'\xa2\x11\x013\x94\x04\x01(\x00\x00\xc1\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' (total 64)
-> Packet from 4k8 FSK AX.25 downlink
Container: 
    header = Container: 
        addresses = ListContainer: 
            Container: 
                callsign = u'ESGS01' (total 6)
                ssid = Container: 
                    ch = True
                    ssid = 0
                    extension = False
            Container: 
                callsign = u'HUBBL6' (total 6)
                ssid = Container: 
                    ch = True
                    ssid = 0
                    extension = True
        control = 0x03
        pid = 0xF0
    info = b'\xa9\x11\x013\x9b\x04\x019\x00\x00/\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00E\x00\x01u#T' (total 64)

I am not sure on the Endurosat framing.

Jan | PE0SAT

[K4KDR]

Thanks very much for the reply!

What kills me is that a standard FSK / AX.25 flowgraph decodes the audio from a good SatNogs observation perfectly.

… however, my own recordings, no matter how strong & clear, do not. I can’t figure out what I am doing differently… I’ve decoded thousands of other 4k8 packets just fine.

I do notice that the SatNogs Observation audio results in a much more narrow spectrum than my own audio recordings, so I didn’t know if it was being filtered, using USB demod, or what. Quite a mystery that I’ve spent endless hours on!

[PE0SAT]

I also gave the UZ7HO sound modem a try

Maybe something changed in the sample rate on your side?

[K4KDR]

Many thanks for checking!

I sure don’t know… everything else continues to decode just fine w/ my normal GQRX configuration. Will keep working on it.