Observation 9383691: HyTI (98899)

Satellites & Observations Observations
1

Regarding Observation 9383691 …

Still trying to figure out why our ground stations haven’t seen it, but this was our first contact! Only been able to decode a few packets so far from the audio, but still trying to decode the large number of clearly visible packets.

2

Anybody in the vicinity of Honolulu or Monterey, HyTI appears to be hearing us and starts spewing out packets whenever it passes overhead. If you can collect any data, it will just improve our interaction with the spacecraft.

3

Using the audio from the observation you shared, I decoded the following 9k6 G3RUH/AX25 frame:

***** VERBOSE PDU DEBUG PRINT ******
((transmitter . 9k6 G3RUH FSK downlink))
pdu length =        135 bytes
pdu vector contents = 
0000: a6 9e aa a4 86 8a 60 88 8a a6 a8 92 9c e1 03 f0 
0010: 01 01 6d 00 0c 01 09 08 8c 10 59 af 50 00 00 00 
0020: 00 bb 2a 4a 41 00 00 00 00 bb 48 55 c1 00 00 00 
0030: 00 0c 15 21 41 00 00 00 00 00 82 a0 40 00 00 00 
0040: 00 80 ed a6 40 00 00 00 00 40 b5 b2 c0 00 00 00 
0050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0060: 00 00 00 00 00 28 e8 da 2b 40 9b de 3f 5f 91 33 
0070: 1c 4f 04 54 bf ef e3 11 9a ef 3c 8c bf 91 81 5f 
0080: 69 5a e0 46 3f 88 46 
************************************

-> Packet from 9k6 G3RUH FSK downlink
Container: 
    header = Container: 
        addresses = ListContainer: 
            Container: 
                callsign = u'SOURCE' (total 6)
                ssid = Container: 
                    ch = False
                    ssid = 0
                    extension = False
            Container: 
                callsign = u'DESTIN' (total 6)
                ssid = Container: 
                    ch = True
                    ssid = 0
                    extension = True
        control = 0x03
        pid = 0xF0
    info = b'\x01\x01m\x00\x0c\x01\t\x08\x8c\x10Y\xafP\x00\x00\x00\x00\xbb*JA\x00\x00\x00\x00\xbbHU\xc1\x00\x00\x00\x00\x0c\x15!A\x00\x00\x00\x00\x00\x82\xa0@\x00\x00\x00\x00\x80\xed\xa6@\x00\x00\x00\x00@\xb5\xb2\xc0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00(\xe8\xda+@\x9b\xde?_\x913\x1cO\x04T\xbf\xef\xe3\x11\x9a\xef<\x8c\xbf\x91\x81_iZ\xe0F?\x88F' (total 119)
4

Hi @ejpilger and welcome in the community.

Can you give us some more details about the satellite, so we become more helpful:

  1. I guess with your post you confirm that the satellite transmits at 400.800 MHz, I’m asking as we weren’t sure.

  2. Does the satellite transmit only after command, or it is also beaconing?

  3. Are you 100% sure that the demodulated/decoded frames from the audio, the one you decoded or the one from @PE0SAT above belong to HyIT?

5

Excellent. This packet is consistent with the few packets we have been able to decode ourselves. This particular one is an ADCS State Beacon with the following contents. (some of the numbers are not properly populated). The time stamp is bytes 0x19-0x1c. It is “deciseconds” as a little-endian. This is 1/10s seconds since midnight 2020.

      Beacon 2
      Raw size: 139
  Wrapped size: 119
     Data size: 111
  Packet type: (257) Beacon

Packet data size: 109
Origin: 12
Destination: 1
Chanin: 9
Chanout: 8
Beacon type: (140) ADCSStateBeacon
Beacon size: 109
Beacon time: 2024-04-15T17:54:48Z (60415.746388888889)
Pos X : 3429750
Pos Y : -5579500
Pos Z : 559750
Pos VX: 2113
Pos VY: 2934.75
Pos VZ: -5.311603333027245e+133
Att X : 1.0869444208507424e-321
Att Y : 0
Att Z : 0
Att W : -5.4444631676595066e+147
Att VX: 5.4224765156563617e+96
Att VY: -1.0103719315598041e-249
Att VZ: 2.6534535973645475e+33

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6

In answers to your questions:

  1. It is indeed 400.800 MHz
  2. The satellite will only transmit after being contacted from the ground. Furthermore, for UHF, it only transmits in direct response to command packets, so each of the lines in the waterfall represents a successful command and response. If we could decode them all we would have a wealth of
    information.
  3. We are 100% sure this is us, due to both the AX.25 header and the packet format and contents. (admittedly, we are a bit puzzled by the time which is almost 18 hours after what should have been the starting time of the spacecraft, but what received only about3 hours after deployment).
2 Likes
7

As requested via the SatNOGS Matrix channel, this is what I used to decode the audio from the obs.

First the gr_satellites yml file that I used:

name: HYTI
norad: 98899
data:
  &tlm AX25 telemetry:
    telemetry: ax25
transmitters:
  9k6 G3RUH FSK downlink:
    frequency: 400.800e+6
    modulation: FSK
    baudrate: 9600
    framing: AX.25 G3RUH
    data:
    - *tlm

Then download the audio recording from the observation:

wget https://network-satnogs.freetls.fastly.net/media/data_obs/2024/4/18/14/9383691/satnogs_9383691_2024-04-18T14-15-55.ogg -O 9383691.ogg

When you use gr-satellites based on GNURadio 3.8 you need to convert the ogg file to wav, for this I used ffmpeg. ffmpeg -i 9383691.ogg 9383691.wav

The decode can be done in the following way:

gr_satellites HYTI.yml --wavfile 9383691.wav --samp_rate 48e3 --disable_dc_block --use_agc as an option one can add --hexdump

Jan PE0SAT

4 Likes
8

With help from the MC3 network, we have determined that HyTI is about 50 seconds behind the TLE based on our original state vector. Our new updated best guess at a TLE is as follows:

1 99999U          24111.87377315  .00134493  00000-0  22115-2 0 00005
2 99999 051.6374 239.5834 0001694 041.7080 098.8992 15.51722094004798
1 Like
9

TLE updated in DB and Network. Here is the TLE adjusted to the temporary NORAD ID we use in DB:

1 98899U          24111.87377315  .00134493  00000-0  22115-2 0 00003
2 98899 051.6374 239.5834 0001694 041.7080 098.8992 15.51722094004796
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10

Official TLE now available from Space-Track:

1 59561U 98067WL 24120.41436296 .00029469 00000-0 48552-3 0 9997
2 59561 51.6368 197.1685 0002596 75.0290 285.0987 15.52063073 1719

11

Spacecraft should only be expected to transmit in UHF when in range of Honolulu or Monterey.

1 Like