PSLV-QL with Duchifat-3 - 2019-12-11

Earlier today PSLV-QL has be launched. Among other payloads it will deploy Duchifat-3.

I’ve added the satellite in DB with temporary NORAD ID 99823 and added transmitters as were known in its IARU co-ordination.

Observation have been scheduled with the generated by @cgbsat TLE bellow:

1 84101U          19345.41319444  .00000000  00000-0  50000-4 0    08
2 84101  37.0000 148.0000 0001442   0.0000 140.0000 15.02563222    03 

@HelloWorld you have talked about Duchifat-3 before, may you have some more info about the deployment or the transmitters that will help us to track it, maybe some preliminary TLEs.

We probably have caught it and demodulate it in several observation like:


From what we discussed in the chat, it looks like that it is duchifat-3, 99% sure. As the callsign matches duchifat-1 one.

Seems to be true!
The source callsign decodes to 4X4HSL-1 and the destination callsign to GS-1!
Prior observations of DUCHIFAT-1 decode to 4x4HSL-0 and GS-0. Conventionally the SSID -0 should be removed, so the callsigns for DUCHIFAT-1 decode properly to 4X4HSL and GS. But that is just a side-note :stuck_out_tongue:

Wondering if there is any documentation of the downlink data structure!

Is there an easy way to see 4X4HSL and GS you speak about in the hex or ASCII of ?

Shift the address bytes (bytes 0-5 and 6-11) 1 bit to the right and you get the ASCII for the callsign.


Duchifat-3 changed in network to follow 44853 object.

With my work on the kaitai-struct decoders I also built some useful tools.

You can visit the kaitai Web IDE, click on “New” in the lower left corner, define a filename (omit the .ksy suffix as it is added by the IDE), delete the automatically inserted skeleton and paste the following code:

  id: ax25header
  endian: le

  - id: ax25_frame
    type: ax25_frame
    doc-ref: ''

      - id: ax25_header
        type: ax25_header
      - id: payload
          switch-on: ax25_header.ctl & 0x13
            0x03: ui_frame
            0x13: ui_frame
            0x00: i_frame
            0x02: i_frame
            0x10: i_frame
            0x12: i_frame
            # 0x11: s_frame

      - id: dest_callsign_raw
        type: callsign_raw
      - id: dest_ssid_raw
        type: ssid_mask
      - id: src_callsign_raw
        type: callsign_raw
      - id: src_ssid_raw
        type: ssid_mask
      - id: ctl
        type: u1

      - id: callsign_ror
        process: ror(1)
        size: 6
        type: callsign

      - id: callsign
        type: str
        encoding: ASCII
        size: 6

      - id: ssid_mask
        type: u1
        value: (ssid_mask & 0x0f) >> 1

      - id: pid
        type: u1
      - id: ax25_info
        size-eos: true

      - id: pid
        type: u1
      - id: payload
        size-eos: true

Then click on “Upload” and upload a binary file, i.e., downloaded form an observation’s data tab.

I’m sure we will, sooner or later, have a basic AX.25 parsing inside the data tab also.


Efficient format description. Here is the result of your lecture on one packet:


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Looks good! The suffix is encoded in ssid - 4X4HSL-1 for DUCHIFAT-3!

Keep in mind that you cannot display KISS encoded frames: they need to be “de-escaped” previously. I do have some small Python scripts for that. If there would be the need to
directly parse KISS frames, we would need to implement this functionality as kaitai-process. For the Web IDE this has to be done in JavaScript.

And what is the link with satnogs-dashboard? Where do you put Katai structs to get the decodings in the dashboard?

They are placed inside the package satnogs-decoders, find it here. There is an additional feature needed to export (only) the useful fields into the influxDB. These fields are then available, along with some tags like satnogs-decoders’ version, NORAD-ID etc, pp, in the grafana dashboard editor.

See README and feel free to ask any questions if you’re interested in building one. The structs are located inside the ksy/ folder.

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It looks like that the best match for TLE is OBJECT C (44854):

The TLE have been updated to network and now Duchifat-3 follows NORAD ID 44854.

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More recent observations confirm the NORAD ID 44854 for Duchifat-3

DUCHIFAT-3 is now identified as 44854.