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

Satellites & Observations Launches
1

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.

2

We probably have caught it and demodulate it in several observation like:
https://network.satnogs.org/observations/1356566/

3 Likes
3

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

4

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!

5

Is there an easy way to see 4X4HSL and GS you speak about in the hex or ASCII of https://network.satnogs.org/observations/1356566/#tab-data ?

6

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

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7

Duchifat-3 changed in network to follow 44853 object.

8

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:

---
meta:
  id: ax25header
  endian: le

seq:
  - id: ax25_frame
    type: ax25_frame
    doc-ref: 'https://www.tapr.org/pub_ax25.html'

types:
  ax25_frame:
    seq:
      - id: ax25_header
        type: ax25_header
      - id: payload
        type:
          switch-on: ax25_header.ctl & 0x13
          cases:
            0x03: ui_frame
            0x13: ui_frame
            0x00: i_frame
            0x02: i_frame
            0x10: i_frame
            0x12: i_frame
            # 0x11: s_frame

  ax25_header:
    seq:
      - 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

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

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

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

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

  ui_frame:
    seq:
      - 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.

2 Likes
9

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

idekatai

1 Like
10

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

11

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.

12

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

13

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.

1 Like
14

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

305972727778_B
305972727778_B823×1606 684 KB
307720412963_B
307720412963_B832×1606 682 KB

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

1 Like
15

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

16

DUCHIFAT-3 is now identified as 44854.

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