Creating the parser for a new satellite downlink

SatNOGS
1

Hello everyone, :blush:

I am new to this platform, and have just started learning the processes and how to contribute.
I encountered the process of creating a parser for a new satellite downlink and started reading through the steps. However, as I am new, I might have some confusions while I learn. So my first question is in the steps it says “Find and read documentation of the satellite downlink”. In the documentation tab of the site, I did not find any related to this. Could you please help me understand what I have to do for this?

Best Regards

2

Hi!

If you want to develop a praser for a new satellite you will need exact information on how the data is stored within the PDUs. Normally, you will get a HEX-string out of an observation, which is the starting point for you:
53 4F 4E 30 33 41 54 7F 89 68 7F 00 00 00 00 3A C5 7F 06 7F 80 7F 00 00 7F 85 84 7E 05 7F 80 82 07 49 48 C0 02 8F 0F 00 3A 00 0A 21 2D 1E B7 74 7E 6A 93 A2 9E F2 F1 9C 40 BC AD 92 08 59 C9 47

Now you have to know, how each byte is formatted. This information should be publicly available for ham-radio satellites. E.g. for our PEGASUS satellite you will find it here.

From this documentation you will find following information for the first 8 bytes of the above PDU:

image
image919×604 93.8 KB

Byte 0: 53 → Format: HEX → 53 (OBC-Beacon 1)
Byte 1-6: 4F4E30334154 → Format: ASCII → ON03AT (CALL-Sign)
Byte 7: 7F → Format: UFix 3.5 → 3.969 V (V_PV1)
Byte 8: 89 → Format: UFix 3.5 → 4.281 V (V_PV2)
…

Getting the readable telemetry data out of a HEX-string is what a parser does. Your first step is to find out how to convert the bytes as shown above. :slight_smile:

I have it on my to-do list to add a parser for our PEGASUS satellite, but I am too busy for it currently.

A short example on how to develop a parser is shown in the following guide on YoutTube:

Cheers,
Alex, OE3ALA

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