Soyuz-2.1b/Fregat - Ionosfera-M 3&4 - Vostochny - 25 July 2025 (05:54 UTC)

Ok, successfully reversed the LoRa parameters for the -4- 62.5k streams that I assume are the CSTP-4.x sats.

While just approximate, the freqs are:

436.734
437.162
437.246
437.326

#1, those freqs are ‘close’ - hopefully over time a more accurate center freq can be determined.

#2, I have no idea which sat goes with which freq… there was no ASCII in the payloads to identify the source.

For example, here’s one of the packets from 436.734 as I was replaying a packet to work out the parameters:

[22:58:47:734] Listening for downlink on 436.734 ......
[22:58:47:860] 
[22:58:47:860] BW=62.5    SF=8    CR=4/6
[22:58:47:860] Preamble_Len=6  SyncWord=0x12
[22:58:47:860] CRC=ON    LDRO=OFF    invertIQ=OFF
[22:58:47:967] -------------------------------------------------------
[22:58:49:035] 
[22:58:49:035] Reception Success!
[22:58:49:035] 
[22:58:49:035] Received 68 bytes:
[22:58:49:035] 
[22:58:49:035] 00 02 7E C0 3E B3 74 BA 83 68 C9 06 02 00 B0 0E 00 A8 FF F9 62 A2 00 00 62 A2 00 00 CE 20 80 00 12 40 07 00 14 00 05 01 11 00 01 76 46 32 48 F1 4C 01 01 01 00 08 08 00 00 00 08 00 3D 00 00 00 00 2C 00 00 
[22:58:49:286] 
[22:58:49:286] ..~.>.t..h..........b...b.... ...@.........vF2H.L...........=....,..

… always nice when there is some ASCII in a decode, but not this time.

I’ve notified the administrator of tinyGS.com so that he can add these 4 sats to that system. Collectively, the world-wide ground stations contributing to that database should be able to zero in on the exact frequencies and satellite ID’s of these downlinks.

As a bonus, there were a couple of 125k LoRa downlinks plus one 250k downlink. I’ll reverse those as soon as possible to see if they’re already known or something new.

5 Likes