I play the ogg file back using audacity (either save as a wav and load into FoxTelem or pipe through a virtual cable or loopback). In FoxTelem I treat it as an IQ File at 48k. It shows the spectrum mirrored around zero Hz because it is really an audio file. I set the Decode point to +12kHz and it decodes.
The Dot Product BPSK decoder (designed by KA9Q) works best and is the default in FoxTelem. It works better than the Costas loop decoder.
Is it possible to do with gr-satellites ? I started a discussion over there. Wanting to be able to demodulate this live and automatically, no gui/windows/manual work.
Iβve been working on this for a couple of hours since the tip was posted (Thank You!) about feeding SatNogs audio to a BPSK demodulator as if it were an I/Q file, but no luck yet.
Of course Iβll speak up if I find the correct settings!
-Scott
To be specific, Iβm talking about IQ data here, as this is what is coming out of the flowgraphs over udp, also what I use to experiment with demodulation.
The audio is a possible post processing route, but not what I am working on.
@SA2KNG There is no reason this canβt work in gr-satellites. There is nothing special about the bpsk decoder. I tried many designs and Phil Karns worked best. He has a C reference implementation and I ported it to Java.
On the Gui/windows question. You can run foxtelem on Linux. I develop it on Ubuntu and it can run from the command line with switches for a specific decoder.
Ok, looks like I can stop trying to twist this into working w/ any of the existing gr-satellites deframersβ¦ Dani replied to the question posted in the gr-satellites repository and indicated that heβd have to look into a custom deframer for this sat.
It seems there is a great chance that CatSat is finally deployed!!!
For now we are using this TLE set for tracking it at 437.185 MHz (thx @PE0SAT):
CATSAT
1 99164U 24198.27847222 .00000000 00000-0 49625-3 0 09
2 99164 97.3214 52.1281 0021945 218.7436 152.7891 15.18790192 04
Any demodulated frames are more than welcome!
More updates and final confirmation will follow!
From #satnogs matrix channel, the power of the satellite is in critical state and it may tumbling a lot, this means that the satellite may not transmit all the time.
First observations of CatSat signals were around 2024-07-15 20:00 received by:
Given that we followed the rocket body of Firefly rocket for tracking and the slight deviation of the signal on the waterfall, there is a very rough estimation that the satellite was deployed recently (from a couple of hours to at most 2 days), however this is a rough estimation and need investigation for more accurate results.
what is the modulation type, could not find any information on their website
Just to add that currently the active is the 2k4 transmission.
For all the Windows users, use the 1KUNS-PF modem from UZ7HO.
This modem is part of the other-versions zip file
An updated TLE set for CatSat based on latest observations in Network and the initial TLE set calculated by @PE0SAT:
CatSat
1 99164U 24198.51307870 .00000000 00000-0 -49598-2 0 05
2 99164 97.3214 52.3271 0030009 217.6815 356.5707 15.19049090 00
catsat_198_v6.dat (2.6 KB)
sites.txt (7.1 KB)
The TLE above is not precise but accurate enough for good tracking of the satellite. More updates will follow.
No Signals heard during 13:43 UTC pass. Satellite was in Eclipse
No signals heard 15:15 UTC. CatSat was in eclipse.
Make sure to use the TLE shared in this post.
