hi i’m a college student in korea, I want to receive the CUAVA-2 signal, but when I convert PDU to stream and then to AX.25, the address doesn’t display correctly. I’m using a BladeRF SDR with Osmoscom. If you’re familiar with GNU Radio, could I get a sample flowchart, or could you help identify any issues in my GNU Radio flowchart
I think your best bet will be to ask in the gnu radio: general chat
when sharing, try to include the grc as well.
I like to reconstruct your problem. Could you provide me your .grc file and a sample file in .wav format?
Also, what do you mean by “the address doesn’t display correctly”?
Daniel
Also, what do you mean by “the address doesn’t display correctly”?
– I mean The hex data address field doesn’t match, meaning the address field—such as AC 96 64 AA A6 B2 for CUAVA-2—doesn’t align with my expected data. I think the HDLC deframer may have passed on incorrect data.
Thank you so much for helping me out. I’d appreciate it if you could check the parameters in my GRC file, and I don’t have a WAV format file available.
is correct, it’s shifted 1 bit to the left according to the AX.25 protocol.
If you shift it back 1 bit to the right, you will get an ASCII code where you can directly convert to VK2USY, CUAVA-2’s callsign.
I’m sorry for the misunderstanding, what I meant is that my data doesn’t come out like that.
Is there a criterion for determining the parameters of a low pass filter, symbol sync, and Costas loop? It’s because the signal doesn’t seem to be properly filtered.
Ah, sorry, got you now.
I tried to reconfigure your flowgraph to process .wav files, but had no success yesterday evening. Will have a look on it at a later time. Currently new satellites are in orbit catching my attention.
Oh Thank you so much for trying to help! I hope things will work out all right.
I also had no luck using your flowgraph.
However, switching to bpsk.grc from gr-satellites with minor modifications, I got my wav recordings correctly decoded.
Modified bpsk.grc and my wav recordings:
gr-bpsk+recordings.zip (1.4 MB)
Hope this helps you.
Daniel
Thank you so much for your help.
By the way, how can I apply your .wav recording file to your .grc file?
It’s my first time using Audio Source block. So please forgive me.
We’ve tried using Wav File Source → Audio Sink so that we can apply .wav file to Audio sink, which was not working.(1st pic)
AND also tried Wav File Source itself.(2nd pic)
This is my flow chart;
+) We are using bladeRF, so now we are working on using “osmocom source”, which can receive IQ file(complex type). If you know how to connect your flow chart with blade RF, please tell us.
Thanks so much for your help!!
Just use an audio player to play the wav file. The block Audio Source takes the sound card’s output as input. Make sure your audio out goes into gnuradio or both meets on “monitor” by checking the audio mixer of your system.
As for bladeRF I’m not a good help since I don’t have such a hardware.
Thank you! i’ll ask you one more question, why did you multiply the signal source?? and why did you use a multiply const block in the middle?? are there any criterion??
I took the bpsk.grc from gr-satellites and didn’t ask questions 
I don’t know why this is being done here.
Ah did you also get the wav file from there???
The wav file is from my own recording.
I’ve fully understood the demodulation flow chart you provided, but I think there might be an issue with how I’m receiving my signal. Could I refer to the flow chart you use when receiving a WAV file?
