[Discuss-gnuradio] PSK31 (from audio to radio)

[pen tester]

Hi,

I am trying to get a simple working example of PSk31 working (transmitting with a hackrf and receiving with a rtlsdr dongle). Here is what I have so far.

Working PSK31 tx and rx with a sound card

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Transmit: https://github.com/tkuester/gr-psk31/ (examples/psk31_tx.grc)

Receive: https://github.com/tkuester/gr-psk31/ (examples/psk31_rx.grc)

These work great for sending a PSK31 message over audio card and receiving with the audio card.

I just slightly modified them to take input from the "Audio Source" block instead of a "Wav File Source" to use the sound card directly:

Transmit Graph: http://www.megafileupload.com/7sm9/psk31_tx.grc 

Transmit Image: http://pasteboard.co/giNm3kNzC.png or http://www.megafileupload.com/7smc/psk31_tx-audiocard.png

Receive Graph: http://www.megafileupload.com/7sma/psk31_rx.grc

Receive Image: http://pasteboard.co/giOlxtWUf.png or http://www.megafileupload.com/7smb/psk31_rx-audiocard.png

Turning up the audio a little and tuning to 2003 approx on the rx graph results in reception of the sent message "Hello World!"

Reference version for using hackrf instead of sound card

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Next, I wanted to modify these to audio versions to work over Radio using a HackRF and RTLSDR dongle.

These graphs seems very useful but I couldn't get it working end to end for some reason.

Transmit: https://github.com/argilo/sdr-examples (multi_tx.grc)

Receive:  https://github.com/argilo/sdr-examples (tutorial/6_psk.grc)

I made some changes to the freq to be in range for RTLSDR .e.g changed freq from 441e6 in ref graph, changed to 841e6. 

My merged attempt

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The attempt I am currently trying to get working is based on the audio soundcard flies for the transmit:

Transmit: Using  audio tx (psk31_tx_attempt2): where I just replaced the audio sink with the Osmocom sink (not sure what else is needed here for transmission over hackrf)

Transmit Graph: http://www.megafileupload.com/7smi/psk31_tx-attempt2.grc

Transmit Image: http://pasteboard.co/giOMGNqD9.png or http://www.megafileupload.com/7sme/psk31_tx-attempt2.png

Receive Graph: http://www.megafileupload.com/7smh/6_psk-hackrf.grc

Receive Image: http://pasteboard.co/giPflR4TI.png or http://www.megafileupload.com/7smf/6_psk_hackrf.png

For the receive, I just left radio rx part in and replaced the decoder parts with decoding logic from https://github.com/tkuester/gr-psk31/ (examples/psk31_rx.grc). I made other minor changes such as freq and sample rates.

My question

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So in summary, just looking for a little guidance on my merged attempt to get psk31 out over a hackrf and received using a RTLSDR. Any advice for a learner would be great :-)