Tim, Yes, your graphs are really useful :-) Thank you for responding in such detail!
Here is what I am up to: Transmit side: - I made your changes to your transmit graph [1] - All the changes were fine but I was confused about the use of the Polyphase Resampler as I could not get the values to work without underflows when executing i.e. "UUUU..." - So instead (this is probably wrong) I tried using a Rational Resampler with an Interpolation of 1e6 and a Decimation of 48e3. - Updated version: http://pasteboard.co/hmyGOGTE4.png - Either way, the tx graph looks healthier - just need some advice on the resampler perhaps? Receive side: - I am using the start of this receive graph [2] as it was using radio rx already - and just modifying the demod portion to be more like your rx graph - Updated version: http://pasteboard.co/hmzrMBAIi.png - I also need advice from anyone who could point in the right direction on the AM rx side please? [1] https://github.com/tkuester/gr-psk31/ (examples/psk31_tx.grc) [2] https://github.com/argilo/sdr-examples (tutorial/6_psk.grc) [3] https://github.com/tkuester/gr-psk31/ (examples/psk31_rx.grc) On 4 September 2016 at 12:33, Tim K <[email protected]> wrote: > Hey hey! > > Glad to see someone using this. (And that it's apparently still working! > Goodness... I need to clean this up...) > > I'm giving advice freehand right now, as I don't have my radios with me to > test this. There are definitely more elegant ways for this solution, this > is just the quickest I could think of without reverse engineering what I > wrote forever ago. > > Since this is AM, I think you'll only need the Real port on your "Float to > Complex" block. You can attach the "Null Source" to the Imaginary port. Do > a quick check to make sure the real signal's not exceeding +/- 1... you > might want to attenuate it to +/- 0.7 for now, someone else should comment. > > As far as the transmit side goes, I'd leave everything up to the > "Multiply" block untouched. Consider that your "audio input" to the radio. > After that... > - Multiply Const (set to 0.7 for safety) > - Polyphase Resampler (float/float) set to (1e6 / 48e3) - This gets your > sample rate up to radio speeds > - Float to Complex (in the Real port, Null Source to the Imag port) - > This makes your signal "complex AM" > - Send the Complex stream into your Osmocom Sink (set to 1e6 sps) - And > transmit! > > If I remember correctly, some radios don't like working at non-integer > sample rates. (The hackRF may be ok though...) > > Play gently with your TX gain until you can see it on another radio. (IIRC > the HackRF is simplex... perhaps an RTL?) Use AM to demodulate. > > I've been meaning to do a write up on this for a while. If I ever get > around to it, I'll make sure to CC you. > > - Tim > > > On Fri, Sep 2, 2016 at 11:55 PM, pen tester <[email protected]> > wrote: > >> 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 >> ========================================== >> 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 >> ========================================================== >> 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 >> ================= >> 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 >> ============ >> 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 :-) >> >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> [email protected] >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >
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