Hi, Still playing around and I have a question about the value which should go in the Polyphase Resampler on the tx side please. Any advice on the AM rx too would be helpful :-)
Transmit - Simply trying make the working PSK31 audio tx to tx over HackRF instead using [1] and updates from Tim's response - Screenshot: http://pasteboard.co/1dLjHxMAU.png Receive - Simply trying to make the working PSK31 audio rx work using a RTLSDR instead based on [2] - The first line is an attempt to take in the AM signal and just pass it on to [2] - For the AM rx, I used [3] as a guide - Screenshot: http://pasteboard.co/1dLZWV9mv.png [1] https://github.com/tkuester/gr-psk31/ (examples/psk31_tx.grc) [2] https://github.com/tkuester/gr-psk31/ (examples/psk31_rx.grc) [3] https://www.csun.edu/~skatz/katzpage/sdr_project/sdr/grc_tutorial3.pdf On 6 September 2016 at 05:49, pen tester <testerofp...@gmail.com> wrote: > 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 <tpkues...@gmail.com> 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 <testerofp...@gmail.com> >> 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 >>> Discuss-gnuradio@gnu.org >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >>> >> >
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