On 09/10/2016 05:19 PM, pen tester wrote: > Thanks Cinaed for your response. > > For everything up to the multiply on the TX side - this is actually from > a working example that TXs using an audio card [1]. So just for a proof > of concept I would like to leave that as-is and just append on TX over > Osmocom Sink. Happy to look at simplifying later, just wanted to get POC > for PSK31 over radio for now on the transmit and receive. > > Also thanks for spotting my Freq mistake too. > > My plan now is to use the fldigi app for testing the rx side while I try > and make the rx side work - just figuring out how to write to a wav file > sink that is accepted by fldigi too... and trying to find some TX examples. > > [1] https://github.com/tkuester/gr-psk31/ > <https://github.com/tkuester/gr-psk31/> (examples/psk31_tx.grc) >
The output of the psk31_tx.grc example doesn't appear to be either BPSK or QPSK - both which should have a constant envelope - or at least approximately constant. Instead, the output looks like a beat signal of 2 signals close in frequency - resulting in an envelope varying in amplitude. I'm presuming psk31 implies BPSK with a low baud rate - 31 symbols per second. I may be missing something. > On 10 September 2016 at 11:40, pen tester <testerofp...@gmail.com > <mailto:testerofp...@gmail.com>> wrote: > > 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 > <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 > <http://pasteboard.co/1dLZWV9mv.png> > > > [1] https://github.com/tkuester/gr-psk31/ > <https://github.com/tkuester/gr-psk31/> (examples/psk31_tx.grc) > [2] https://github.com/tkuester/gr-psk31/ > <https://github.com/tkuester/gr-psk31/> (examples/psk31_rx.grc) > [3] https://www.csun.edu/~skatz/katzpage/sdr_project/sdr/grc_tutorial3.pdf > > <https://www.csun.edu/%7Eskatz/katzpage/sdr_project/sdr/grc_tutorial3.pdf> > > On 6 September 2016 at 05:49, pen tester <testerofp...@gmail.com > <mailto: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 > <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 > <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/ > <https://github.com/tkuester/gr-psk31/> (examples/psk31_tx.grc) > [2] https://github.com/argilo/sdr-examples > <https://github.com/argilo/sdr-examples> (tutorial/6_psk.grc) > [3] https://github.com/tkuester/gr-psk31/ > <https://github.com/tkuester/gr-psk31/> (examples/psk31_rx.grc) > > On 4 September 2016 at 12:33, Tim K <tpkues...@gmail.com > <mailto: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 <mailto: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/ > <https://github.com/tkuester/gr-psk31/> > (examples/psk31_tx.grc) > Receive: https://github.com/tkuester/gr-psk31/ > <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 > <http://www.megafileupload.com/7sm9/psk31_tx.grc> > Transmit Image: http://pasteboard.co/giNm3kNzC.png > <http://pasteboard.co/giNm3kNzC.png> or > http://www.megafileupload.com/7smc/psk31_tx-audiocard.png > <http://www.megafileupload.com/7smc/psk31_tx-audiocard.png> > > Receive Graph: > http://www.megafileupload.com/7sma/psk31_rx.grc > <http://www.megafileupload.com/7sma/psk31_rx.grc> > Receive Image: http://pasteboard.co/giOlxtWUf.png > <http://pasteboard.co/giOlxtWUf.png> or > http://www.megafileupload.com/7smb/psk31_rx-audiocard.png > <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 > <https://github.com/argilo/sdr-examples> (multi_tx.grc) > Receive: https://github.com/argilo/sdr-examples > <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 > <http://www.megafileupload.com/7smi/psk31_tx-attempt2.grc> > Transmit Image: http://pasteboard.co/giOMGNqD9.png > <http://pasteboard.co/giOMGNqD9.png> or > http://www.megafileupload.com/7sme/psk31_tx-attempt2.png > <http://www.megafileupload.com/7sme/psk31_tx-attempt2.png> > > Receive Graph: > http://www.megafileupload.com/7smh/6_psk-hackrf.grc > <http://www.megafileupload.com/7smh/6_psk-hackrf.grc> > Receive Image: http://pasteboard.co/giPflR4TI.png > <http://pasteboard.co/giPflR4TI.png> or > http://www.megafileupload.com/7smf/6_psk_hackrf.png > <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/ > <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 <mailto:Discuss-gnuradio@gnu.org> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio> > > > > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
