I have an alternative flow graph. It's based on the multi_tx.grc flow
graph in https://github.com/argilo/sdr-examples. The osmocom Sink is set
up for a bladeRF, so be sure to change that for hackRF. The message in
the Vector Source block in "This is W6RZ testing." with a trailing line
feed.
http://www.w6rz.net/psk31.grc
Ron
On 09/13/2016 11:11 PM, Cinaed Simson wrote:
> 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 <testerofpens@gmail.com
>> <mailto:testerofpens@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 <testerofpens@gmail.com
>> <mailto:testerofpens@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 <tpkuester@gmail.com
>> <mailto:tpkuester@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
>> <testerofpens@gmail.com <mailto:testerofpens@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 :-)
>>
>>
>>
>> _______________________________________________
>>
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