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

[Cinaed Simson]

On 09/19/2016 05:46 AM, pen tester wrote:
> Hi Ron,
>   Thank you for that tx grc graph, it is super helpful! 
> 
>I am just trying to get a receive work now. I am using the 6_psk.grc
> from the tutorial folder in the github repo you were using [1].
> 
>   I have modified mine for using a hackrf on tx side and on rx side I
> modified to use the same sample rate and freq as your tx graph. I added
> a slider to help tune in to the freq, but I haven't had luck decoding
> yet - did you have a working rx graph you were using for testing?
> 
>   Thanks again! :-)
> 
> [1] https://github.com/argilo/sdr-examples/tree/master/tutorial

psk31.grc is BPSK and 6_psk.grc is QPSK.

You should put both the transit and receive in the same file without the
osmocom source and sink - connect the transmit and receive with a link -
cut out the hardware.

Then debug the encoding and decoding.

Otherwise, it may be hard to figure out if the problem is
encoding/decoding or timing, frequency or phase issues with the hardware.

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

[pen tester]

Hi Ron,
  Thank you for that tx grc graph, it is super helpful!

   I am just trying to get a receive work now. I am using the 6_psk.grc
from the tutorial folder in the github repo you were using [1].

  I have modified mine for using a hackrf on tx side and on rx side I
modified to use the same sample rate and freq as your tx graph. I added a
slider to help tune in to the freq, but I haven't had luck decoding yet -
did you have a working rx graph you were using for testing?

  Thanks again! :-)

[1] https://github.com/argilo/sdr-examples/tree/master/tutorial
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Re: [Discuss-gnuradio] PSK31 (from audio to radio)

[Ron Economos]

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/
 (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 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
 


 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 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. "..."
   * 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 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. 

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

[Cinaed Simson]

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/
>  (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  > 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
> 
> 
> 
> 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  > 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. "..."
>   * 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  > 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.
> 
> S

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

[pen tester]

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/ (examples/psk31_tx.grc)

On 10 September 2016 at 11:40, pen tester  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
>
>
> 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  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. "..."
>>- 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  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 
>>> 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.
>>

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

[Cinaed Simson]

On 09/09/2016 06:40 PM, pen tester 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 :-)

Looking at transmit.

It appears you start with something in memory so call the initial
pressure x - it will be likely be as fast as it can go.

Next is a resampler which bumps up the sampling rate to x*32.

Skipping the filter - which is a can of worms in itself - the next
resampler bumps up the sampling rate to x*32*48.

So before you get to the multiply, you appear to have some serious
plumbing problem.

Also, I wouldn't be calling math functions to calculate tap values on a
filter. I'd recommend calculation those taps by hand inserting the
values in the filter.

I recommend simplifying it by calculating the everything in front of the
first resampler and stick in a file - create a little back pressure.

And then I would move the FIR filter on the side of the resamplers which
you expect to have the highest sampling rate - which makes one of those
resamplers redundant.

Suppose you can suck in the contents of the file on the filesystem at a
sampling rate of 32k. Then you would need a resampler which decimates at
32k and interpolates at 48k - or interpolates at 3 and decimates at 2 -
to match 32k to 48k.

Now the osomo sink is sampling at 1.2 Hz.

My guess is the 1.2 Hz a mistake - you appear to have meant 1.2 MHz (or
1.2e6) in which case you need to interpolate at 25 and decimate at 1 to
match 48k to 1.2M.

Disclaimer: don't confuse me with someone who knows what they're talking
about - I'm just making this up as I go along. It's simply what I would
do to clean it - it may be wrong.


> 
> 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  > 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. "..."
>   * 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  > 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
> t

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

[pen tester]

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  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. "..."
>- 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  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 
>> 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
>>>
>>> Tur

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

[pen tester]

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. "..."
   - 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  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 
> 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 

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

[Tim K]

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  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 :-)
>
>
>
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>
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