Re: [Discuss-gnuradio] BER & SNR (was: Re: (no subject))

[Rafik ZITOUNI]

Marcus,

You find attached my flow graph with  Tx and Rx. I know that it is not
recommended to have TX and RX in the same flow graph but i did it just to
obtain one view for my Tx and Rx.

Thanks,

2017-07-04 11:23 GMT+02:00 Marcus Müller :

> Dear Rafik,
>
> I think we're approaching this from the wrong side: I don't think that I
> should be explaining why you get a good BER and SNR estimate, it is you who
> should explain why you're expecting something different, and then we can
> discuss! I'm not quite sure what I could be explaining at this point :)
>
> Best regards,
>
> Marcus
>
> On 07/04/2017 11:20 AM, Rafik ZITOUNI wrote:
>
> Thank you Marcus for your answer !
>
> My BER and SNR are calculated and obtained using MPSK SNR Estimator Probe
> and Error Rate blocks. I obtained  two points, which rotate in the qt gui
> constellation sink despite the BER and SNR have been obtained as expected.
> Could you give me an explanation how it was possible to obtain a good snr
> and ber with a wrong constellation with  good SNR and BER?
>
> I found the  presentation of Tom Rondeau useful, since he explained the
> function of the costas loop block.  https://static.squares
> pace.com/static/543ae9afe4b0c3b808d72acd/543aee1fe4b09162d08
> 633fc/543aee1fe4b09162d0863402/1392309732018/mpsk.pdf
>
>
> This morning I add a Costas loop after a Polyphase Clock Syncronisation
> block, and it s going well. You find attached a screenshot of my
> constellation for a DBPSK of my receiver/transmitter. I propose to add a
> grc to gnuradio/gr-digital for MPSK since grc is more easy to understand
> than python source code.
>
>
> Now I am trying to send and receive data files such as videos or images
> (bmp). Do you have an example with a file exchange implemented in .py or
> grc?
>
> Best,
>
>
> 2017-07-04 9:44 GMT+02:00 Marcus Müller :
>
>> Hi Rafik!
>>
>> So, what's wrong with the BER and the SNR estimate?
>>
>> Best regards,
>>
>> Marcus
>>
>> On 07/03/2017 11:29 PM, Rafik ZITOUNI wrote:
>>
>> Dear all,
>>
>> I translate the /gr-digital/examples/narrowband/digital_bert_tx.py and
>> the /gr-digital/examples/narrowband/digital_bert_rx.py python source
>> codes to GRC flow graphs. The objective is to get more graphical
>> possibilities with a GRC.  My flow graph gives a fine result of BER and SNR
>> for DBPSK modulation.
>> The problem is with the rotating points of my constellation. I think that
>> the rotation of my view comes from a lack of frequency synchronization, but
>> why I obtained a correct BER and SNR?
>>
>> You find attached to this message a constellation view obtained by my
>> flow graph.
>>
>> Please could you explain me this  result or give an advice to improve the
>> obtained result?
>>
>> Regards,
>>
>>
>> --
>> Rafik
>>
>>
>>
>> ___
>> Discuss-gnuradio mailing 
>> listDiscuss-gnuradio@gnu.orghttps://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>
>> ___ Discuss-gnuradio mailing
>> list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/
>> listinfo/discuss-gnuradio
>
> --
> Rafik
>
>


-- 
Rafik
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[Discuss-gnuradio] BER & SNR (was: Re: (no subject))

[Marcus Müller]

Dear Rafik,

I think we're approaching this from the wrong side: I don't think that I
should be explaining why you get a good BER and SNR estimate, it is you
who should explain why you're expecting something different, and then we
can discuss! I'm not quite sure what I could be explaining at this point :)

Best regards,

Marcus


On 07/04/2017 11:20 AM, Rafik ZITOUNI wrote:
> Thank you Marcus for your answer !
>
> My BER and SNR are calculated and obtained using MPSK SNR Estimator
> Probe and Error Rate blocks. I obtained  two points, which rotate in
> the qt gui constellation sink despite the BER and SNR have been
> obtained as expected. Could you give me an explanation how it was
> possible to obtain a good snr and ber with a wrong constellation with
>  good SNR and BER?
>
> I found the  presentation of Tom Rondeau useful, since he explained
> the function of the costas loop
> block.  
> https://static.squarespace.com/static/543ae9afe4b0c3b808d72acd/543aee1fe4b09162d08633fc/543aee1fe4b09162d0863402/1392309732018/mpsk.pdf
> 
>
>
> This morning I add a Costas loop after a Polyphase Clock
> Syncronisation block, and it s going well. You find attached a
> screenshot of my constellation for a DBPSK of
> my receiver/transmitter. I propose to add a grc to gnuradio/gr-digital
> for MPSK since grc is more easy to understand than python source code.
>
>
> Now I am trying to send and receive data files such as videos or
> images (bmp). Do you have an example with a file exchange implemented
> in .py or grc?
>
> Best,  
>
>
> 2017-07-04 9:44 GMT+02:00 Marcus Müller  >:
>
> Hi Rafik!
>
> So, what's wrong with the BER and the SNR estimate?
>
> Best regards,
>
> Marcus
>
>
> On 07/03/2017 11:29 PM, Rafik ZITOUNI wrote:
>> Dear all, 
>>
>> I translate the
>> /gr-digital/examples/narrowband/digital_bert_tx.py and the
>> /gr-digital/examples/narrowband/digital_bert_rx.py python source
>> codes to GRC flow graphs. The objective is to get more graphical
>> possibilities with a GRC.  My flow graph gives a fine result of
>> BER and SNR for DBPSK modulation. 
>> The problem is with the rotating points of my constellation. I
>> think that the rotation of my view comes from a lack of frequency
>> synchronization, but why I obtained a correct BER and SNR?
>>
>> You find attached to this message a constellation view obtained
>> by my flow graph. 
>>
>> Please could you explain me this  result or give an advice to
>> improve the obtained result? 
>>
>> Regards, 
>>
>>
>> -- 
>> **Rafik
>>
>>
>>
>> ___
>> 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
>  
>
> -- 
> **Rafik
___
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