Re: [Discuss-gnuradio] Doubt with file sink with ofdm and CC

Hi Marcus!

Thank you for you reply!

So I am trying to make a OFDM system with and without codification (CC code)... for this I am using these flowgraphs (simpleOFDM.png and CodeOFDM.png)

The problem that I saw is: If I use just codification without modulation (just to try), the output scope is the same as the input (in this case, I am using a square waveform).

And when I use just OFDM modulation, the output signal looks stay with a time delay and also looks not be constant during the whole simulation (see pics OFDMscope and OFDM2.png).

And when I use CC code + OFDM, I also have a delayed time signal and sometimes with a lot of wrong peaks but I don't insert on the simulation any noise signal or use some USRP to transmit and receive through the air. (see pics OFDM+CC_1 and OFDM+CC_2.png).

after it, I am trying to transmit a CSV or TXT file with both situation (just OFDM and OFDM+CC code) to compare the results... but as I can check for now, the situation with OFDM+CC code get a lot of wrong information as without code... It should be the other way, isn't it?

I hope I made it clear

Thanks!

José

2016-05-25 10:01 GMT-03:00 Marcus Müller-3 [via GnuRadio] <[hidden email]>:

Hi Jose,

could you explain the problem a bit more in-depth? I'm afraid I'm not
really understanding.

By the way, if you sign up to the mailing list directly [1], you could
directly attach the "saved to image file" (file->screen capture in GRC)
output so that we can understand what you're doing.

This time delay, why is it a problem? Is it a multiple of the number of
symbols per OFDM symbol?

Best regards,
Marcus

[1] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
On 25.05.2016 14:48, Jose Perez wrote:

> Well, I resolved the second point... just put a Unpack K Bits after the File
> Source block and then a Pack K Bits block before the File Sink block.
>
>
> Someone could help me in the first question? The file that I received get a
> lot of wrong information with just virtual transmittion... there is no noise
> to justify this problem.
>
> Thank you again.
>
>
>
> --
> View this message in context: http://gnuradio.4.n7.nabble.com/Doubt-with-file-sink-with-ofdm-and-CC-tp60156p60178.html
> Sent from the GnuRadio mailing list archive at Nabble.com.
>
> _______________________________________________
> Discuss-gnuradio mailing list
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.: José Perez Jr

From:	Jose Perez
Subject:	Re: [Discuss-gnuradio] Doubt with file sink with ofdm and CC
Date:	Wed, 25 May 2016 07:14:08 -0700 (MST)