Re: [Discuss-gnuradio] PSK Real Time Voice Tx/Rx

[Marcus D. Leech]

On 01/13/2014 04:38 PM, Marqo Torres wrote:

Hi, thanks for replying. I'm using 16kHz in Audio sample-rate and 256kHz in USRP sink/source blocks. 

Also I've noticed that when I change the config.d values in the files from the gnuradio folder there's a variation in the breaking up voice in the receiver's side.

In the transmitter's side I get "UUUUU" constantly and in the receiver's side i get "UaUaUaUa"  I know that it means Underrun and Audio Underrun, but I still don't have any idea of what I'm doing wrong.  

I've attached the flowgraphs of the Tx and Rx models. 

Regards 

Marqo.

Those UUUUU mean that your graph isn't able to to keep up with the notional sample-rate, either because of computational sluggishness, or because you aren't resampling appropriately within your flow-graph so that the hardware is receiving samples at the correct rate.

2014/1/13 Marcus Leech <address@hidden>

Indeed, don't use a throttle block for anything other than a simulation not involving hardware.

What sample-rate are you using, and are you getting overrun or underrun indications ('O' or 'U' printed).

 

 

on Jan 13, 2014, Marqo Torres <address@hidden> wrote:

Hello, I am working on a real time voice Tx/Rx using GNU Radio as software and a USRP E110. I'm trying to do a QPSK Modulation and I have consulted several models and forums and it seems everything is okay, however at the moment of receiving signal, the audio on the receiver is breaking up, and I want the audio sounds good. I thought it might be because of some errors in synchronism and carrier recovery, so I added the block MPSK Reciever, without any changes in the audio output. Is anything I am missing? or Is any calculation or number wrong? 

 

Could it be because of lack in processing? because I've tried the same model with GMSK mod/demod blocks and the voice sounds good. I've attached the flowgraphs of the Tx and Rx side for a better understanding.

 

I really appreciate your help and I look forward your reply.

Regards.

Marqo

 

P.S. I've also read that at the moment of involving blocks that work with hardware (USRP Sink/Source) I have to skip the Throttle blocks, is that true? 

 

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Marcus Leech
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Shirleys Bay Radio Astronomy Consortium
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