Re: [Discuss-gnuradio] Problem of benchmark_ofdm_rx.py. Could not receive.

Milo Wong wrote:
> Hi,
>
> I was doing a test using benchmark_ofdm_tx and rx to achieve the ofdm 
> communication between two USRPs. At first, both USRPs could transmit 
> and receive correctly. However, after swithing tx/rx part for a few 
> times, one USRP suddenly failed in receiving (still can transmit), no 
> matter which host PC it connected to. While, the other one still could 
> work both in tx and rx. The one could not receive sometimes had "TIME 
> OUT" after I stopped transmitting on the other side, or sometimes it 
> only displayed a received wrong package with a very big packge number, 
> or sometimes it had nothing to display.
>
> We tried to switched two daughter boards and the problem was the same, 
> still that one could not receive. Here are our test information:

I'm not exactly sure what you mean by "switching tx/rx part." Are you 
switching which roles the USRPs play?

From what you say below, you're running the RFX2400 board. This has 
caused problems in the past if the oscillator frequency was too far off. 
When you multiply this up to 2.4 GHz, it can cause two USRPs that are 
nominally at 2.45 GHz to be off by a few kHz. This can be enough to 
cause the USRPs to be out of frequency locking range. The oscillator 
will also drift with temperature. Since they were working for you 
originally, it might be that as they warmed up, they were pushed just 
far enough outside the frequency range to become a problem.

Given the information you've provided, that's the best answer I have 
right now. Do you have any other daughterboards you can test with? Can 
you run other examples that still work?

The "TIME OUT" message comes from the receiver when it correlates to the 
access code but isn't able to get the packets. So it's seeming 
something, just not well enough to fully receive.

Tom

> *Ubuntu 9.04
> gnuradio-3.2.2/gnuradio-examples/python/ofdm/benchmark_ofdm_tx & rx
> USRP/RFX2400*
>
> run command:
>
> *sudo python benchmark_ofdm_tx.py -f 2.45G
> sudo python benchmark_ofdm_rx.py -f 2.45G*
>
> Is there anyone who can help me with this problem? Thanks in advance!
>
>
> Sincerely,
>
> Yuan
>
>  
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