Re: [Discuss-gnuradio] HELP! Is it a defective USRP1?

[Marcus D. Leech]

On 11/09/2010 05:34 PM, Rachel Li wrote:
> Hi All:
>
> I am experiencing something strange with USRP1 and already tried a lot
> of approaches to diagnose where the problem is, but no luck so far.
>
> We have two USRP1, each of which has a RXF 2400 daughter board and an
> antenna connected to the Tx/Rx port. When we run benchmark
> (benchmark_tx.py and benchmark_rx.py), the packet loss/corrupted rate
> is very random (from 0% to 99%).
>
> We've tried several approaches to diagnose where the problem, including
> (1) connect the Tx/Rx ports of two USRP by a SMA connector
> (2) try both sides of the mother board (A and B) ,
> (3) use different central frequency from 2.4G to 2.48G,
> (4) adjust the carrier threshold (20 to 50), tx amplitude (0 to 1) and
> rx gain (0 to 90),
> (5) place the radios in different locations,
> (6) use different versions of gnuradio (stable release version 3.3.0
> as well as the latest repository code)
> (7) place a fft sink at the rx to observe the spectrum, I can see the
> signal spectrum showing up when tx is transmitting something.
>
> Unfortunately, nothing really helps.
>
> Is it possible that it is a defective USRP?
>
> I really appreciate if anyone of you could guide me with this problem
> because I have a deadline to make in around 2.5 weeks.
>
> Thanks very much!
>
> Rachel
>   
My suggestion is that you use a more basic diagnostic.  Do both USRPs
have roughly the same
  sensitivity and output power?

If you transmit on one, and receive on the other with a FFT, with an
attenuator between them,
  can the Rx side "see" the other side, use increasing levels of
attenuation until the Rx can't
  see the transmitted signal anymore.




-- 
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org