[Discuss-gnuradio] running ofdm benchmark on XCVR2450 vs RFX2400

[Apurv Bhartia]

Hey - 

This is a strange thing that I've been facing. We recently purchased new XCVR2450 daughterboards and wanted to test the ofdm benchmark code on it (with default settings). Both the USRPs (USRP1), were almost next to each other but yet, the receiver USRP does not show any packets being received. This is strange, since I plugged in a spectrum analyzer next to it, and it shows that the signal is indeed transmitted. I believe there's some issue with the rate at which the transmission takes place. I decreased the decimation rate to 4 on receiver and as expect it indicates overrun. However, when I increase it beyond 16, all I get are TIMEOUTs. 

At the sender, the interpolation rate is 128. I tried playing with some other values but couldn't get the reception to take place at the receiver. 

What is incredibly surprising is this - if I plug in the RFX2400 boards instead of these, they work with the default settings, except that I have to increase the tx-amplitude. I'm totally stumped at this behavior.  

The machines are not loaded at all, there's just the USRPs running (Ubuntu 9.04, 2.6GHz). I also checked the /proc/cpuinfo to verify, and it seems that the clock speed is fine.

I'd appreciate any help. I thought the changeover from RFX2400 to XCVR2450 would be smooth, but its giving me a bit of a nightmare. Btw, I'm running a stable 3.2.2 release of gnuradio. 

Thanks,
Apurv