Re: [Discuss-gnuradio] OFDM Benchmark Tx Issue?

[Michael Dickens]

On Feb 21, 2012, at 9:44 AM, Tom Rondeau wrote:
> It's because with the larger bandwidth, the subcarriers, too, have a larger 
> bandwidth. The coarse frequency correction is only set to look at so large an 
> offset based on a number of subcarriers (+/-5 or 10), so now with the same 
> frequency offset, 5 (or 10) carriers is a larger frequency span to check.

Ah; yes.  That makes sense.  My mind is thrashing with multi-thread dilemmas, 
not signal processing, right now.

>> 1 MHz off at 5 GHz is 200 ppm (yes?).  IIRC a reasonable spec on these 
>> boards is 5-10 ppm.   So, > 10x off the spec?  I doubt it.  My guess is it's 
>> something in GNU Radio that wasn't fixed when the benchmarks were 
>> transitioned from gr-usrp* to UHD.
> 
> I think this is a known problem with the XCVR that has been fixed. Make sure 
> you have the most up-to-date master branch of both the UHD and GNU Radio.

They were both the most recent as of yesterday.  I'll update right now & see if 
that helps, but I'm doubtful since none of the commits since yesterday seem to 
impact the behavior of the XCVR.  I'll also remove any cruft in /usr/local 
before re-installing.  More later. - MLD