Re: [Discuss-gnuradio] USRP2 phase drift

[Matt Ettus]

On 07/26/2010 11:22 AM, senlin peng wrote:
> I still get phase drift even with atomic external clock connected and
> configured in software with config_mimo(MC_WE_LOCK_TO_SMA).
>
> I tried with GPS signals and a sinusoid from the function generator as
> the inputs. There is phase drift in both cases. The attachment shows a
> picture of the phase error fluctuation. Does this problem cause by the
> 100 MHz main oscillator on the main board?


Even if you lock the USRP2 to an external reference, there will still be 
drift relative to other things not connected to the same reference.  The 
function generator has its own clock, as does GPS.

Matt