About the sampling rate

Dear all,

I find the sampling rate of USRP is surprisingly accurate.

Now I set the sampling rate as 4 MHz, and there are always exactly 4M
between two pps signals.

Even if I take off the GPS antenna, the sampling rate is still very

This means I only need the GPS antenna at the beginning to get an
time stamp.

Later I can take off the antenna and still can get accurate time from
sampling rate.

My colleagues and I do not understand how does USRP make the sampling
so accurate.

We had used other types of A/D converters before.

They usually do not have such accurate sampling rate.

Sometimes they have around 4M plus and minus 100 points in one second
4M sampling rate.

Thanks for your attention.


Well, we’re just that good, I guess.

The optional GPSDO used in the N210 has an extremely accurate
oven-controlled crystal oscillator inside to provide a frequency
with excellent holdover characteristics. The GPSDO drifts very little
the N210s frequency will remain accurate for some time after GPS signal


On Thu, Sep 27, 2012 at 1:45 AM, Ting Wu <