Using 10 MHz gps disciplined clock for USRP external clock

GNU Radio
1

Hi all,

I will be interested if anyone tried to use 10 MHz gps disciplined clock
outputs on USRP as an external clock.
I believe USRP will not be doing good at 10 MHz clock so what will be
the
best way to use this output from GPS with USRP…
Thanks in advance

-Burak

2

On Thu, 2010-12-23 at 04:18 -0500, Burak TUYSUZ wrote:

Hi all,

I will be interested if anyone tried to use 10 MHz gps disciplined
clock outputs on USRP as an external clock.
I believe USRP will not be doing good at 10 MHz clock so what will be
the best way to use this output from GPS with USRP…
Thanks in advance

USRP2 has an SMA connector on the front which will take a 10MHz
reference to synchronize the oscillator. USRP1 does not. This is not
readily doable on a USRP1 as it doesn’t use a VCO, it uses a fixed 64MHz
oscillator.

That said, I have done this on my USRP1. I modified the USRP to use an
external clock and built a 64MHz reference oscillator using a GPSDO and
a homemade PLL, using an Si570 as the VCXO. It works pretty well,
although when I finally put it on a phase noise analyzer it didn’t look
particularly great.

In hindsight, it might be easier to solve the frequency mismatch problem
in software. =)

–n