Phase stability of 100MHz clock in USRP2

Dear All,

Please tell me the phase stability of 100MHz clock in USRP2 when the
100MHz clock is locked to an external 10MHz reference signal.

I have measured the temporal variation of phase difference between two
USRP2 outputs when a 10MHz signal is fed into PPS IN ports of two
USRP2s. The input signal of each USRP2 is fed by a same oscillator where
the output frequency is set to 26MHz. The result indicates the phase
difference varies from 0 to 2pi radians in about 100msec. This similar
result is obtained in the case a 10MHz signal is not fed into PPS IN
port. I think this observed temporal variation of phase difference is
too rapid, therefore, suspect the 100MHz clocks are unlocked to the
external 10MHz signal.

Best regards,
Nakajo T.

On 02/12/11 07:10 AM, Nakajo T. wrote:

result is obtained in the case a 10MHz signal is not fed into PPS IN
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

Are you configuring your UHD sink to use the extneral ref clock?

Does your external reference meet the hardware requirements:

http://files.ettus.com/uhd_docs/manual/html/usrp2.html#ref-clock-10mhz

Have you measured the phase noise of your reference?


Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

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