[USRP-users] Tuning resolution of TwinRX + DDC?
p.boven at xs4all.nl
Fri Mar 22 09:39:29 EDT 2019
We recently did VLBI observations centered at 1332.49 MHz, using a X310
with TwinRX. The USRP was locked to external references for 10MHz and
PPS for this. To get the best phase noise, I used 'integer-N' tuning. We
noticed that overall, our receiver frequency was off by 0.118 Hz. This
causes the phase of the recorded signal to rotate in about 9 seconds,
compared to the other stations participating.
As far as I understand, when using integer-N tuning, the DDC simply
takes care of the remaining offset. What would be the tuning resolution
of the TwinRX itself (using int-N), and what is the resolution of the
DDC which corrects for this?
Regards, Paul Boven.
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