[USRP-users] Master Clock Supression
marcus.mueller at ettus.com
Fri Jul 17 11:19:14 EDT 2015
Shielding/separation-wise, the X310 should be pretty much superior in
every aspect -- not only is the ADC, DAC, mixer, amplifier and LO
synthesizers in one package on the B2x0 (the AD9361); the X310 is
modular in the sense that the MCR doesn't even appear to the
daugtherboards, necessarily; it's an FPGA-only clock, generated by the
clock distribution IC on the mainboard, and the UBX, especially to
suppress strong interferers, has a metal can (which is unique among our
RF hardware, so far). Under that metal can, there's a lot of partitions,
which align with the different jobs and frequency ranges on the board,
compare the schematic .
So since you're seeing 200MHz-harmonics, these might either spuriously
get into the antenna ports, or for some reason, at multiples of 200MHz
LO leakage is worse (I don't expect that). Have you tried using offset
tuning  to reduce these spurs?
On 17.07.2015 17:03, devin kelly via USRP-users wrote:
> I have an X310 with a UBX daughtercard. I've noticed that there are
> tones every 200 MHz (I checked 2.4GHx, 2.6 GHz, 2.8 GHz, 3 GHz, 3.2
> GHz). Do I have any options for suppressing the tones? Is there any
> shielding or RF absorber I can add somewhere?
> The B210s seem to have each section of radio gated off (to make it
> easier to add shielding?). But the X310s don't as far as I can tell.
> Thanks for any help,
> USRP-users mailing list
> USRP-users at lists.ettus.com
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