[USRP-users] Master Clock Supression
dwwkelly at gmail.com
Fri Jul 17 15:04:54 EDT 2015
Right now I've got two X310s each with two UBXs. I have each TX/RX antenna
on subdev A connected to each other (with 40 dB of attenuation), same for
each B subdev. I have all the RX2 antennas terminated.
I see the tones on regardless of the subdev/antenna combination. I also
tried connecting a spectrum analyzer to the TX/RX antenna ports and saw no
tones. I also put an antenna on my spectrum analyzer and saw no tones over
the air with the antenna right next to each X310.
On Fri, Jul 17, 2015 at 11:19 AM, Marcus Müller <usrp-users at lists.ettus.com>
> 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?
> Best regards,
>  http://files.ettus.com/schematics/ubx/ubx.pdf
>  http://files.ettus.com/manual/page_general.html#general_tuning_process
> 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 listUSRP-users at lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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