On 03/14/2019 05:07 PM, Ali Dormiani via USRP-users wrote:
Hello all,
Sorry for spreading misinformation. I frequently conflate clock and LO
incorrectly. Additionally the results I posted are for an array of
multiple N310's which definitely have different clocks.
I was taught in class that carrier frequency offset happens when an
access point (AP) and client have imperfect LO's. (EX. wifi router at
2.41 GHz and laptop at 2.39 Ghz).
Looking at the block diagram, could separate LO's for each AD9361 be
the source of this phase behavior?
Independent N310s that aren't sharing a reference clock cannot be relied
upon to have consistent phase and frequency. This is normal and
expected. No two oscillators will operate at precisely the same
frequency. The more $$$ you spent on an oscillator, the higher the quality,
with a non-linear $$$ vs quality curve.
But expecting two independent radios to be on exactly the same frequency
and phase without an external, common, reference, is not
realistic at all.
On Thu, Mar 14, 2019 at 1:39 PM Damon via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>> wrote:
Hi Marcus,
The UHD Version is v3.14.0.0-rc1.
Best regards,
Damon
>> Hi Ali,
>>
>> The daughterboards have their own clock generators, but they
are not
>> exactly 'independent'. At least they don't have to be, as they
share the
>> same reference clock. Look at the block diagram:
>>
>> https://kb.ettus.com/images/9/9d/USRP_N310_N300_DB_Schematic.pdf
>>
>> and "Ref Clock" block. I don't have N310 and I know that
reality can be
>> a bit far from expectations (i.e. look at my "What makes sense
and what
>> doesn't in the way carrier frequency is set for TwinRX
currently?" post).
>>
>> But maybe the daughterboards can be configured to use that
reference clock.
>>
>>
>> Best Regards,
>> Piotr Krysik
> The LMK clock generator uses the reference clock from the
mainboard, so
> there should not be any mutual phase-jitter/drift issues. I can
test this
> on my N310 in the coming day or two.
>
> What version of UHD is in use?
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