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Re: [Discuss-gnuradio] Reference Clock power level for Ettus N210
From: |
Marcus D. Leech |
Subject: |
Re: [Discuss-gnuradio] Reference Clock power level for Ettus N210 |
Date: |
Wed, 23 Apr 2014 10:40:52 -0400 |
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On 04/23/2014 09:31 AM, Marcus Müller wrote:
Hi,
looking at the N200 schematics from files.ettus.com, I'd say:
stick to the 0dBm, your clock signal has to pass a transformer and
some safety/matching circuitry and still ought to be more accurate
than the on-board VCTCXO; the clock multiplexer
(http://www.micrel.com/index.php/en/products/clock-timing/clock-data-distribution/multiplexers/article/29-sy89545l.html)
datasheet says it needs at least a voltage swing of 0.1V after that.
I'm not very much of a circuits person, but I think you won't
deteriorate much of your clock accuracy by using a clock buffer, which
are quite inexpensive (if you need but one and are not afraid to
solder... TI gives away samples for free).
Then again, you're trying to achieve a better clock performance than
the on-board 10MHz ref clock, so I guess you shouldn't start
introducing cheap hardware in the clock signal path...
Greetings,
Marcus
PS: maybe the address@hidden mailing list is better suited
for this... I've added that to CC:
I think the main thing to watch out for with clock buffers is their
linearity, since low-level non-linearity effects can increase phase-noise.
Perhaps not a lot, but a little.
I'd use a clock buffer, and see.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org