Re: [Discuss-gnuradio] Reference Clock power level for Ettus N210

[Marcus D. Leech]

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