[time-nuts] "Best" GPSDO

Chris Albertson albertson.chris at gmail.com
Sat Sep 29 03:31:36 UTC 2012


On Fri, Sep 28, 2012 at 5:29 PM, Bob Camp <lists at rtty.us> wrote:
> HI
>
> Sort of an open ended question, but there is a fairly simple couple answers:
>
> SInce it's close in phase noise and not far removed, things like PLL's are going to transfer it directly from the reference to the output. It will of course scale by 20 log N where N is the amount you multiplied or divided the reference frequency by. Double the frequency and the phase noise goes up by 6 db.

So in my example case of scaling the 10Mhz t-bolt to 14.5Mhz  Assuming
a perfect DDS chip the T-Bolt's phase noise would be scaled up by 20
Log(1.45)     I'm assuming this works, that I can go from 10MHz to
120Mhz and then to 14.5MHZ and the total effect is the same as going
directly from 10 to 14.5, except for the noise the equipment
introduces as added.

You can guess the real question here: "how good does the 10MHz
reference need to be to test real-world receivers?






-- 

Chris Albertson
Redondo Beach, California



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