[time-nuts] Generation of very stable 10.001MHz for heterodyne freq measurement

[Richard (Rick) Karlquist]

See:

http://www.karlquist.com/FCS95.pdf

Or look at the 1995 FCS proceedings.

Rick Karlquist

John Ackermann N8UR wrote:
> Anders Time said the following on 01/25/2008 07:23 AM:
>> What is the best way to generate a very stable 10.001MHz(low E-13 or
>> -110dBc/1Hz) to be to do high resolution heterodyne(Allan deviation)
>> measurements?
>> Using DDS?
>> Using PTS 500 or 250 synth and divide? Using HP 8662A and divide?
>> Some smart pll circuit by locking the 1000Hz to the reference in some way?
>> Thanks
>> Anders
> 
> Rick Karlquist has published a design for a very low noise synthesizer
> designed for just this application.  Unfortunately, I don't have a link
> to that handy, but it's on his website.
> 
> I just took a look at some measurements I did on a PTS-250-SX51 (special
> version with low noise output to 25 MHz via an internal divider) and it
> looks like it would barely meet your requirements -- around 2x10e-13 at
> 1 second, and about -115 dBc/Hz at 1 Hz offset:
> 
> http://www.febo.com/pages/pts_synth/images/pts-250-sx51-adev.png
> http://www.febo.com/pages/pts_synth/images/pts-250-sx51-spectrum.png
> 
> However, that was at 10.000... MHz; the performance, particularly with
> respect to spurs, changes as the decimal dividers kick in for more
> complex frequencies.
> 
> John
> 
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