[time-nuts] Current state of optical clocks and the definition of the second

Bob Camp kb8tq at n1k.org
Wed Jan 14 18:14:25 EST 2015


More or less by definition:

AM noise has the sidebands in phase, PM noise has the sidebands out of phase. PM adds to no envelope power, AM adds to the envelope power. If you have purely random noise, half of the power is AM, half is PM by this approach. If you have what is effectively a SDR (high speed ADC(s), decimators, cross correlation …) doing your phase noise measurement, figuring out sidebands and phase is part of the process. With an old style single mixer approach, you switch your operating point on the mixer.


> On Jan 14, 2015, at 2:19 PM, Mike Feher <mfeher at eozinc.com> wrote:
> At those low levels, how does one differentiate between phase or AM noise? Thanks & Regards - Mike 
> Mike B. Feher, EOZ Inc.
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960 office
> 908-902-3831 cell
> -----Original Message-----
> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Bruce Griffiths
> Sent: Wednesday, January 14, 2015 1:22 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Current state of optical clocks and the definition of the second
> Although the phase noise when using optical combs to generate Rf signals is low there is no mention of the am noise.
> Bruce
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