[time-nuts] ? phase comparison or other device

Magnus Danielson magnus at rubidium.dyndns.org
Sun Jul 1 18:46:36 EDT 2007

From: Dr Bruce Griffiths <bruce.griffiths at xtra.co.nz>
Subject: Re: [time-nuts] ? phase comparison or other device
Date: Mon, 02 Jul 2007 10:02:44 +1200
Message-ID: <46882484.4030002 at xtra.co.nz>

> Bob
> What is the application for which you want to use injected out of band 
> noise?
> Since the performance of a well designed zero-crossing detector is 
> equivalent to a 25 bit ADC when locating the zero-crossing, it will be 
> difficult to replicate this performance using a lower resolution ADC 
> even combined with out of band dithering.
> In practice, diode clamp circuit distortion in a zero-crossing detector 
> isn't an issue.

We soon will have well-tested ZCDs of "sufficient" resolution at our hands
here on the list. They will be fairly easy to duplicate. As we combine findings
of different origins I think alot will be gained.

Now, would interferometric approaches lower our 1/f noise floor in the mixers?
I have been considering multiple insertion polyphase filters in order to
acheive the equalent of a 0/180 degree combiner network but for 10 MHz where
such approaches would be bulky unless built by coaxes, which certainly would be
possible to acheive. Any opinions?


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