[time-nuts] ensemble oscillators for better stability

Tom Holmes tholmes at woh.rr.com
Fri Dec 28 20:32:40 UTC 2012


Seems like I saw an article in QEX a year or two back where a guy did just
that, except he used a single 5 MHz oscillator and used the mixer to make a
doubler, but that isn't very much different from this.

Tom Holmes, N8ZM
Tipp City, OH
EM79


> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of John Ackermann N8UR
> Sent: Friday, December 28, 2012 3:20 PM
> To: Discussion of precise time and frequency measurement
> Cc: time-nuts at febo.com
> Subject: Re: [time-nuts] ensemble oscillators for better stability
> 
> Hi Corby -- I've often thought of the idea of mixing two 5 MHz sources in
a DBM
> and using the resulting 10 MHz, so I'm really curious to see how this
works out.
> Seems like injection locking  is the most likely problem you'd have to
deal with.
> 
> Let us know how this goes!
> 
> John
> 
> On Dec 28, 2012, at 2:12 PM, cdelect at juno.com wrote:
> 
> > Hi,
> >
> > I've been playing around with 2 HP 5065A standards to see if averaging
> > them will give better stability.
> >
> > The results so far are:
> >
> >                     1 sec        10 sec    100 sec
> > unitA            1.28-12    3.83-13   1.33-13
> > unitB            9.31-13    3.44-13   1.18-13
> > combined     8.95-13    3.09-13   8.95-14
> >
> > Each unit was adjusted for equal amplitude into a resistive power
> > combiner and also adjusted so their phase was coincident prior to
> > starting the plots.
> > The main problem was getting their relative frequencies close enough
> > so that there was no drift during the measurements.
> > Not a trivial accomplishment for the 100 sec tau!
> >
> > I'm thinking now of a way to loosely lock the phase of one unit to the
> > other to simplify the setup.
> >
> > One different idea I had that I'd like some feedback on:
> >
> > If I take both units into a double balanced mixer, then take the
> > resulting 10MHz and divide it back to 5MHz would I get the same
> > improvement?
> >
> > This method would be much simpler!
> >
> > Happy New Year!
> >
> > Corby Dawson
> >
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