[time-nuts] ensemble oscillators for better stability

Azelio Boriani azelio.boriani at screen.it
Fri Dec 28 20:38:02 UTC 2012


Which reference did you use to time your measurements?

On Fri, Dec 28, 2012 at 9:32 PM, Tom Holmes <tholmes at woh.rr.com> wrote:

> 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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>
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