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[time-freq] Phase noise

Randy hamradio at oz.net
Sat Feb 9 16:58:01 UTC 2008


Thanks for the background info on calibrating Cesium and Rubidium standards.
I wondered about that for quite a while...

Speaking of phase noise, maybe one of you can answer this.  If I have a
clean crystal oscillator running at, say, near 100 MHz and I want to pull it
on frequency and stabilize it I have heard of the method called 'injection
locking' where a small signal, usually from a synthesizer is coupled into
the crystal oscillator.  The synthesizer signal 'captures' the crystal and
forces it to take on the synthesizer frequency (as long as they are fairly
close, of course).  My question is, what happens to the phase noise of the
crystal oscillator?  Does it remain the same as it was before locking, or
take on the phase noise of the synthesizer, or end up somewhere in between?
I was thinking the crystal might act something like a filter to the
synthesizer and the phase noise would end up worse than the crystal alone
but a lot better than just using the synthesizer alone.  Any thoughts?

Randy, W7HR
Port Orchard, WA


************************************************



-----Original Message-----
From: time-freq-bounces at lists.tapr.org
[mailto:time-freq-bounces at lists.tapr.org] On Behalf Of Ron Meiring
Sent: Saturday, February 09, 2008 1:29 AM
To: TAPR time and frequency projects
Subject: Re: [time-freq] Re: time-freq Digest, Vol 22, Issue 1

On Sat, 09 Feb 2008 08:10:27 +1000, K&J Aggett wrote:
>As far as I am concerned, GPSDO's have distinct advantages.

Yep, but what about phase noise ..... ??
Pretty important if you are use it as a reference for your rig.
I inject the 10 Mhz direct into my TS850 (after a diode doubler it 
becomes 20 Mhz).

The frequency stability is one thing... but there is more under the 
sun. Hi.

My rubidium standard is so good, I got nothing better in terms of 
phase noise.

I think your GPSDO would not even come close .....

73 Ron VK4KDD



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