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Re: PLL Phase noise and SSB



Hi John and everyone else,
    I have been "out of town" at a Answers In Genesis conference this week
and I have just got back and found 378 emails so I might be a bit slow at
replying for a while.

    Of more interest to this group, I meet a Physicist (from University of
Western Australia) who say he has built the most stable X band oscillator in
the world which he is using as part of the most accurate clock in the world.
It is a dilectric resonant oscillator! However, the dilectric is a large
synthetic saphire crystal 50mm diameter and 30mm thick and it is maintained
at 6 degrees kelvin (-267 degrees C). Saphire has a dilectric constant of
about 10. It has an unloaded Q of about 30,000,000! It has at 1 kHz offset
phase noise estimated to be -165 dbc (No currently available instrument in
the world can accurately measure it!) He is building a second one of these
oscillators to incorperate into a measuring insrutment so the phase noise
can be accurately measured. The frequency stability is 1 part in  1.26 x
10^16 or about 0.000001 Hz (one millionth of a Hz - I suppose that is 1
micro Hz) at 10 GHz!

    He is planning to build several of these clocks for us in time dilation
experiments. He is intending to build one of these clocks which can be
installed on the ISS using a radiator system on the darkside of the
spacestation to operate a version of these DROs at about 50 degrees Kelvin
(-223 degrees C). The motion of the spacestation will produce a measurable
time dilation with respect to clocks on the ground.

    While at about $200,000 each I don't supose there will be too many
amateur radio operators who could afford this type of DRO but the same was
probably said about cyrstal oscillators not so many years ago.

Regards,
Murray Peterson
VK2KGM
Sydney, NSW, Australia.

----- Original Message -----
From: "John Stephensen, KD6OZH" <kd6ozh@gte.net>
To: "Frederick M. Spinner" <fspinner@hotmail.com>; <amsat-bb@AMSAT.Org>
Sent: Sunday, January 07, 2001 6:23 PM
Subject: Re: [amsat-bb] PLL Phase noise and SSB


> At a 1 kHz offset the phase noise should be less than -65 dBc -- this
limits
> the maximum SNR to about 30 dB in a 3 kHz bandwidth. -85 dBc would be
> better. At a 10 kHz offset the phase noise should be -120 dBc or less, but
> you can live with -90 dBc if there are no strong signals near the desired
> signal.
>
> John
> KD6OZH
>
> ----- Original Message -----
> From: "Frederick M. Spinner" <fspinner@hotmail.com>
> To: <amsat-bb@AMSAT.Org>
> Sent: Saturday, 06 January 2001 05:23 UTC
> Subject: [amsat-bb] PLL Phase noise and SSB
>
>
> > One quick questions for the experts out there on Phase noise with
> > SSB signals...
> >
> > What is considered to be an acceptable and/or good amount of phase noise
> for
> > a narrowband SSB (or CW) receiver LO?  Also, is the proper measure point
1
> > KHz from the LO freq, or some other unit of measure, like "close in
phase
> > noise"?
> >
> > Fred W0FMS
> > _________________________________________________________________
> > Get your FREE download of MSN Explorer at http://explorer.msn.com
> >
> > ----
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> >
>
> ----
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>

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