[time-nuts] Cs stability

Rob Kimberley rk at timing-consultants.com
Tue Jul 17 08:40:17 EDT 2007

Another way that has been incorporated successfully to combat g sensitivity
are accelerometers mounted on each of the x, y, Z axes of the crystal.
Combining this with spring mounts works well. g sensitivities down to e-10
per g  can be achieved.

Rob K 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of SAIDJACK at aol.com
Sent: 17 July 2007 06:14
To: time-nuts at febo.com
Subject: Re: [time-nuts] Cs stability

); SAEximRunCond expanded to false
time-nuts-bounces+rk=timing-consultants.com+rk=timing-consultants.com at febo.c

In a message dated 7/16/2007 12:10:54 Pacific Daylight Time,
SAIDJACK at aol.com writes:

>For  example tilting the Cs unit by 90 degrees will typically give an 
>of about 1E-09 or so.

>It would take some time for the  control loops to compensate for this

Hi guys,
I did tilt my 4050 when I first installed the unit, that number is from my
memory. Notice that Magnus is right of course, the Cs will compensate the
tilt,  given enough time to do so. I did not mean that the 1E-09 error will
stay permanent of course, as I said in the follow-on sentence.
Also the 4050 is not very well temperature compensated compared to modern
units, I was not impressed when I saw the FTS tempco specifications. A good
GPSDO can outperform the 4050.
I have a military OCXO sample (new product) that is supposed to be
"g-insensitive" and even that one has about E-09 frequency shift per 90
degrees  tilt.
One of the only ways to get around that is to use three crystals in  series,
with the three crystals oriented in the the XYZ axis, so their  errors
compensate out.
Vibration is also a big enemy of crystal oscillators of course.

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