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Re: [Phys-l] how to prove relativity



Hmmm, another nugget about crystal oscillators for the sharing:

there are temperature compensated crystal oscillators, (TCXO)
and there are oven controlled crystal oscillators. (OCXO)
For the upper reaches of stability in this class, there are
DOUBLE ovened crystal oscillators.

The next step up from these is the GPS Disciplined Crystal oscillator. (GPSDO)
Here are some numbers to associate with these groups.


Kyocera OCXO Oven Controlled Crystal Oscillator

http://www.datasheetdir.com/OCVCXO-173A+download

Power: 12 V 12 W
short term…

Accuracy +- 1 ppb vs temperature variation (double ovened)
Accuracy +- 0.2 ppb versus voltage input variation

Long term
+- 0.025 ppm per year aging

The Next step on from Oven Controlled oscillators are GPS Disciplined Oscillators. GPSDO

These correct the oven oscillator by comparison with a timing GPS receiver input.

Hewlett-Packard: 3801

http://www.leapsecond.com/pages/z3801a-osc/


Power: 12V 5 W
Jackson Labs: Fury

http://www.leapsecond.com/pages/fury/

Power: 12V 4 W
Jackson Labs: Firefly IIA

http://www.jackson-labs.com/docs/FF-IIA_Double_Oven_specs.pdf


Accuracy +- 0.3 ppb after 3 hrs running in GPS lock
5 ppt 24 hrs


At the low end, here is what an amateur offers for sale in the GPSDO
product marketplace

(He charges under $400 at year2009 values)

Power: 12 V 4 W
J Miller G3RUH

http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm


He claims these results:
*Warm-up Accuracy*
After 30 minutes < 10^-10 typical
After 60 minutes < 10^-11

*RMS accuracy (over a 10s period)*

7x10^-12 ; that is, 99% of measurements would fall within ±2x10^-11

*Stability (Allan deviation) typical*

1s < 1x10^-12 1000s < 2x10^-12
10s < 3x10^-12 10000s < 3x10^-13
100s < 5x10^-12 1 day < 5x10^-14


He starts with a timing GPS and uses it to sync an ovened
oscillator via a VCO to drive it in a flywheel mode.

Regards

Brian W





Bernard Cleyet wrote:
Still no way.

Relativity

Satellite clocks are slowed by their orbital speed but sped up by their distance out of the Earth's gravitational well./snip/
clock much better than ~ one part in 10^10 required

/snip/

Temperature compensated crystal oscillators typically employ a thermistor network to generate a correction voltage which reduces the frequency variation over temperature.
p.s. Here's a TCXO GPS corrected for long term stability:


http://www.bmumford.com/mset/GPSref.html
/snip/
Bernard Cleyet wrote:
NO way!

bc

On 2010, Jun 02, , at 08:10, Donald Smith wrote:

synchronized the clocks on two home personal computers
/snip/