[time-nuts] Measuring frequency rather than tuning crystal

Paul Alfille paul.alfille at gmail.com
Fri Feb 27 15:08:19 EST 2015


I don't think your TTi TF930 has a GPS input to calibrate against, based on
a quick perusal of the data sheet. I would guess that the calibration
constants are thus fixed from the factory (including temperature
coefficients).


On Thu, Feb 26, 2015 at 3:36 PM, James via time-nuts <time-nuts at febo.com>
wrote:

> I presume that this is what my TTi TF930 does. Calibration is closed box
> so I guess the TCXO is free running and the micro inside just uses
> calibration constants.
>
> James
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Paul Alfille <paul.alfille at gmail.com>
> To: Discussion of precise time and frequency measurement <
> time-nuts at febo.com>
> Sent: Thu, 26 Feb 2015 19:02
> Subject: [time-nuts] Measuring frequency rather than tuning crystal
>
>
> I have a couple of HP 5370s with the beaglebone brain transplant. They
> come
> with a nice 10811 that has a little adjustment screw.
>
> Testing against a
> Thunderbolt or KS-24361 the 5370 is off by less than 1Hz.
>
> I know the
> traditional method would be to adjust the crystal slowly and
> make careful
> measurements, but since I have a fancy computer in there, I
> wonder if I could
> just adjust the frequency in software. 64-bit floating
> point numbers should
> have sufficient accuracy. All reported measurments
> would be corrected for the
> actual reference frequency.
>
> Basically, I'd have a 10000000.226 Hz internal
> reference.
>
> In fact, could I connect the beaglebone to a a GPS 1 pps source
> and make
> this a GPS-disciplined-software-corrected oscillator.
>
> So my
> question is is this a known technique? The discipline feedback
> circuit seems a
> little different, I'd adjusting for drift and offset, but
> not the gain of
> control-oscillator
> linkage.
> _______________________________________________
> time-nuts mailing
> list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the
> instructions there.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>


More information about the time-nuts mailing list