[time-nuts] Frequency standard

[John Ackermann. N8UR]

Hi Bob --

A GPSDO can replace the OCXO in your counter, and that's now most folks would use it.

If you just want to calibrate the OCXO, you don't need a GPSDO -- you can do that with just a GPS that has a pulse-per-second output, and a scope.

Use the GPS PPS to trigger the scope and adjust the OCXO for a stationary display of the OCXO waveform.  It's easiest if you use a PPS derived from the OCXO (there are inexpensive dividers that will do that) but you can also do it by looking at the 10 MHz directly -- adjust until the zero-crossing point of the sine wave stays put; when you're more than 1 Hz off you'll need a bit of guesswork, but once you get within 1 Hz you'll be looking at the same cycle position each second.  If it takes 10 seconds to drift one cycle on the display, you're 0.1 Hz off.

John

On Jan 26, 2019, 7:15 AM, at 7:15 AM, "Richard (Rick) Karlquist" <richard at karlquist.com> wrote:
>
>
>On 1/25/2019 10:06 PM, Bob Albert via time-nuts wrote:
>accuracy of only about 1 part in 20 million.  I want it somewhat
>better, 
>but no way do I need it 100 times better.  If I could set it within 0.1
>
>Hz that would be fine - it would enable frequency
>
>You're kidding yourself on the 1 part in 20 million.
>The propagation effects are such that there is
>doppler shift on the frequency that you hear that
>is much greater than that number.  You really do
>need GPS.
>
>Rick N6RK
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at lists.febo.com
>To unsubscribe, go to
>http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>and follow the instructions there.