On 1/26/19 5:00 AM, John Ackermann. N8UR wrote:
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.
or even simpler, use the counter to count the time between 1pps ticks.
Direct reading of the OCXO frequency.
John
On Jan 26, 2019, 7:15 AM, at 7:15 AM, "Richard (Rick) Karlquist"
<[email protected]> 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
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