[time-nuts] A real world project need for timing accuracy...

[Magnus Danielson]

Mike,

On 11/02/2010 01:03 AM, Michael Baker wrote:
>     Timenutters--
>     I am trying to find a way to synchronize/coordinate
>     a downrange 10 MHz clock to the "master" 10 MHz system
>     clock at the shooting bench without spending hundreds
>     of $$ doing it.  It is not too big a problem to process
>     all of the signals from the downrange skyscreens and the
>     ultrasonic shot-group sensors and telemeter the results
>     back to the shooting bench.
>     However, time-of-flight info (via an RF link requires
>     that I sync the 10MHz clocks at both ends together.
>     Use of GPS receivers seems to be the most likely way
>     to do this but how do I keep the cost and complexity
>     down?

Either you have two OCXOs of sufficient stability, in which case you 
only need to warm them up and have the frequency tuned to the master. 
During shoot-test it is in hold-over. Reseting the time-counters when 
connected forms the common time-scale. Should give you sufficient 
accuracy. DOCXO like the OSA 8663 can be found for 30 USD. The remaining 
control comes fairly cheap.

If you go down the GPS route, no major 10 MHz tuning is really needed. 
You can do fairly simple tuning to get the precision you need. As long 
as you have PPS and serial NMEA output you can use more or less anything.

These should be fairly cheap solutions.

The time-of-flight precision needed was never really given. I'd assume 
that 100 us precision would be sufficient. Less than that is possible.

Cheers,
Magnus