I haven't checked it, but the FE5680A has 1pps on pin 6.
There is no documented way to sync the FE5680A 1pps to an external
reference.
You could set an extreme value in the freq offset and wait for the 1pps
to drift
into place.
Measurements of the delay between 1pps signals depend on the accuracy of
the measuring
device - e.g., the timebase in the counter of oscilloscope X axis.
On 12/28/2011 10:45 AM, Bob Smither wrote:
Chris Albertson wrote:
Just got my fe5680 yesterday. Seems to work but the fe5680 is the most
accurate reference I have. So how to test it? I plan to buy a
Thunderbolt but until then, anyone have any creative ideas?
<snip>
Going to have to get a Thunderbolt. I have an Oncore UT+ the provides a
good pulse per second but that will not help
You can take the FE-5680 10MHz and divide it down to a derived 1 PPS.
Use the time interval measurement on your HP5328A to measure the TI
between the Oncore 1 PPS (start) and the derived 1 PPS (stop).
You might want to set a finite TI (for example, 100 usec) by adjusting
the phase of the derived 1 PPS so the measurement doesn't get confused.
I have done this using an HP5316B with good results.
The jitter on the GPS 1 PPS might limit your short term resolution,
but over a day or so you should be able to measure the drift of the
FE-5680A.
I have used a Ref Tek 111A GPS clock for the 1 PPS. That unit has a
lot (several usec) of jitter. I recently started using a 111C that
has much lower jitter (a few 10's of nsec). I believe your OnCore
unit will be similar.
Here are some results from my tracking my FE-5680A:
http://c-c-i.com/image/tid/4
Most recent:
http://c-c-i.com/node/159
Hope this helps.
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--
Chuck Forsberg WA7KGX N2469R [email protected] www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430
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