[time-nuts] FE-5680A Results so far

Chuck Forsberg WA7KGX N2469R caf at omen.com
Wed Dec 28 14:01:12 EST 2011

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 
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     caf at omen.com   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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