[time-nuts] FE-5680A arrived

Bob Camp lists at rtty.us
Wed Jan 11 18:04:38 UTC 2012


To use the 1 pps with a normal (RS-232 based) NTP server, you would need a
pulse stretcher. You probably could use it directly with one of the Soekris
boards that take the pps straight into a GPIO pin.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Chris Albertson
Sent: Wednesday, January 11, 2012 12:50 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FE-5680A arrived

On Wed, Jan 11, 2012 at 9:09 AM, Bob Camp <lists at rtty.us> wrote:
> Hi
> A good old logic probe can come in handy from time to time. They certainly
> aren't very expensive.

On my FE5680 I was convinced there was no PPS.  My HP5328 counter
could not find a pulse.    All I saw was high frequency noise on the
scope.  And the spec listed pin-6 as "N/C".  Then I thought to amplify
and low pass filter and now the PPS shows up on the HP5328 with a
1000000.0 uS period.

I think the PPS is there but needs a bit a signal conditioning to be
useful.  Fortunately my old Tek 465B scope has a low pass function and
a vertical amplifier output BNC on the rear.  I had to crank the amp
up and attenuate it on the counter.

Has anyone been able to put the PPS fronmthe FE5680 to practical use
yet.  For example sending it to a computer to drive an NTP server?
Detecting it is one thing. reliable use 24x7 is another thing.

Chris Albertson
Redondo Beach, California

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