[time-nuts] Correcting jitter on the 1 PPS signal from a GPSreceiver.

[Peter Reilley]

I see in the Trimble Resolution T data sheet that they
say that the PPS signal is "within 15 nS to GPS or UTC (1 Sigma) 
when using an over determined solution in stationary mode.".
I take this to mean that the PPS signal should be within 15 nS
and that comparing 2 units that there should be no more than 
30 nS between the two edges.   This is comparing the rising edges.


Pete.
 

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob Camp
Sent: Saturday, September 13, 2014 6:26 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Correcting jitter on the 1 PPS signal from a
GPSreceiver.

Hi

Where are you getting the "15 ns accuracy" number from? When I look at the
Trimble spec's they have a number of errors described (like sawtooth) that
are larger than 15 ns.

Bob

On Sep 13, 2014, at 10:41 AM, Peter Reilley <peter at reilley.com> wrote:

> I have 2 Trimble Resolution T receivers and I have compared the 1 PPS
signal
> between the 2 units.   They are spec'ed at 15 nS accuracy.    I am seeing
> about
> 80 nS of jitter between the two.   This is with about 6 satellites in
view.
> 
> I was thinking about ways to improve this.   Since this is a stationary
> installation,
> can you use the jitter in the reported location (latitude and 
> longitude) to correct for the 1 PPS jitter?
> 
> The location data is derived using the internal GPS disciplined 
> oscillator so both
> pieces of information should show the same jitter error.   If you compare
> the reported
> location with the known fixed location you should be able to use that 
> error to correct for the 1 PPS error.
> 
> Does this make sense or am I missing something?
> 
> Pete.
> 
> 
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