[time-nuts] GNSS Disciplined Clock
e.roghanizad at gmail.com
Sat May 27 14:56:57 EDT 2017
As I understand from your response, 15 ns reflects the jitter, i.e. the
time difference between successive PPSs is not exactly 1 second and its
standard deviation (one sigma) is 15 ns. In that case, "precision" is more
appropriate than "accuracy" to be used in the datasheet. Moreover, how do
you infer horizontal and vertical position *accuracy*? As well, could you
please guide me to find its timing bias with respect to GNSS/UTC?
Thanks a lot
On Thu, May 25, 2017 at 8:26 PM, Bob kb8tq <kb8tq at n1k.org> wrote:
> I don’t speak for Trimble and their interpretation of all this may be a
> bit unique. Normally
> what the 15 ns means is the time out of a simulator compared to the 1 pps
> out of the module.
> Put another way, it’s just a measure of the receiver. It does not include
> any ionosphere / troposphere
> issues. It assumes a perfect estimate of the location (no bias from
> antenna multipath). IT also
> does not take into account any delay in the antenna or coax to the
> antenna. Time errors between
> Glonass and GPS are not included (bad broadcast offset estimate etc).
> Finally there is the
> fairly important qualifier of “one sigma” on the 15 ns number.
> All that said, two devices with the same antennas, same cables, close to
> each other, looking at the
> same sats, using the same systems, … should track pretty well.
> > On May 25, 2017, at 9:27 AM, Ebrahim Roghanizad <e.roghanizad at gmail.com>
> > Dear members
> > I am a new amateur member in your group. Maybe my question has been
> > Recently I found Trimble Mini-T GG, whose data sheet is attached, as a
> > GNSS disciplined time reference. I would like to know if there exists a
> > more accurate one, since it does not employ dual frequencies to
> > ionospheric delay, though it handles both GPS and GLONASS. Besides, could
> > anyone guide me about the presented accuracy in the datasheet? There, it
> > stated that "When operating in Over Determined Timing Mode, the accuracy
> > pulse per second (PPS) is within 15 nanoseconds of GNSS/UTC." Does it
> > that it includes both bias and the noise? In other words, is it true to
> > that "The time-synchronization error between two of them with a long
> > distance is less than 2*15 ns"?
> > Best Regards
> > <Trimble Mini-T GG.pdf>_______________________________________________
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