Wolf DL4YHF wrote:
Alberto, can you share your results with me ? I'd like to know the
jitter of the 1-pps-output, and how the unit works when there is very
limited view of the sky (which is the problem here, and also the
reason why I haven't given up the idea of building a Loran-disciplined
reference yet).
Wolf,
sure, as soon as I will have found the exact specs of this GPS, I will
send them to you.
But from a "feature sheet" about it, it is possible to read :
------
• Enhanced algorithms provide superior navigation performance in “urban
canyon” and foliage environments
• Adaptive threshold-based signal detection for improved
reception of weak signals
------
The jitter specs, although I haven't found any number for them, judging
from similar units, should not be
spectacular, on the order of a few hundreds of ns. This means that in
writing the software for your GPSDO
you will have to filter it more heavily. I have experimentally found
that a Kalman filter does wonders for
this. The other side of the medal is that the error signal will react
much more slowly to phase changes of
the oscillator, which in turn implies that you will have to use a very
good OCXO, e.g. an HP 10811 and not
an Isotemp as I have done in my GPSDO project. So my advice is to get
hold of a 10811 on eBay before
they are all sold and disappear....
73 Alberto I2PHD
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