On 14/12/2014 04:08, d...@irtelemetrics.com wrote:
> Note that most high-end GNSS timing receivers go one better and
simply have an external input for the clock. That way you feed your
own lab clock into the receiver. If you have Rb/Cs/maser you would use
that as the reference. It's what the national timing labs do, along
with dual-frequency and post-processing and all the other tricks of
the trade.
I think it would be agreat idea also. It's a wonder that more of the
'timing' receivers don't have that external clock option! I wonder
what these Ublox parts use for a clock? Is it something frequency
compatible with a 10Mhz source??? (Hmm, can we pry one apart to figure
it out! ;) )
Ublox modules have a 48mhz internal clock.
There is the following interesting paragraph in at least the 7 & 8 data
sheets:
---
1.8.2 Aiding
The EXTINT pin can be used to supply time or frequency aiding data to
the receiver.
For time aiding, hardware time synchronization can be achieved by
connecting an accurate time pulse to the EXTINT pin.
Frequency aiding can be implemented by connecting a periodic rectangular
signal with a frequency up to 500 kHz and arbitrary duty cycle (low/high
phase duration must not be shorter than 50 ns) to the EXTINT pin.
Provide the applied frequency value to the receiver using UBX messages.
---
I haven't been able to find any information about what this actually
does though. Anyone know ?
Cheers
Simon
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