[time-nuts] high (spacial) precision GPS in Kickstarter
Magnus Danielson
magnus at rubidium.dyndns.org
Sat Jan 25 12:56:54 UTC 2014
On 25/01/14 11:42, Anders Wallin wrote:
> AFAIK 'normal' RTK does not provide a clock solution. There's something
> called 4D RTK which does:
> http://saegnss1.curtin.edu.au/Publications/2010/Feng2010Four.pdf
> apparently the results can be very good - but I think the errors quoted are
> for time-transfer between two RTK receivers (?).
>
> If there are papers comparing time-transfer with dual-frequency PPP to this
> 4D RTK I'd be interested..
I think you need to differentiate between common-view time-transfer and
the precision you get from the system itself.
RTK uses the carrier phase corrections achieved from known position to
kind of high-speed delta signals as received in it's neighbourhood. This
affects both the position and time shifts of the receiver. If the RTK
base also has a good timebase and is maintained in a good way time-wise,
then both position and time gets good corrections.
It's about the same type of errors as you get in the difference between
common-view time-transfer comparisons.
If you only do L1 C/A RTK, then naturally you will benefit from the RTK
as you have no double frequency observations of your own. If you have
double-frequency receiver, RTK assist to work on the tropospheric
corrections and sat orbit and time errors for which a pure double
frequency receiver isn't able to crack on it's own.
Cheers,
Magnus
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