[time-nuts] high (spacial) precision GPS in Kickstarter

Henry Hallam henry at pericynthion.org
Sat Jan 25 21:32:51 UTC 2014


I know the Swift Nav guys and they are working on adding various forms
of customizable timing inputs and outputs to the Piksi.  It's also an
open-source project, so it's pretty flexible in that regard.

Henry

On Sat, Jan 25, 2014 at 4:56 AM, Magnus Danielson
<magnus at rubidium.dyndns.org> wrote:
> 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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