[time-nuts] Building a GPSDO & trouble using Jupiter-T

Attila Kinali attila at kinali.ch
Wed Feb 1 09:14:14 UTC 2012

On Tue, 31 Jan 2012 16:29:07 -0800
Chris Albertson <albertson.chris at gmail.com> wrote:

> I'm pretty sure those GPS recievers that send out more frequent data,
> at say 2Hz or 5Hz are just interpolating.  It is not more accurate.
> The GPS sats only send a frame once over 6 seconds.

As Magnus already wrote, once you have a fix, you can use code tracking
to get an updated fix up to rates of 1kHz. If you use codeless P(Y)
code tracking or carrier phase tracking you can get even higher rates.

But, you can only update an already available fix, not calculate
a fresh fix from scratch at that rate. This is because carrier phase
and codeless P(Y) code tracking has an ambiguity of the phase, which
has to be first resolved by a "conventional" fix. Once you have this,
you can use those two techniques to get fixes at high rates.

			Attila Kinali

The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
		-- Tirin, The Dispossessed, U. Le Guin

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