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

[Azelio Boriani]

In your opinion, is it possible for a GPS receiver to align the PPS pulse
on multiple of the C/A code repetition rate because of (for example) badly
received satellite signals? Maybe this can happen, after the initial
acquisition, on the following updates.

On Wed, Feb 1, 2012 at 10:47 AM, <bg at lysator.liu.se> wrote:

> > 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 classic GPS receiver architecture use early and late correlators to
> track the correlation peak. You can make fresh single fix solutions as
> quick as your hardware can cope. However the correlator tracking loops
> have a limited bandwidth - 5 to 25Hz-ish. It is of limited interest to
> sample quicker than some 10-40Hz.
>
> --
>
>    Björn
>
>
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