[time-nuts] Do GPS augmentation services improve 1pps?

[Poul-Henning Kamp]

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In message <C25CA8BB-C406-4821-B591-8F41B9A92600 at n1k.org>, Bob kb8tq writes:

> The uBlox F9P (navigation / survey) device does not run SBAS. Their claim
> is that things work better (for location) without it….. yikes ….

And they may well be correct about it.

The optimal position-hold position is the one which gives the smallest
residuals given the signal received.

Multipathing can easily make the optimal time-position (ie: smallest
time residual) different from the optimal position-position (ie:
smallest least-square-XYZ residual).

I played a lot with it back when I did my "RAGA"/"SNEAK" experiments[1]
and unless you _also_ use your augmentation while in pos-hold, I dont
think it is a good idea to use it get into pos-hold.

Poul-Henning

[1] see: http://phk.freebsd.dk/raga/sneak/

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