[time-nuts] Strange GPS behaviour

Magnus Danielson magnus at rubidium.dyndns.org
Sun Dec 30 13:17:41 UTC 2012


On 30/12/12 13:56, Azelio Boriani wrote:
> and maybe that reflashing a 1uS nav receiver to have a 100nS timing
> receiver is related only to firmware improvements.

Most probably. A possibility would be to have a bad running state, but 
this should not be the case and then a firmware upgrade should be needed 
anyway.

It would be interesting to see the release notes for the GPS receiver in 
question, so that one could see if there was any major issue behind it.

Changed T-RAIM limit to prune out false-tickers more effectively?

> Accurate timing is mandatory for accurate position/navigation. The
> CW12 timing receiver has a position hold mode that can't be turned
> off but always gives the computed position.

It should be noted that a timing mode should be able to still produce 
navigation solutions as a by-product, it's just that it is not allowed 
to steer the time and "current" position of the receiver. Then again, 
getting detailed pseudo-range information is even better if you want to 
post-process.

I assume that carrier-phase smoothed code tracking is being used today, 
rather than code tracking only. The new generation of receivers are much 
more black box receivers compared to the traditional receivers.

Cheers,
Magnus




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