[time-nuts] Strange GPS behaviour

Azelio Boriani azelio.boriani at screen.it
Sun Dec 30 12:56:51 UTC 2012


and maybe that reflashing a 1uS nav receiver to have a 100nS timing
receiver is related only to firmware improvements. 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.

On Sun, Dec 30, 2012 at 12:50 PM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:

> On 30/12/12 10:06, bg at lysator.liu.se wrote:
>
>> Hi Magnus,
>>
>>  2) Timing versions might get an upgraded oscillator. Maybe a TCXO
>>>> instead
>>>> of a standard XO.
>>>>
>>>
>>> Don't think so. The noise and systematic stability is as important for
>>> positional as for timing versions, the timing version can benefit of the
>>> fixed position.
>>>
>>
>> Look at the uBlox6 lineup. Position receivers are available with XO or
>> TCXO - timing only with TCXO.
>>
>> http://www.u-blox.com/images/stories/linecards_u-blox_gps_modules_2012.pdf
>>
>
> In that case they are the first to do it to my knowledge.
>
> None of the Motorola receivers did it as I recall it. Could be that the
> price of the modules is now so low that the difference make sense.
>
> Notice that producing higher navigational rate is easy if you have the CPU
> power to do it, and todays receivers have higher CPU power than they used
> to, so doing 10 Hz navigation rate isn't unfeasable, so it does not need to
> be Kalman filter predictor results.
>
> Cheers,
> Magnus
>
>
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