[time-nuts] Re: Please help. Motorola Oncore

[Hal Murray]

> I am in NY, N 41.10.0481, W 074.11.2900, 408ft. So I enter this data into the
> initial reference position. Telling the software to set it into the position
> hold position. For the initial reference time I tried entering UTC time and
> leaving the GMT offset +0, or my local time and setting the GMT offset to -4,
> also some 

I would power cycle and try again without telling it the time or location.

Getting started is tricky for a GPS receiver.  You might have nudged it into a 
stuck/buggy state.

Doppler shift is significant and the signal is very low bandwidth.  Thus the 
receiver has to be listening on the right frequency in order to hear the 
signal from a satellite.

If it has an up to date almanac and the clock is accurate and the position is 
known, it can figure out which satellites should be visible and calculate the 
frequency to listen on.

If the clock or location is off a bit, it has to search near the predicted 
frequencies.  Warm start.

If it doesn't have an almanac, it has to do a random search of all possible 
frequency buckets to find a satellite, then download the almanac.  Cold start. 
 It's roughly 15 minutes to get the whole almanac.  The satellite may go out 
of view while that is happening.  It may find another satellite...




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