[time-nuts] Strange GPS behaviour

Jim Lux jimlux at earthlink.net
Sun Dec 30 02:51:35 UTC 2012

On 12/29/12 6:34 PM, Bob Camp wrote:
> Hi
> The gotcha is that often the "navigation" and "timing" receivers are identical in terms of hardware. There is no upgraded hardware in the timing device.
> When you put a receiver into position hold, you are telling it "I don't care about the location solution". It reduces the weight of that part of the filter. Yes, that's only one way to look at it and there are other ways to look at it.

or, another conceptual model is: I'm fixed, I know where the 
transmitting satellite is, and can calculate range and doppler a priori, 
so anything else must be local clock variation and propagation.  And you 
can average out the propagation among multiple satellites (or use one 
satellite as your timing reference)..

Particularly if you are post processing and have precise ephemeris data 
for the satellites....

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