Re: GPS

[Chris Albertson <chrisalbertson90278@yahoo.com>]

"Ephemeris",  that word reminds me.  I think maybe I know
what's happening.

The GPS unit stores ephemeris data internally in nonvolital
memory for all sats it has seen.  They can't program
it in at the factory. The unit collects this data while in use.
If you use your GPS
a lot it will eventually store ephemeris for the entire
constellation.  I'll bet Tom typically leaves his GPS on
only for a few minutes at a time.  Others like me for example
will run the GPS outdoors for an entire weekend.

My very old four channel GPS does not store this data and takes
as long as 10 minutes to get a fix after power up.

I notice when I turn on my Garmin GPS the display shows all
the sats in view even before it shows that it has gotten
a signal from them.  Even if a sat is blocked by
some obstruction it still shows up on the display.  So Tom,
is this the case with you, it displays the sat but
shows zero signal or is the sat simply not shown?  If
the latter then your unit has not seen it yet.  Try letting
it run outdoors where it has a 360 degree horizon for a 
day or two.


--- Paul Repacholi <prep@prep.synonet.com> wrote:
> I was using my GPS at a friends place, 10 sats, 9 locked. The
> ephemeris
> data was there for all of them I think.
> 
> -- 
> Paul Repacholi                               1 Crescent Rd.,
> +61 (08) 9257-1001                           Kalamunda.
>                                              West Australia 6076
> Raw, Cooked or Well-done, it's all half baked.
> EPIC, The Architecture of the future, always has been, always will
> be.
> 
> 


=====
Chris Albertson 
  Home:   310-376-1029  chrisalbertson90278@yahoo.com
  Cell:   310-990-7550
  Office: 310-336-5189  Christopher.J.Albertson@aero.org

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