[Loadstone] Observations

Shawn Kirkpatrick shawn at odyssey.cm.nu
Thu Nov 9 02:07:22 GMT 2006


To add a bit to what Monty said, the altitude can be quite inaccurate at 
times. There's a setting you can try, the altitude measurement setting. You 
can set it to sea level or geoid. Sea level will only work propperly if your 
receiver sends the difference between geoid and sea level. Some receivers do 
this, my old holux gr-230 does, but some don't, my current royaltek rbt-2010 
doesn't. The sea level setting would probably be the most accurate for an 
area if you're getting the correct information from the receiver. Geoid is 
an earth model where the sea level is a constant. depending on where you are 
this may or may not work. Even if you have the correct setting for your area 
the gps accuracy for altitude isn't very good. It's supposed to be within 5 
meters (15 feet) but from what I've seen it's usually not even close to 
this. I've seen it fluctuate up to 100 feet or so at a time. This is why we 
don't use the altitude for point coordinates.

On Wed, 8 Nov 2006, Aedan O'Meara wrote:

> 	Hi Shawn,
> I have tried the approach time you suggest but find that the setting of
> 30 seems too broad. The minimum seems to be 10 and this does limit the
> announcing of approaching points to a reasonable level.
> One other observation:
> The altitude is spoken consistently by Talks as -10 or -30 which would
> indicate to me that I was below sealevel whereas I am definitely above
> sealevel. Is this just a dash or a minus?
> i e is it a verbosity problem (punctuation is set to all) or a fault?
>
> Regards
> Aedan.
>
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