From: Eugene Leitl (eugene.leitl@lrz.uni-muenchen.de)
Date: Tue Dec 21 1999 - 03:40:00 MST
Michael M. Butler writes:
> Without a good model, and without crunching the numbers, I'm not sure even
Even better, doing a real-world measurement... I noticed huge impact
of foliage, or that of _really_ heavy rainfall. Of course they don't
exactly mention this when flooding you with sales pitch. And their
battery lifetime assumes you use lithium cells while not on max
acqusition rate. Liars.
> to one significant digit _how_ impaired the accuracy would be. As you have
> said, it'd vary depending on the moment-to-moment configuration. But that's
Sat configuration has certainly an impact, but it is dwarfed by
terrain determinants. If all you see is a pitiful patch of sky between
the building roofs, while being being drowned in EM noise you can
hardly care less whether the current constellation is more or less
optimal or totally crappy.
> the cas ewhen you're out hiking in the wilderness, too. I would expect that
> my installtaion's accuracy would still be substantially better than trying
> to use the multipath reception inside an REI store.:)
>
> Eyeballing things, I'd say my dash positioning gives a view of about 2/3
> sky. '85 Mazda GLC, Left corner of dash, with plenty of driver-side window
> in view. If you have a modern car with a slant dash and airbags, your dash
> geometry may not permit as much sky to be seen. Score one more for
> preregulation technology.
Thankfully, your windshiedl doesn't seem to be sputtered with
IR-blocking muck (get a better car, fer crissakes!). For instance,
S-Bahn glass coating blocks GPS signals absolutely.
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