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Old 11-12-2007, 03:15 PM   #22
TomW
Beastly Adventurer
 
Joined: Jan 2006
Location: Ft. Payne, AL
Oddometer: 1,013
Quote:
Originally Posted by offroute
...TomW - the SPOT rep tells me that the view to the horizon should not be biased towards the southern unless I am at more northern latitudes - I am at Lake Tahoe now. Nevertheless, so far, it sure seems south is more important than the other cardinal directions.
Yep, based on what I learned he's right about that, and so are you. I learned from my bro that their satellites are not in true polar orbits (where the satellites wouldn't favor a specific location on the earth). They're in orbits inclined at 52 degrees to the equator, meaning they won't go north of 52 degrees north latitude (or 52 degrees south latitude). Also meaning that at any given time, for those of us in the northern mid-latitudes, more satellites are likely to be south of us than north of us. Some may be overhead or north of us (as long as we're south of N52 deg), but it's slightly more likely that they'll be to the south. I don't know how significant the theoretical latitude factor is, but your informal test to date seems to bear out the generalization.

GlobalStar is having some tech issues with their satellites and from what I gather, they're pushing data applications over voice until they get their second generation birds up starting in 2009.

Interesting factoid my brother picked up: the competing sat phone system (Iridium) was planned for a constellation of 66 satellites and 11 orbiting spares for a total of 77 in polar orbits. The atomic number of iridium is 77.

I think GlobalStar looked at population distribution and decided that most people lived between N52 and S52, so a smaller number of satellites (40) could satisfactorily cover that area from inclined orbits. Clever.

Cheers.
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TomW
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