Quote:
Originally Posted by SprintTouch08
i agree. think about it, there are only what 12/16 something like that gps satellites circling the earth total. The earth is round. how many can possibly be in the line of sight at any one time? It really cant be more than a few, certainly not 10, then the other side of the globe would have little signal. the satellites are orbiting in a pattern that you always have at least 2 or 3 there for a lock at any time.
Its pretty simple if you really think about orbits around a sphere that everyone has to be covered by at least 2 or 3 at all times. the time of day may give you more locks than normal at certain times due to orbits coinciding, but you certainly arent losing the ability to get any lock during any part of the day. Its simply the flaky gps implementation we have currently on the Touch, or the weather. Clouds and bad weather contribute to impeding the signal too.
and as mentioned above there is that tower/a-gps function which is why its on the phones. It help when you only have 3 locks lets say. It will use gps PLUS tower triangulation making it as close to accurate as possible. That's why a-gps even exists or else there''d be no need for it if there was always good gps signal from many satellites. its there for those poor gps situations.
http://trl.trimble.com/dscgi/ds.py/G...upPlanning.exe here is a desktop program that will tell you the ideal gps times for your area, just for reference and to play with |
Your information is somewhat faulty. There are 28+ satellites and there are a minimum of 6 always in view by design. The satellites are 13,500 miles up (looked this up) so I imagine 1 satellite can cover 25-30%. On my dedicated Garmin hiking gps I regularly pull in 8+ at a time. Also it takes 4 satellites to get a 3d lock. Technically there is no reason for AGPS except for the weak receiver in the touch, that extra satellite does help obtain lock.
On my garmin, it can receive 3d lock in a matter of 30-45 secs after a coldstart. My older garmin however has a less sensitive receiver and it fires up like the touch after a cold restart.
The thing I dont understand is why on a cold start does the radio assume you are at 0,0 lat/lon. It seems that it would be better to write last position somewhere, and give the almanac something to work from. But I digress..