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DonG,
I would say that 17 satellites is not normal for most folks. The Estimated Position error is based on the HDOP reading which in turn is based on not the number of satellites so much as their position in the sky. In other words: more satellites does not always mean that you will have a more accurate position. It’s been a little while since I have watched the Estimated Position Error number while on the water but I don’t remember seeing anything over 10 to 12 feet that I can remember.
The GPS can not track 17 satellites at one time as it is physically impossible. There are only a maximum of 12 satellites visible at any given time (horizon to horizon) plus 2 Waas Geo stationary satellites.
However, with multiple channel receivers (50) it can track the same satellite with multiple different channel receivers. Kinda like ABC. You can pick up ABC on multiple channels, but the is only one one ABC. Thank God.
I like this GPS Satellite gif. That blue spot on earth is us (gps receiver). It is looking at the gps satellites and a counting them with respect to the horizon. These 24 + satellites rotate around the earth twice in about 24 hours.
Look at the gif and you will get the jest of the satellites rotation.
http://i188.photobucket.com/albums/z...llationGPS.gif
Tom:
That makes me dizzy [er]
Good explanation of what is being seen by the gps unit.
10 turning and 2 fixed = 12 and that is only at certain given times.
Hard to give up my classroom pointer.
Here are the 2 geo-stationary (fixed in orbit with respect to earth) WAAS satellites and their coverage with respect to us Americans.
This image was with the GR50 Receiver in Missouri and I tracked 17 Satellites:
http://i36.photobucket.com/albums/e6...m/S00106-5.png
It depends on time of day and position of satellites - I see 17 alot here. The other image was from simulator so I could show differences and explain the screen features.
So tell me how a gps can have useful data from a satellite that is not viewable on the horizon. 24 + 3 moving and 2 stationary is it for gps satellites, that is unless Al Gore has come out with a new orbiting system. It would be a stretch of the imagination to accurately calculate time domain from a satellite above china.
big woop
Don't bet on it. You git to close to the edge of the Earth and you will fall off.
Shoot... No bites on/for the Galileo Galaxy of orbiters.:confused: