From: Tom Corrigan (thomas.corrigan@jhuapl.edu)
Date: Fri Jul 19 2002 - 06:38:17 CDT
Actually you need 4 satellites for a complete "fix", since there are 4
unknowns so be solved for (lat,lon,alt, and "time" {receiver clock
bias}). Most will give you a 2-D position fix with 3 satellites using
altitude as a given.
There are almost always >8 satellites "visible", but terrain and
folliage can block the signals depending on where you are.
Tom Corrigan
Friday, July 19, 2002, 6:26:23 AM, you wrote:
PL> One of the most important things to keep in mind when using a GPS is the
PL> number of satellites that you are able to track on. If you are in a place
PL> that you only get two tracking, your readings will not be that accurate.
PL> three is bare minimum to get a seasonably accurate fix. four or more should
PL> put you right on the money when you take a fix. There is also the
PL> possibility of difference's due to the type of unit and lots of other things
PL> that affect GPS usage. Even the expensive ones that we use in the military
PL> can be off if the conditions are not ideal for tracking in the satellites.
PL> Paul Lamson
PL> -------------------------------------------------------
PL> Scouting E-mail Discussion Lists @ usscouts.org
PL> Subscribe/Unsubscribe at http://usscouts.org/lists/
PL> Listserv Commands at http://usscouts.org/lists/lc.asp
PL> -------------------------------------------------------
PL> Send listserv commands to: listserv@troop47.com
PL> Send postings to: philmont@troop47.com
PL> List FAQ found at: http://usscouts.org/lists/faq.asp
PL> List Administrator: philmont_owner@troop47.com
PL> -------------------------------------------------------
PL> As you gather around this virtual campfire with fellow
PL> Scouts and Scouters, do your best to be trustworthy,
PL> loyal, helpful, friendly, courteous, kind, obedient,
PL> cheerful, thrifty, brave, clean and reverent.
PL> -------------------------------------------------------
-------------------------------------------------------
Scouting E-mail Discussion Lists @ usscouts.org
Subscribe/Unsubscribe at http://usscouts.org/lists/
Listserv Commands at http://usscouts.org/lists/lc.asp
-------------------------------------------------------
Send listserv commands to: listserv@troop47.com
Send postings to: philmont@troop47.com
List FAQ found at: http://usscouts.org/lists/faq.asp
List Administrator: philmont_owner@troop47.com
-------------------------------------------------------
As you gather around this virtual campfire with fellow
Scouts and Scouters, do your best to be trustworthy,
loyal, helpful, friendly, courteous, kind, obedient,
cheerful, thrifty, brave, clean and reverent.
-------------------------------------------------------
This archive was generated by hypermail 2.1.7 : Thu Mar 13 2003 - 10:38:05 CST