On Sep 2, 4:22 pm, "Jon G." <jon8...@peoplepc.com> wrote:
> The satellite signals its coordinates and time stamp to the receiver, which
> is enough information to determine the distance from the satellite to the
> receiver.  When this is done with 3 satellites, the location of the receiver
> can be found with a little math.  This math is propounded at the web page,
>
> http://mypeoplepc.com/members/jon8338/roots_to_polynomials_and_power_...

Problem is there is error associated with these three estimates due to
the ionosphere effects, clock error, etc. For this reason, 4 position
sources are almost always used for any reliable GPS receiver. In this
case, either a least-squares solution or a Newton's method starting
with what is known as a pseudo-range distance, is used.

M