1) Using the null of a loop antenna, find a vector to the beacon using
a compass. Note the location where the vector was found on a GPS. Do
this from multiple locations and the beacon is where the lines
intersect. Since there will be error in both the compass (2 degrees
using a Garmin GPS) and some error in finding the null, the result will
be more of a locus of points where the beacon could be located rather
than the beacon itself.


I have posted a law-of-cosines calculation example several times where
coordinates of an intersection point are determined from two GPS locations
with a bearing from each location...to the intersection point. I can find
one of those in my files and post it later if that is needed.

But it could been done graphically with 'Scratch-Plot' because one of the
newer features of 'Scratch-Plot' is a plot by azimuth and distance. Just
set-up a scale of UTM coordinates, plot each GPS location in UTM
coordinates, plot a line from each location with an azimuth direction and a
dummy-distance so that the lines intersect, mouse-click a point at the
intersection of the lines, and check the coordinates of the mouse-click
point immediately in the help file or later in the plot text file.

Here is a user link to 'Scratch-Plot' :

http://www.kbhscape.com/plot.htm


Also, the difference between a geodetic direction and a UTM grid direction
can be determined with 'Geodetic/UTM-Grid Utility' by entering the latitude
and longitudes and comparing geodetic directions to grid directions.

And here is a user link to 'Geodetic/UTM-Grid Utility' :

http://www.kbhscape.com/gps.htm

I have posted a law-of-cosines calculation example several times where
coordinates of an intersection point are determined from two GPS locations
with a bearing from each location...to the intersection point. I can find
one of those in my files and post it later if that is needed.


Oh, intersection of two directions is fundamentally a law-of-sines
calculation and that is a much easier calculation than a law-of-cosines
calculation. A law-of-cosines calculation is use for the intersection of two
distances...

But it could been done graphically with 'Scratch-Plot' because one of the
newer features of 'Scratch-Plot' is a plot by azimuth and distance. Just
set-up a scale of UTM coordinates, plot each GPS location in UTM
coordinates, plot a line from each location with an azimuth direction and
a dummy-distance so that the lines intersect, mouse-click a point at the
intersection of the lines, and check the coordinates of the mouse-click
point immediately in the help file or later in the plot text file.


Compass directions with declination should also be adjusted with UTM
convergence before they are used with UTM coordinates...

"KBH" wrote in message
.. .
....
I have posted a law-of-cosines calculation example several times where
coordinates of an intersection point are determined from two GPS locations
with a bearing from each location...to the intersection point. I can find
one of those in my files and post it later if that is needed.

The free software FAA software compsys21 will do this and more
http://www.naco.faa.gov/index.asp?xm...online/compsys