Hi Craig

I built my GPS sytem in 1996 using a PIC16c64. It was designed solely to calculate the yardage's on my local golf course.
The actual code I used and presumtion's I made were dirty in the extreme.
I didn't have the code space or memory to do a thorough product (although it worked well for what I needed until I dropped it in 98).
I used ratio-ing and triangulation for most of my calculations,because I knew the exact distance of each hole in yrd's (from the laser measured score card).
So to start with I located and stored the details of the middle of each green lat,long,lat dir ,long dir etc.
then I was able to (using a series of dirty cludges) ratio the actual position against yardage.