I've been playing with the high accuracy RTK GPS on the helicopter.
The software reports stunningly consistent positions etc....
But visually the helicopter wanders all over the world.
I've jsut solved it.
The Old GPS reports position in degrees, new GPS reports position in Radians!
Arghhhhh! Since I never actually looked at the lat lon positions I just told the vehicle to remember where "here" is and report distances from that reference point I never noticed.
I like using the binary records from the GPS's as parsing NEMA style text is a conversion that is not needed. If the binary record reports IEEE double format just use them. Alas The two GPS have different byte orders as well one is big endian one little endian, one reports velocity as heading and speed, one reports as vnorth and veast. I got all of these conversions working, but missed the radians/degrees difference. I'm tired and in a hurry, not the best situation for quality software. If NASA can make these kind of errors I guess I'm in good company. (Remember Mars Climate Orbiter?)