Allow me to add something that happened to me last week at Air Sailing Sports Contest. The first 2 days, I was getting meaningless FLARM alerts all the time + both GPSs broke lock several times. A friend asked, "how far apart are your GPS antennas? You know they are supposed to be 12" apart, don't you?
Bingo! All three were within 6" of each other. Both GPS antennas were within 4" of each other and both right behind the FLARM which has its own GPS antenna, you know?
I moved all 3 antennas about a foot from each other and the false FLARM alerts were greatly reduced and the computer GPS never broke lock again...............the Cambridge GPS did continue to drop out when near Air Sailing, but was OK when out on course. Several other contestants reported the same issue when near Air Sailing.
JJ