GPS interference

[jsgbrl]

As a point of interest does the GPS diagnostics drop out when driving around or is the GPS on the phone/navman/whatever OK when moving?

yes sir, moving or parked, the is no gps signal lock.

[jsgbrl]

when i disconnected the car battery, the gps tracker was directly connected to the battery so i assume no earthing problems

[BillsGU]

Other than using a spectrum analyser and scanning the frequency spectrum inside the vehicle for anything that should not be there - this problem has me stumped!