Example......decades ago........seeing a track that went from Harris Hill to Europe and back.....in a few seconds. This while the glider and tracker were sitting on the grid at HHSC.......

I believe it was called, "military dithering" of the signal, because, government.

I believe it was interference from the unshielded ignition in Charlie Sprat's van as he drove by to the gate... but hey, that's my theory.