B5C GPS Interference Revisited

I am revisiting the B5C GPS blockage problem from nearby FM broadcast signals and curious if anyone has isolated the B5C in a shielded enclosure or moved indoors and feed a GPS signal from a quality outside GPS antenna, kinda like a re-radiation scenario? Seems odd that there are 5 other GPS systems at the same site with no problems at all.

I did a simple bench test with a +18dBm signal generator and 30" whip adjacent to the B5c case, no modulation, simulating a carrier only local “FM Station”. I started at 88.1 and incremented 200 kHz up to 107.9 allowing the GPS signal to stabilize at each step . What I found was the GPS reception was mostly good except when the simulated FM station came up on a few frequencies, it totally wiped out all satellites. I am making up an Excel graph to show results.