I'm noticing that on my whistler it doesn't go off until the cop is only 50 feet away in come cases. Once I was driving down a hill with a sharp curve, he had his radar on and I was only able to detect it when he came out of the trees(There was a wooded area blocking the view of the cop). Another time I was in the city and it didn't detect it till he was 100 yards away. I thought these things detected ka a couple miles out? Do buildings and trees, hills block the radar signal? These are the only cases in which I get short ka detection. Once today The cop was facing away from me about 2-300 yards ahead and I only got a 1 on signal strength for a brief second then it stopped. I all this normal?