On Olsen Mem Highway in minneapolis I get a ka warning, only at night after 12am and only traveling twards the city, never away. I got the first bleep of ka 3.5 miles before I had to turn off of the road. The signal never goes to the side, and it never goes any higher than 2 on the signal meeter. Yesterday I was on my way home and got the 3.5 mile warning again and decided to track it down, as soon as I passed where I usually turn off it went away, I drove maybe another mile or so down the road and got nothing, as soon as I turned around I got a K band that I have never seen before, and only got that warning going away from the city. Does anyone know what can cause this?