Monitored 87.9 Mhz some more today while driving. Sitting at the stop sign on 6th Ave and 205th St NE waiting for a chance to pull out in traffic and listing to noise when a strong signal emerged, remained for about three seconds, then rapidly was gone back to white noise again.
Then driving down I-5, just south of the University district, picked up a signal briefly.
All of these times it faded up very suddenly, stayed for a short duration, then faded out very rapidly.
Didn’t hear enough of it to determine what it was, one time sounded like religious music, another time sounded like Chinese music, but both times it only lasted a few seconds so not enough to really know what was going on.
It definitely was not cross-modulation, the signal was clean and only one program material. Also, at 6th, I was sitting still when the signal came up out of the noise, achieved full quieting, and then went back into the noise.