So we're on the same page: the camera and mic psu are both located in your basement and the mic is powered via Ethernet cable? How far are the camera and microphone from one another? What type of cable did you run between them for the audio signal? Changes in the atmosphere effect radio signal propagation. Assuming that's a SUNY station, I could see more variation in their broadcast than your average radio station... I suspect it might also be broadcast on AM.