Satellite radio is transmitted over an fm frequency with a weak signal. For example if you set the Sirius transmitter to be broadcast on 107.9, WEBE would overwhelm it and the sat. signal would be overpowered. The lower end of the fm dial typically have little programming, which makes it ideal for the satellite transmitter to give you a clear, strong signal. 88.1 is usually one of the default presets when setting up XM or Sirius. It is very common to be at a traffic light and while scanning through your dial, latch onto someone's Sat. signal from a car nearby