Distorted radio station

[iTzTeddy]

I have the Pioneer AVH-P4200DVD and the ipod compatibility is awesome, but the radio for some reason is terrible. One of my radio station works great when in parked, but when my car is in motion it is so distorted, static, random volume up and volume down, but my other radio stations works just fine, what is the problem? I've heard the same radio station on other cars and it works.