Policy Implications of Two Newly Identified Modes of Interference in the FM Broadcast Band

摘要

Two unforeseen modes of interference in the FM band have come to light. First, some current models of radio receivers can radiate intermodulation products when they are turned off. This case study shows how that happens and raises the larger question of whether the FCC should direct manufacturers to prevent the radiation of passive intermodulation in electronics that are connected to antennas. The second interference situation arises from the broadcasts of a pirate radio station in proximity to an HD Radio1 transmitter on a nearby channel. In addition to the direct interference pirate radio causes to potential listeners, this particular situation affected the operation of the legitimate station's HD Radio transmitter. Recommendations on protecting from such corruption of transmitter performance are presented.