adjacent channel interference

When the Low Power FM service was first authorized, it was as a "secondary service," though a recent court decision shows how that secondary status is becoming less and less a reality.  A secondary service is traditionally one that can be allotted where there are no other uses for a particular frequency, and which is subject to being bumped off the spectrum should there be another demand for that spectrum by a "primary" user.  LPFM stations were originally supposed to provide service to areas between full-power FM radio stations, and to be bumped off the air if there was a new FM station authorized or a change in the frequency or power of an existing station.  A decision of the Court of Appeals released earlier this month , upholding an FCC order giving more protections to LPFM stations, puts this secondary service into question.

The Court decision upheld the Commission’s decision, about which we wrote here, determining that waivers of second adjacent channel interference limitations between LPFM and full power stations should be permitted to help preserve LPFM service.  In addition, the Court upheld the FCC’s process in adopting a new "interim" policy which provides that, where an LPFM is providing 8 hours a day of local programming and would be knocked off the air by an upgrade or city of license change of a full-power station, the LPFM station could apply for a waiver of its secondary status, and there would be a rebuttable presumption in favor of such a waiver.  If the waiver is granted, the LPFM station would be preserved, and the application of the full-power station dismissed.  Thus, effectively, LPFM would no longer be secondary, but instead will have assumed a primary, protected status.


Continue Reading LPFM – When a Secondary Service Becomes Primary