Analysis of the Interference Potential of a Candidate UHF-LPTV Facility

The interference implications of the Federal Communication Commission´s recent Report and Order for the Low Power Television Service are examined using a CH 35 case short-spaced by 11 miles to a co-channel full service station. The propagation model selected is the ITS Irregular Terrain Model in the point-to-point mode employing the CONUS digital data base. Interference statistics as they relate to the propagation model are discussed. It was considered that the French formulation for the probability of interference in a Rayleigh environment was conceptually appealing since protection in location at short ranges and protection in time at greater distances can then both be accommodated in the point-to-point mode. The case analyzed demonstrates nonobjectionable interference for both offset and non-offset frequency operation, whereas the FCC contour overlap procedure would not allow the latter. A careful analysis is advised whenver DMIN is violated and the adoption of a universally accepted propagation model is urged.