CARFAX: The effects of co-channel interference

Subjective tests are performed to obtain further information concerning co-channel interference in "CARFAX" and, in particular, to obtain protection ratios for the practical cases in which more than one interfering signal exists or in which an occasional interfering START or FINISH signal can be heard. The term 'protection ratio' is assumed to be the margin by which the wanted field-strength must (in planning the service) exceed the sum of the powers of the interfering field strengths considered, in any part of wanted service area. The term 'interference ratio' is used to denote the ratio by which the wanted field-strength exceeds the sum of the powers of the interfering field strengths considered, at a given geographical location.