BBC R&D

Abstract

This report describes the results obtained from field strength survey of a Band V high-power experimental transmitter installed at Crystal Palace. The work was part of a comprehensive schedule of tests undertaken by several organizations to assess the potentialities of the u.h.f. band for television broadcasting. Measurements and observations for the field strength survey were made by units of the D.S.I.R. Radio Research Station, the G.P.O., and the I.T.A. and the BBC Research Department. Two principal contour maps have been produced, one as measured for an effective radiated power (e.r.p.) of 125 kW, and one for a possible e.r.p. of 1000 kW. A list of the field strength values obtained in the larger towns is also shown, together with comparable figures of the service at present provided by the Crystal Palace Band I transmitter. Using information gained from picture appraisal tests, other maps have been issued showing the areas in which a satisfactory service is available to stated proportions of the population. The technique of measurement adopted by the BBC is discussed in some detail since there have been fundamental changes as a result of experience gained from previous u.h.f. and v.h.f. methods. Work which involved picture monitoring has not been described here, as this came within the scope of separate teams primarily concerned with picture assessment.