The measurement of teletext performance over the united kingdom television network

This paper summarizes the results of extensive Teletext field trials conducted in the UK between March 1976 and March 1978. Consideration is given to the Teletext performance of the u.h.f. television network, the extent of reception in the homes of viewers and the performance of Teletext decoders. The results indicate that the service will be predominantly field strength limited provided viewers use well-installed outdoor aerials. It is suggested that data regeneration may be used to advantage to ensure the highest possible standards of radiated performance from certain stations. This is because, to a large extent, transmitter group delay errors become more significant for Teletext than for television. The paper concludes that an adequate Teletext service is available to a high percentage of the existing television audience, provided production receivers have a decoding threshold approaching 25% eyeheight. However, it is noted that many current production receivers fall considerably short of this performance.