that, as in the cinema, a wide screen display, MAC signals are capable of conveying component originated video viewed at a distance of about three or four times picture height, has signals and an accompanying sound in sync audio signal over significantly more impact than pictures with the standard aspect networks conforming to CCIR Recommendations 567 and 965. If ratio of 4:3 (width/height). For domestic viewing, market research the SNR set out in these Recommendations is exceeded, the subjec- tends to confirm that wide screen pictures, even of conventional tive performance of T-MAC is better than PAL. Below this mini- resolution, are preferred by the great majority of viewers. This has mum SNR, the noise is more noticeable in T-MAC than in PAL, but led to increased interest in various techniques, including the MAC the pictures may still appear better because cross colour effects are family, that can provide improved quality, wide screen pictures absent. without increasing the basic scanning rates of conventional systems T-MAC was originally conceived as a means of transmitting the and are fully compatible with those systems. Some of these 'en- signals available from analogue component ENG equipment to hanced' or 'advanced' systems are suitable for transmission on studio centres, using existing transmission circuits. The following terrestrial as well as satellite channels. MAC luminance and chrominance compression ratios apply to routeing and contribution links, etc.: 57.2.4.1 HD-MAC S-MAC component 4:2:2 signals R-Y/B-Y component 4:1:1 signals Y 9 R-Y/B-Y A European Eureka EU-95 project in which a large number of T-MAC component 4:2:0 signals Y 3:2 R-Y/B-Y organisations have co-operated is to develop a compatible HDTV component 3:1:0 signals Y 4:3 R-Y/B-Y satellite transmission and will make proposals to the CCIR for HDTV production and transmission standards. The project, initiated 57.2.4 Enhanced and high definition systems in 1986, concerns all aspects of HDTV, from programme produc- tion, recording and distr