is degree of resolution. by Equation 57.2 where f is the line frequency and is the field The ability to resolve fine detail depends on visual acuity, and our frequency. Television transmission 57/7 5.5 MHz 1.25 MHz 1.3 MHz Luminance Luminance chrominance Video (MHz) r.f. lower edge of channel +1.25 +3.25 +5.25 +7.28 i.f. (MHz) receiver 40.75 Figure 57.4 The frequency bands occupied by colour picture components and sound signal from an ideal 625 line System 1 transmitter as related to video, vision, and the i.f. of a receiver (BREMA standard i.f.) (57.2) multiplex of such component signals within the channels available in Bands I, III, IV, V or the 12GHz DBS/FM bands. Additionally, The way in which colour information is transmitted in the PAL component signals would not be compatible with existing black and System 1 standard is shown in Figures 57.7 to 57.10. white, PAL, SECAM or NTSC receivers. There would also be great difficulty in retaining accurate timing (phasing) of separate anal- ogue component signals during routeing or over distribution links. 57.2.3 Analogue component hybrid systems A digitally based system that permits the time division multiplex- ing of YUV analogue signals into a form suitable for DBS/FM The picture impairments inherent where the colour information is transmission within the 27MHz channels (19MHz carrier separ- encoded within the luminance signal ('mixed highs') for PAL, ation) was developed initially by the IBA and subsequently adopted NTSC and SECAM can be eliminated by maintaining the three for DBS in Europe in the early 1980s. This system (now comprising fundamental component signals representing red (R), green (G) and a family of systems) is termed Multiplexed Analogue Components blue (B) or, more practically, by separation of the luminance (Y) and (MAC), with the separate YUV signals digitally time compressed colour difference (U, V, or I, Q) chrominance signals. However, if and then time division multiplexed to occupy the active line periods the RGB or YUV signals are maintain