 Sales Service, Place des Nations, CH-1211, ture (which determines the amount of blue or green in peak white). Geneva 20, Switzerland). The standard adopted in Europe is Illuminant D corresponding to 6500K. 57.2.2 Bandwidth To define completely the luminance and chrominance informa- tion, a colour source, such as a camera, analyses the light from the The maximum upper frequency of a video signal is governed by the scene in terms of its red (R), green (G) and blue (B) components by picture content and the scanning standard being used. For the UK means of optical filters and then gamma corrects these to take into System I this is normally taken as 5.5MHz. account differences between source and display tube characteristics. Were conventional double sideband AM to be used, this would Gamma corrected signals are termed R', G', B' signals which are imply a maximum vision bandwidth of 2 X 5.5 = 11MHz. In processed to provide the basic luminance signal (Y). The green and addition, further bandwidth would be required for the sound signal. red signals contribute more to luminance than blue and in practice In view of the restricted frequency spectrum at v.h.f. and u.h.f., it Table 57.2 Composite colour video signals in terrestrial systems (simplified) System Chrominance Chrominance subcarrier (MHz) Chrominance subcarrier modulation Eu Ev Approx. 4.43 Suppressed carrier AM of two subcarriers in quadrature (3.58 for M/PAL) E1, Eo Approx. 3.58 Suppressed carrier AM of two subcarriers in quadrature SECAM DR DB Approx. 4.41 (DR) Frequency modulation alternating one line DR one line DB (line sequential) Approx. 4.25 (DB) 57/6 Video transmission Table 57.3 Television systems by country. (* V.h.f. band only) System Country I/PAL Angola* Botswana Hong Kong Ireland Lesotho South Africa UK B G/PAL Albania Algeria Australia Austria Bahrain Bangladesh* Belgium Brunei Darussalam* Cameroon Denmark Equatorial Guinea* Ethiopia Finland Germany (FRG) Ghana Gibraltar Iceland India* Indonesia* Israel Italy Jordan Kenya Kuwait Liberia* Luxembour