{"id":418,"date":"2015-08-06T14:42:00","date_gmt":"2015-08-06T14:42:00","guid":{"rendered":"http:\/\/machineryequipmentonline.com\/video-equipment\/uncategorized\/tv-cameras-and-analogue-colour-encodingchrominance-circuits\/"},"modified":"2015-08-06T14:42:00","modified_gmt":"2015-08-06T14:42:00","slug":"tv-cameras-and-analogue-colour-encodingchrominance-circuits","status":"publish","type":"post","link":"http:\/\/machineryequipmentonline.com\/video-equipment\/tv-cameras-and-analogue-colour-encodingchrominance-circuits\/","title":{"rendered":"TV CAMERAS AND ANALOGUE COLOUR ENCODING:CHROMINANCE CIRCUITS."},"content":{"rendered":"<div class=\"gudph6a0dbd96f41b7\" ><script type=\"text\/javascript\">\n\tatOptions = {\n\t\t'key' : '61e5902552e2353963d8d2f1bd1f4a8f',\n\t\t'format' : 'iframe',\n\t\t'height' : 250,\n\t\t'width' : 300,\n\t\t'params' : {}\n\t};\n<\/script>\n<script type=\"text\/javascript\" src=\"\/\/www.highperformanceformat.com\/61e5902552e2353963d8d2f1bd1f4a8f\/invoke.js\"><\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.gudph6a0dbd96f41b7 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.gudph6a0dbd96f41b7 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.gudph6a0dbd96f41b7 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.gudph6a0dbd96f41b7 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.gudph6a0dbd96f41b7 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<h4 align=\"justify\">CHROMINANCE CIRCUITS<\/h4>\n<p align=\"justify\">Fig. 6.5 shows in simpli\ufb01ed form the colour circuits of the camera. The R and B preampli\ufb01ed chroma signals pass into a matrix where they are separately added to a \u2212Y signal to render R\u2212Y and B\u2212Y components. Bandpass \ufb01lters restrict these colour difference signals to a maximum frequency of 500 kHz on their way to be <i>w<\/i><i>eighted<\/i>. The weighting reduces the amplitude of R\u2212Y and B\u2212Y to prevent overloading of ampli\ufb01ers and transmitters whose ratings are based on the standard 1 V pk-pk video signal. By reducing B\u2212Y by a factor of 2.03 (becomes 0.493 B\u2212Y, called <i>U signal<\/i>) and R\u2212Y by a factor of 1.14 (becomes 0.877 R\u2212Y, called <i>V signal<\/i>) the total excursion <\/p>\n<p align=\"justify\"><a href=\"http:\/\/lh3.googleusercontent.com\/-sCcDY-Y1VZ4\/VcNyQk-mTAI\/AAAAAAAB0XU\/iINaZeyf2pE\/s1600-h\/TV%252520CAMERAS%252520AND%252520ANALOGUE%252520COLOUR%252520ENCODING-0091%25255B2%25255D.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-bottom: 0px; border-left: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top: 0px; border-right: 0px; padding-top: 0px\" title=\"TV CAMERAS AND ANALOGUE COLOUR ENCODING-0091\" border=\"0\" alt=\"TV CAMERAS AND ANALOGUE COLOUR ENCODING-0091\" src=\"http:\/\/lh3.googleusercontent.com\/-Vj_750JKpe0\/VcNyS8rqf8I\/AAAAAAAB0Xc\/B1P5mWGLq0A\/TV%252520CAMERAS%252520AND%252520ANALOGUE%252520COLOUR%252520ENCODING-0091_thumb.jpg?imgmax=800\" width=\"244\" height=\"107\" \/><\/a> <\/p>\n<p align=\"justify\">&nbsp;of the CVBS signal is limited to max. 1.23 V on bright highly saturated colours, with the bottom tips of subcarrier cycles on highly saturated dark colours (i.e. blue, colour-bar pattern) 230 mV below black-level, as in Fig. 2.5. The U and V signals are now ready for encoding. First comes a clamping stage, whence the U and V signals enter the suppressed-carrier modulators, whose carrier inputs are derived from an IC-based SSG (Sync and Subcarrier Generator). The emerging modulated U and V signals come together in an <i>encode<\/i><i> <\/i><i>balanc<\/i><i>e <\/i>control from whose slider is tapped off the chrominance signal complete. After gain control and ampli\ufb01cation the chroma signal is added to the Y signal. <\/p>\n<h4 align=\"justify\">Generation of the swinging burst<\/h4>\n<p align=\"justify\">The V-axis subcarrier signal from the SSG already bears the required line-by-line phase reversals to conform with the PAL speci\ufb01cation. The subcarrier feed to the U modulator is on the \u2013U axis at all times, so that on line <i>n <\/i>the two available subcarrier feeds are as per Fig. 6.6(a), and on line <i>n <\/i>+ 1 as per Fig. 6.6(b). If for the duration of the burst period the ordinarily balanced U and V modulators are permit- ted to become <i>unbalanced<\/i>, \u2018carrier leaking\u2019 takes place, permitting some carrier output to appear from the modulators even when no chroma input (the R\u2212Y and B\u2212Y channels are blanked during the back porch) is present. <\/p><div class=\"omkul6a0dbd970013e\" ><script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-0778475562755157\"\n     crossorigin=\"anonymous\"><\/script>\n<!-- 300x600 television-and-video -->\n<ins class=\"adsbygoogle\"\n     style=\"display:inline-block;width:300px;height:600px\"\n     data-ad-client=\"ca-pub-0778475562755157\"\n     data-ad-slot=\"6549443290\"><\/ins>\n<script>\n     (adsbygoogle = window.adsbygoogle || []).push({});\n<\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.omkul6a0dbd970013e {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.omkul6a0dbd970013e {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.omkul6a0dbd970013e {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.omkul6a0dbd970013e {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.omkul6a0dbd970013e {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<div class=\"iwogf6a0dbd970005f\" ><script type=\"text\/javascript\">\n\tatOptions = {\n\t\t'key' : '0c1eb4c533eaedb7b996f49a5a4983a9',\n\t\t'format' : 'iframe',\n\t\t'height' : 300,\n\t\t'width' : 160,\n\t\t'params' : {}\n\t};\n<\/script>\n<script type=\"text\/javascript\" src=\"\/\/www.highperformanceformat.com\/0c1eb4c533eaedb7b996f49a5a4983a9\/invoke.js\"><\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.iwogf6a0dbd970005f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.iwogf6a0dbd970005f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.iwogf6a0dbd970005f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.iwogf6a0dbd970005f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.iwogf6a0dbd970005f {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n\n<p align=\"justify\">The balancing of the modulators (embodied in a d.c.-coupled IC) is governed by their d.c. conditions, so that if a <i>burst-\ufb02ag <\/i>pulse is applied to the modulator IC to upset balance, pure carrier will be permitted to leak into the chrominance signal, the amplitude of which will depend on the height of the burst \ufb02ag pulse. Equal amounts of \u2212U and (alternating) \u00b1V are thus produced for the duration of the <\/p>\n<p align=\"justify\">burst \ufb02ag pulse. In meeting at the slider of the encode balance control the vector-resultant of the two phases of the 4.43 MHz subcarrier are as shown by the phasors on the right-hand sides of Fig. 6.6(a) <\/p>\n<p align=\"justify\"><a href=\"http:\/\/lh3.googleusercontent.com\/-UJcQAiDvbNk\/VcNyUiaWNjI\/AAAAAAAB0Xk\/XA5C8gXNr1I\/s1600-h\/TV%252520CAMERAS%252520AND%252520ANALOGUE%252520COLOUR%252520ENCODING-0092%25255B2%25255D.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-bottom: 0px; border-left: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top: 0px; border-right: 0px; padding-top: 0px\" title=\"TV CAMERAS AND ANALOGUE COLOUR ENCODING-0092\" border=\"0\" alt=\"TV CAMERAS AND ANALOGUE COLOUR ENCODING-0092\" src=\"http:\/\/lh3.googleusercontent.com\/-WRWETs7pD2g\/VcNyWSXE81I\/AAAAAAAB0Xs\/QM6ahvjkdbg\/TV%252520CAMERAS%252520AND%252520ANALOGUE%252520COLOUR%252520ENCODING-0092_thumb.jpg?imgmax=800\" width=\"244\" height=\"137\" \/><\/a> <\/p>\n<p align=\"justify\">and (b). In fact these are the very vectors required for the swinging burst signal \u2013 \u00b145\u00b0 centred on the 180\u00b0 (\u2212B\u2212Y) axis. To maintain the required 90\u00b0 swing it is important that the leak-signal amplitudes are equal for both modulators; and to ensure correct burst amplitude (0.3 V, equal to sync pulse height in the CVBS signal) the height of the burst \ufb02ag pulse is carefully controlled.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>CHROMINANCE CIRCUITS Fig. 6.5 shows in simpli\ufb01ed form the colour circuits of the camera. The R and B preampli\ufb01ed chroma signals pass into a matrix where they are separately added to a \u2212Y signal to render R\u2212Y and B\u2212Y components. Bandpass \ufb01lters restrict these colour difference signals to a maximum frequency of 500 kHz on [&hellip;]<br \/><a href=\"http:\/\/machineryequipmentonline.com\/video-equipment\/tv-cameras-and-analogue-colour-encodingchrominance-circuits\/\" class=\"more-link\" >Continue reading&#8230;<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"aioseo_notices":[],"views":776,"_links":{"self":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/418"}],"collection":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/comments?post=418"}],"version-history":[{"count":0,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/418\/revisions"}],"wp:attachment":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/media?parent=418"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/categories?post=418"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/tags?post=418"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}