{"id":191,"date":"2015-08-31T10:19:00","date_gmt":"2015-08-31T10:19:00","guid":{"rendered":"http:\/\/machineryequipmentonline.com\/video-equipment\/uncategorized\/television-receivers-crt-typesynthesised-tuning\/"},"modified":"2015-08-31T10:19:00","modified_gmt":"2015-08-31T10:19:00","slug":"television-receivers-crt-typesynthesised-tuning","status":"publish","type":"post","link":"http:\/\/machineryequipmentonline.com\/video-equipment\/television-receivers-crt-typesynthesised-tuning\/","title":{"rendered":"Television receivers CRT-type:Synthesised tuning"},"content":{"rendered":"<div class=\"fjmvj6a0dc83f6cadc\" ><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.fjmvj6a0dc83f6cadc {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.fjmvj6a0dc83f6cadc {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.fjmvj6a0dc83f6cadc {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.fjmvj6a0dc83f6cadc {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.fjmvj6a0dc83f6cadc {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<h3 align=\"justify\">Synthesised tuning<\/h3>\n<p align=\"justify\">Synthesis is the process of combining or adding up incremental amounts to obtain a certain quantity of, say, a voltage or a frequency. In the <i>f<\/i><i>r<\/i><i>equency synthesise<\/i><i>d tuner <\/i>(<i>FS<\/i><i>T<\/i>), the tuning voltage is obtained from a programmable PLL composed of the tuner\u2019s local oscillator, a controlled pre-scaler, a phase discriminator and a low-pass filter (Figure 13.8). A sample of the tuner\u2019s local oscillator frequency is fed back to the phase discriminator via a controlled divider (divide by <i>N <\/i>), known as a pre-scaler. The value of <i>N <\/i>is set by the channel select input which determines the frequency <i>f<\/i>1 going into the phase discriminator. The discriminator then compares <i>f<\/i>1 with reference frequency <i>f<\/i>r. A d.c. output is produced that reflects the difference between the two frequencies. After filtering, this d.c. voltage is used to tune the tuner to the selected channel. Synthesised PLL-controlled tuners have extremely stable output with practically no drift, thus removing the need  <\/p>\n<p align=\"justify\"><a href=\"http:\/\/lh3.googleusercontent.com\/-vHS4iOP2Qr8\/VeQpDzEQiuI\/AAAAAAAB5Nc\/q2NsRywZONU\/s1600-h\/Television-receivers-CRT-type-06652.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-right-width: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px; padding-top: 0px\" title=\"Television receivers CRT-type-0665\" border=\"0\" alt=\"Television receivers CRT-type-0665\" src=\"http:\/\/lh3.googleusercontent.com\/-rP9A7nNX3dc\/VeQpN96pC1I\/AAAAAAAB5OQ\/v3kGCRPglH4\/Television-receivers-CRT-type-0665_t.jpg?imgmax=800\" width=\"334\" height=\"313\" \/><\/a>  <\/p>\n<p align=\"justify\">for an a.f.c. circuit. The stability of the tuner output depends to a large extent on the stability of the reference frequency. For this reason, a fre- quency divider is used to divide the frequency of a crystal-controlled ref- erence oscillator by a large factor to improve its stability.  <\/p>\n<h3 align=\"justify\">The IF stage<\/h3>\n<p align=\"justify\">Recall that the IF is derived at the mixer-oscillator stage of the tuner. The local oscillator is made to oscillate at a frequency which is 39.5 MHz higher than the selected carrier frequency. The IF is then obtained by selecting the difference between the carrier and the oscillator frequencies. For exam- ple, if the TV receiver is tuned to a channel frequency of 511.25 MHz (BBC 1 transmission from Crystal Palace) then the oscillator must be tuned to frequency <i>f<\/i>o = 511.25 + 39.5 = 550.75 MHz. The relative position of the var- ious frequencies of a modulated UHF carrier may be observed on a spec- trum analyser such as that illustrated in Figure 13.9 for a modulated 511.25 MHz carrier. The 8 MHz bandwidth extends from <i>f<\/i>min to <i>f<\/i>max where  <\/p>\n<p align=\"justify\"><a href=\"http:\/\/lh3.googleusercontent.com\/-ABufykuOSwI\/VeQpRhifUUI\/AAAAAAAB5Og\/7MlR2V2r1G4\/s1600-h\/Television-receivers-CRT-type-06662.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-right-width: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px; padding-top: 0px\" title=\"Television receivers CRT-type-0666\" border=\"0\" alt=\"Television receivers CRT-type-0666\" src=\"http:\/\/lh3.googleusercontent.com\/-I_6L8MLX0bg\/VeQpbYz-b2I\/AAAAAAAB5Ow\/5eWCujFcCuQ\/Television-receivers-CRT-type-0666_t.jpg?imgmax=800\" width=\"202\" height=\"51\" \/><\/a>  <\/p><div class=\"moxpx6a0dc83f6ccc8\" ><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.moxpx6a0dc83f6ccc8 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.moxpx6a0dc83f6ccc8 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.moxpx6a0dc83f6ccc8 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.moxpx6a0dc83f6ccc8 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.moxpx6a0dc83f6ccc8 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<div class=\"hsyaf6a0dc83f6cc2f\" ><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.hsyaf6a0dc83f6cc2f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.hsyaf6a0dc83f6cc2f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.hsyaf6a0dc83f6cc2f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.hsyaf6a0dc83f6cc2f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.hsyaf6a0dc83f6cc2f {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n\n<p align=\"justify\">The sound carrier is 6 MHz above the vision carrier, so it has a frequency of 511.25 + 6.00 = 517.25 MHz.  <\/p>\n<p align=\"justify\">After the mixer-oscillator stage, the vision carrier is replaced by a vision IF of 39.5 MHz with RF oscillator frequency of 511.25 + 39.5 = 550.75 MHz.  <\/p>\n<p align=\"justify\">The sound carrier is translated into a sound IF of  <\/p>\n<p align=\"justify\"><a href=\"http:\/\/lh3.googleusercontent.com\/-QV2OrL-jMUg\/VeQpkdd2QuI\/AAAAAAAB5PI\/72rEg-tJciM\/s1600-h\/Television-receivers-CRT-type-06672.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-right-width: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px; padding-top: 0px\" title=\"Television receivers CRT-type-0667\" border=\"0\" alt=\"Television receivers CRT-type-0667\" src=\"http:\/\/lh3.googleusercontent.com\/-vPvq-eV67oQ\/VeQqN7oARxI\/AAAAAAAB5QI\/Xai6UFXfP-w\/Television-receivers-CRT-type-0667_t.jpg?imgmax=800\" width=\"362\" height=\"240\" \/><\/a>  <\/p>\n<p align=\"justify\">The sound IF is now 6 MHz <i>below <\/i>the vision IF Similarly, all other frequencies will reverse their position relative to the vision carrier when they are converted to their equivalent on the IF spectrum. <\/p>\n","protected":false},"excerpt":{"rendered":"<p>Synthesised tuning Synthesis is the process of combining or adding up incremental amounts to obtain a certain quantity of, say, a voltage or a frequency. In the frequency synthesised tuner (FST), the tuning voltage is obtained from a programmable PLL composed of the tuner\u2019s local oscillator, a controlled pre-scaler, a phase discriminator and a low-pass [&hellip;]<br \/><a href=\"http:\/\/machineryequipmentonline.com\/video-equipment\/television-receivers-crt-typesynthesised-tuning\/\" 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":669,"_links":{"self":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/191"}],"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=191"}],"version-history":[{"count":0,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/191\/revisions"}],"wp:attachment":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/media?parent=191"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/categories?post=191"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/tags?post=191"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}