{"id":137,"date":"2015-09-01T15:40:00","date_gmt":"2015-09-01T15:40:00","guid":{"rendered":"http:\/\/machineryequipmentonline.com\/video-equipment\/uncategorized\/the-digital-tv-receptiondvb-terrestrial-channel-decoder\/"},"modified":"2015-09-01T15:40:00","modified_gmt":"2015-09-01T15:40:00","slug":"the-digital-tv-receptiondvb-terrestrial-channel-decoder","status":"publish","type":"post","link":"http:\/\/machineryequipmentonline.com\/video-equipment\/the-digital-tv-receptiondvb-terrestrial-channel-decoder\/","title":{"rendered":"The digital TV reception:DVB terrestrial channel decoder."},"content":{"rendered":"<div class=\"wcwdh6a0dbb7bb6eab\" ><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.wcwdh6a0dbb7bb6eab {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.wcwdh6a0dbb7bb6eab {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.wcwdh6a0dbb7bb6eab {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.wcwdh6a0dbb7bb6eab {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.wcwdh6a0dbb7bb6eab {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<h3 align=\"justify\">DVB terrestrial channel decoder<\/h3>\n<p align=\"justify\">The main components of a DTTV front end or channel decoder are shown in Figure 18.6. The tuner receives UHF-modulated signals from the terrestrial aerial, selects the appropriate channel and produces a modulated VHF IF. Before the IF can be processed, it is fed into a <i>down-converter <\/i>to produce what is known as a low IF. The down-converter removes the UHF carrier and retains the baseband signal with a centre frequency of 4.75 MHz or thereabouts, depending on the chipset used. The low IF is digitised by an ADC using a sampling frequency derived from the OFDM demodulator. The OFDM demodulator retrieves the original modulating transport stream and sends it to the FEC decoder.  <\/p>\n<p align=\"justify\">The down-converter consists of a mixer followed by a lowpass filter. The function of a mixer is to change the frequency of an input signal. This is carried out by \u2018mixing\u2019 the original signal (frequency <i>f<\/i>1) and a separate signal (frequency <i>f<\/i>0) obtained from a local oscillator. The two signals are multiplied by the mixer to produce two beat frequencies: the sum <i>f<\/i>1 + <i>f<\/i>0<\/p>\n<p align=\"justify\"><a href=\"http:\/\/lh3.googleusercontent.com\/-61jYFKDUx6U\/VeXGVx2xDZI\/AAAAAAAB6Kk\/EzdJYHl3prA\/s1600-h\/Television-and-Video-Technology-0078.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 and Video Technology-0078\" border=\"0\" alt=\"Television and Video Technology-0078\" src=\"http:\/\/lh3.googleusercontent.com\/-GKCZqZjdN2I\/VeXGcSOxn6I\/AAAAAAAB6LE\/Pd8gIwtbWgY\/Television-and-Video-Technology-0078%25255B2%25255D.jpg?imgmax=800\" width=\"465\" height=\"274\" \/><\/a><\/p><div class=\"cmmud6a0dbb7bb704a\" ><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.cmmud6a0dbb7bb704a {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.cmmud6a0dbb7bb704a {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.cmmud6a0dbb7bb704a {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.cmmud6a0dbb7bb704a {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.cmmud6a0dbb7bb704a {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<div class=\"kmdjm6a0dbb7bb6faf\" ><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.kmdjm6a0dbb7bb6faf {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.kmdjm6a0dbb7bb6faf {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.kmdjm6a0dbb7bb6faf {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.kmdjm6a0dbb7bb6faf {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.kmdjm6a0dbb7bb6faf {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n\n<p align=\"justify\">and the difference <i>f<\/i>1 &#8211; <i>f<\/i>0. If the local oscillator frequency <i>f<\/i>0 <\/p>\n<p align=\"justify\"><a href=\"http:\/\/lh3.googleusercontent.com\/-iUnY2sxgaug\/VeXGgJ7J0FI\/AAAAAAAB6LU\/IUh4nLf43Bg\/s1600-h\/Television-and-Video-Technology-0079%25255B1%25255D.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 and Video Technology-0079\" border=\"0\" alt=\"Television and Video Technology-0079\" src=\"http:\/\/lh3.googleusercontent.com\/-MXNaUM2sLQI\/VeXG-t5A89I\/AAAAAAAB6Mw\/Fms75L4jIeo\/Television-and-Video-Technology-0079.jpg?imgmax=800\" width=\"169\" height=\"89\" \/><\/a>  <\/p>\n<p align=\"justify\">And here where the lowpass filter comes in. If the cut-off frequency of the lowpass filter is arranged to remove 2<i>f<\/i>1 and all frequencies above 2<i>f<\/i>1, the output will contain the modulating frequency <i>f<\/i>m only. Each one of the OFDM carrier frequencies would thus produce one modulating side frequency, <i>f<\/i>m1, <i>f<\/i>m2, <i>f<\/i>m3 and so on. The summation of all these fre- quencies is the baseband having the distinctive wave shape as illus- trated in Figure 18.7.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>DVB terrestrial channel decoder The main components of a DTTV front end or channel decoder are shown in Figure 18.6. The tuner receives UHF-modulated signals from the terrestrial aerial, selects the appropriate channel and produces a modulated VHF IF. Before the IF can be processed, it is fed into a down-converter to produce what is [&hellip;]<br \/><a href=\"http:\/\/machineryequipmentonline.com\/video-equipment\/the-digital-tv-receptiondvb-terrestrial-channel-decoder\/\" 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":585,"_links":{"self":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/137"}],"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=137"}],"version-history":[{"count":0,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/137\/revisions"}],"wp:attachment":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/media?parent=137"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/categories?post=137"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/tags?post=137"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}