{"id":332,"date":"2015-08-25T14:25:00","date_gmt":"2015-08-25T14:25:00","guid":{"rendered":"http:\/\/machineryequipmentonline.com\/video-equipment\/uncategorized\/audio-record-and-playbackfrequency-multiplex\/"},"modified":"2015-08-25T14:25:00","modified_gmt":"2015-08-25T14:25:00","slug":"audio-record-and-playbackfrequency-multiplex","status":"publish","type":"post","link":"http:\/\/machineryequipmentonline.com\/video-equipment\/audio-record-and-playbackfrequency-multiplex\/","title":{"rendered":"AUDIO RECORD AND PLAYBACK:FREQUENCY MULTIPLEX"},"content":{"rendered":"<div class=\"opboc6a0dbc3e25464\" ><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.opboc6a0dbc3e25464 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.opboc6a0dbc3e25464 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.opboc6a0dbc3e25464 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.opboc6a0dbc3e25464 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.opboc6a0dbc3e25464 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<h3 align=\"justify\">FREQUENCY MULTIPLEX<\/h3>\n<p align=\"justify\">An alternative approach to the provision of high-quality sound with video is the frequency-multiplex system, used in the V8 format. V8, as part of its speci\ufb01cation, makes use of metal-powder and metal- evaporated (MP and ME) tapes, whose magnetic coating thick- nesses are only 3 and 0.15 micron respectively, and therefore unsuitable for depth-multiplex techniques. The V8 sound system caters for a monaural sound track conveyed by a single f.m. carrier at 1.5 MHz with maximum deviation of \u00b1100 kHz, see Fig. 14.3(b). Separate audio heads are not used here: the 1.5 MHz f.m. sound carrier is added to the luminance f.m. and colour-under signals for pas- sage via the recording ampli\ufb01er to the <i>video <\/i>recording heads.  <\/p>\n<p align=\"justify\">To avoid mutual interference the audio carrier writing current is held to 12 dB below nominal chroma writing current, which itself is some 6 dB below luminance writing current. Further, the relatively high video f.m. carrier frequency (4.2\u20135.4 MHz) ensures that little luminance sideband energy is present in the 300 kHz-wide spectrum- slot reserved for the f.m. audio carrier and its sidebands. In V8 the colour-under frequency is based on 732 kHz with sideband spreads of about 500 kHz, so that the upper chroma energy limit on the tape- frequency spectrum is about 1.25 MHz, again avoiding interference from the sound carrier.  <\/p>\n<p align=\"justify\">The electronic processing circuit for V8 f.m. audio is just the same as that described above, using 2:1 logarithmic compression and expansion (Fig. 17.8) carried out by the same form of r.m.s. detector and VCA. A similar VCO and PLL f.m. modem system is also used. For camcorder application an audio-recording high-pass \ufb01lter is used to cut off frequencies below 200 Hz in order to suppress wind, lens- motor and handling noises. An upper frequency limit of 15 kHz is also set in the baseband signal chain to permit correct operation of the noise-reduction circuit. During replay the off-tape f.m. audio signal is picked out by a sharp cut-off bandpass \ufb01lter centred on 1.5 MHz, then applied to a 2-\ufb01eld dropout compensation circuit. For this simpler 1-channel system a single miniature 48-pin chip caters for all audio-f.m. and noise-reduction processes during both record and playback, for which internal electronic switches are provided; such external components as are required are limited to RC and LC networks for \ufb01ltering and response shaping.  <\/p>\n<h4 align=\"justify\">Stereo in Video 8 formats<\/h4>\n<p align=\"justify\">Although the original speci\ufb01cation for V8 provided only for mono sound, a stereo variant was arranged by having a second carrier for L-R audio information at 1.7 MHz, with the \u2018mono\u2019 channel now carrying L+R information. The two channels are separated during replay in a simple add\/subtract matrix.  <\/p><div class=\"kpxbg6a0dbc3e25603\" ><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.kpxbg6a0dbc3e25603 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.kpxbg6a0dbc3e25603 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.kpxbg6a0dbc3e25603 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.kpxbg6a0dbc3e25603 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.kpxbg6a0dbc3e25603 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<div class=\"hdwds6a0dbc3e2553a\" ><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.hdwds6a0dbc3e2553a {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.hdwds6a0dbc3e2553a {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.hdwds6a0dbc3e2553a {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.hdwds6a0dbc3e2553a {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.hdwds6a0dbc3e2553a {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n\n<p align=\"justify\"><a href=\"http:\/\/lh3.googleusercontent.com\/--zZOHF13MSw\/Vdx63Gsfz0I\/AAAAAAAB1cA\/WiRAQhNt-X0\/s1600-h\/AUDIO-RECORD-AND-PLAYBACK-02152.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=\"AUDIO RECORD AND PLAYBACK-0215\" border=\"0\" alt=\"AUDIO RECORD AND PLAYBACK-0215\" src=\"http:\/\/lh3.googleusercontent.com\/-yFCJSo1kGjE\/Vdx67DfVfTI\/AAAAAAAB1cg\/G7TP3rh3XeM\/AUDIO-RECORD-AND-PLAYBACK-0215_thumb.jpg?imgmax=800\" width=\"244\" height=\"161\" \/><\/a>  <\/p>\n<p align=\"justify\">\n<p align=\"justify\"><i><\/i> <\/p>\n<p align=\"justify\">\n","protected":false},"excerpt":{"rendered":"<p>FREQUENCY MULTIPLEX An alternative approach to the provision of high-quality sound with video is the frequency-multiplex system, used in the V8 format. V8, as part of its speci\ufb01cation, makes use of metal-powder and metal- evaporated (MP and ME) tapes, whose magnetic coating thick- nesses are only 3 and 0.15 micron respectively, and therefore unsuitable for [&hellip;]<br \/><a href=\"http:\/\/machineryequipmentonline.com\/video-equipment\/audio-record-and-playbackfrequency-multiplex\/\" 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":783,"_links":{"self":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/332"}],"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=332"}],"version-history":[{"count":0,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/332\/revisions"}],"wp:attachment":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/media?parent=332"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/categories?post=332"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/tags?post=332"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}