{"id":93,"date":"2020-04-10T15:38:37","date_gmt":"2020-04-10T15:38:37","guid":{"rendered":"https:\/\/fletch.scot\/wp\/?p=93"},"modified":"2020-09-02T10:37:41","modified_gmt":"2020-09-02T10:37:41","slug":"x-phase-more-theory","status":"publish","type":"post","link":"https:\/\/fletch.scot\/wp\/?p=93","title":{"rendered":"X-Phase &#8212; More theory"},"content":{"rendered":"<p>The advert is from\u00a0<em>Practical Wireless<\/em> February 1987.<\/p>\n<p>In my last blog I tried to explain how a QRM Eliminator works. Here\u2019s some more information.<\/p>\n<p>Suppose the signal you are trying to hear is a sine wave (shown in blue). The signal as received (shown in red) will have some noise added as it travels to you.<img loading=\"lazy\" decoding=\"async\" title=\"orig-noise.png\" src=\"https:\/\/fletch.scot\/wp\/wp-content\/uploads\/2020\/09\/orig-noise.png\" alt=\"Original noise\" width=\"598\" height=\"449\" border=\"0\" \/><\/p>\n<p>The QRM eliminator allows you to pick up the noise with your noise aerial and phase shift by 180\u00ba. As shown in this chart.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" title=\"noise.png\" src=\"https:\/\/fletch.scot\/wp\/wp-content\/uploads\/2020\/09\/noise.png\" alt=\"Noise\" width=\"598\" height=\"449\" border=\"0\" \/><\/p>\n<p>If you add the blue and red signal together you\u2019d get a zero signal. So if you mix the inverted noise with the noisy signal as received you\u2019ll recover the original signal.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" title=\"recovered.png\" src=\"https:\/\/fletch.scot\/wp\/wp-content\/uploads\/2020\/09\/recovered.png\" alt=\"Recovered\" width=\"598\" height=\"449\" border=\"0\" \/><\/p>\n<p>Of course reality is different and the recovered signal won\u2019t be as clean as that. Also if you don\u2019t match the noise and main signal amplitudes properly, you\u2019d then get something like this.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" title=\"recovered-loud.png\" src=\"https:\/\/fletch.scot\/wp\/wp-content\/uploads\/2020\/09\/recovered-loud.png\" alt=\"Recovered loud\" width=\"598\" height=\"449\" border=\"0\" \/><\/p>\n<p>These charts were made with <a href=\"http:\/\/www.mathworks.com\">MATLAB<\/a> using <a href=\"..\/code\/xphase.m\">this script<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The advert is from\u00a0Practical Wireless February 1987. In my last blog I tried to explain how a QRM Eliminator works. Here\u2019s some more information. Suppose the signal you are trying to hear is a sine wave (shown in blue). The signal as received (shown in red) will have some noise added as it travels to &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/fletch.scot\/wp\/?p=93\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;X-Phase &#8212; More theory&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":95,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12],"tags":[49,34],"class_list":["post-93","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-radio","tag-noise","tag-radio"],"_links":{"self":[{"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=\/wp\/v2\/posts\/93","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=93"}],"version-history":[{"count":3,"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=\/wp\/v2\/posts\/93\/revisions"}],"predecessor-version":[{"id":153,"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=\/wp\/v2\/posts\/93\/revisions\/153"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=\/wp\/v2\/media\/95"}],"wp:attachment":[{"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=93"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=93"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fletch.scot\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=93"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}