{"id":352,"date":"2012-11-08T01:28:13","date_gmt":"2012-11-07T23:28:13","guid":{"rendered":"https:\/\/zz-indigo.mavipet.sk\/?p=352"},"modified":"2019-10-29T18:04:59","modified_gmt":"2019-10-29T18:04:59","slug":"dds-oscilatory-zamyslenie-2","status":"publish","type":"post","link":"https:\/\/zz-indigo.mavipet.sk\/?p=352","title":{"rendered":"DDS oscil\u00e1tory zamyslenie (2)"},"content":{"rendered":"<p>V mojom d\u00e1vnej\u0161om \u010dl\u00e1nku <a title=\"Clanok\" href=\"https:\/\/zz-indigo.mavipet.sk\/?p=221\">DDS oscil\u00e1tory zamyslenie<\/a> som sa zam\u00fd\u0161\u013eal nad d\u00f4vodmi ktor\u00e9 vedu ludi nepou\u017e\u00edva\u0165 DDS ako NCO ale sign\u00e1l preh\u00e1\u0148aj\u00fa cez doln\u00e9 priepuste a potom z nich sp\u00e4tne robia obd\u013a\u017enikov\u00fd priebeh.\u00a0 Tento \u010dl\u00e1nok je zalo\u017een\u00fd na z\u00e1veroch z emailovej komunik\u00e1cie p\u00e1na ktor\u00fd sa mi ozval. Jeho email som bohu\u017eia\u013e stratil.<\/p>\n<p><!--more-->Na za\u010diatok si treba uvedomi\u0165 p\u00e1r veci.<\/p>\n<ul>\n<li>Obe spom\u00ednan\u00e9 kon\u0161trukcie vyu\u017e\u00edvaj\u00fa sp\u00ednan\u00e9 zmie\u0161ava\u010de<\/li>\n<li>Sp\u00ednan\u00e9 zmie\u0161ava\u010de vy\u017eaduj\u00fa presn\u00fa striedu 50:50 inak v\u00fdsledn\u00fd sign\u00e1l obsahuje zv\u00fd\u0161en\u00fa hladinu \u0161umu.<\/li>\n<li>NCO oscil\u00e1tory nezaru\u010duj\u00fa striedu 50:50. Napr\u00edklad pri Fout=1\/3Fclk je to 60:40 (ak som to spr\u00e1vne odhadol)<\/li>\n<\/ul>\n<p>Vyu\u017e\u00edvanie DDS zo &#8222;sinus&#8220; priebehom a doln\u00fdmi priepustami (Dokument\u00e1cia v\u00fa\u010d\u0161inov odpor\u00fa\u010da doln\u00fa priepust 7radu) je postavene na jednoduchej myslienke.<\/p>\n<p><a title=\"Odkaz na &quot;nudnu&quot; matematiku\" href=\"http:\/\/pleione.asu.cas.cz\/~slechta\/fourier\/fourier.html\">Furierove rady! <\/a><\/p>\n<p>Tie s\u00fa postaven\u00e9 na fakte, ze ka\u017ed\u00fd periodick\u00fd priebeh sa d\u00e1 rozlo\u017ei\u0165 na s\u00fa\u010det viacer\u00fdch harmonick\u00fdch frekvencii. A ke\u010f\u017ee ide\u00e1lna doln\u00e1 priepust vy\u0161\u0161ie harmonick\u00e9 odfiltruje mal\u00fd by sme dosta\u0165 s\u00ednusov\u00fd priebeh o ide\u00e1lnej striede. Teraz sa ponuka ot\u00e1zka a pre\u010do sa DDS pou\u017e\u00edva zo s\u00ednusov\u00fdm priebehom ke\u010f podla te\u00f3rie rovnak\u00e9ho v\u00fdsledku \u010dlovek dosiahne aj z obd\u013a\u017enikov\u00fdm priebehom? Odpove\u010f je jednoduch\u00e1. Ne\u017eijeme v ide\u00e1lnom svete. A aj filtre nie s\u00fa ide\u00e1lne a preto je v\u00fdhodn\u00e9 im \u010do najviac pom\u00f4c\u0165. A a &#8222;odzoban\u00e1&#8220; s\u00ednusovka z DDS m\u00e1 menej vy\u0161\u0161\u00edch harmonick\u00fdch ako kr\u00e1sny obd\u013a\u017enik.<\/p>\n<p>Tak\u017ee teraz je u\u017e jasn\u00e9 pre\u010do sa kon\u0161trukt\u00e9ri uberali t\u00fdmto smerom.<\/p>\n<p>Ale osobne si mysl\u00edm \u017ee v\u00fdsledok nebude adekv\u00e1tny vynalo\u017eenej snahe. D\u00f4vod? LC obvody nepoznaj\u00fa matematiku \ud83d\ude09 A t\u00fdm p\u00e1dom ani furierov\u00e9 rady. Doln\u00e1 priepust je vlastne integra\u010dn\u00fd \u010dlen. A toho nezauj\u00edma \u010do sa bude dia\u0165 za par mikrosek\u00fand.<\/p>\n<p>Na druhu stranu je nutne prizna\u0165 ze takto upraven\u00fd priebeh bude mat lep\u0161i pomer striedi ako zdrojov\u00fd sign\u00e1l. A to je aj cie\u013eom sna\u017eenia kon\u0161trukt\u00e9rov.<\/p>\n<p>Ale s\u00fa aj in\u00e9 mo\u017enosti ako dosiahnu\u0165 sign\u00e1l po\u017eadovanej striedy? Iste.<\/p>\n<ul>\n<li>Delenie Fout z DDS, Tym sa v rovnakom pomere zni\u017euje aj chyba.<\/li>\n<li>Pou\u017e\u00edvanie DDS kde Fclk je podstatne vy\u0161\u0161ia. Rovnak\u00fd v\u00fdsledok ako predch\u00e1dzaj\u00faca mo\u017enos\u0165.<\/li>\n<li>Pou\u017eivanie PLL a VCO<\/li>\n<li>Pou\u017e\u00edvanie DDS spolu z VCO ovl\u00e1dan\u00fdm PLL. Podla m\u0148a najlep\u0161\u00ed sp\u00f4sob.<\/li>\n<\/ul>\n<p>Aj ke\u010f sa to nezd\u00e1 nieto rie\u0161enia nemusia by\u0165 a\u017e tak n\u00e1ro\u010dn\u00e9. Probl\u00e9mom sk\u00f4r b\u00fdva ze DDS ktor\u00e9 zvl\u00e1daj\u00fa vy\u0161\u0161ie Fclk maj\u00fa nevhodn\u00e9 p\u00fazdra a pou\u017e\u00edvaj\u00fa ve\u013emi n\u00edzke nap\u00e1jacie nap\u00e4tia. Posledn\u00e1 mo\u017enos\u0165 sa zd\u00e1 byt ve\u013emi n\u00e1ro\u010dn\u00e1 na zapojenie ale existuj\u00fa u\u017e hotov\u00e9 rie\u0161enia ako napr\u00edklad ICS512<\/p>\n<p>Ak sa mi na poste nestrat\u00ed viano\u010dn\u00fd dar\u010dek od man\u017eelky (Osciloskop DSO203) Tak sk\u00fasim vygenerova\u0165 nejak\u00e9 obr\u00e1zky priebehov.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>V mojom d\u00e1vnej\u0161om \u010dl\u00e1nku DDS oscil\u00e1tory zamyslenie som sa zam\u00fd\u0161\u013eal nad d\u00f4vodmi ktor\u00e9 vedu ludi nepou\u017e\u00edva\u0165 DDS ako NCO ale sign\u00e1l preh\u00e1\u0148aj\u00fa cez doln\u00e9 priepuste a potom z nich sp\u00e4tne robia obd\u013a\u017enikov\u00fd priebeh.\u00a0 Tento \u010dl\u00e1nok je zalo\u017een\u00fd na z\u00e1veroch z &hellip; <a href=\"https:\/\/zz-indigo.mavipet.sk\/?p=352\">Pokra\u010dova\u0165 v \u010d\u00edtan\u00ed <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-352","post","type-post","status-publish","format-standard","hentry","category-ostatne"],"_links":{"self":[{"href":"https:\/\/zz-indigo.mavipet.sk\/index.php?rest_route=\/wp\/v2\/posts\/352","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zz-indigo.mavipet.sk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zz-indigo.mavipet.sk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zz-indigo.mavipet.sk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zz-indigo.mavipet.sk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=352"}],"version-history":[{"count":1,"href":"https:\/\/zz-indigo.mavipet.sk\/index.php?rest_route=\/wp\/v2\/posts\/352\/revisions"}],"predecessor-version":[{"id":2747,"href":"https:\/\/zz-indigo.mavipet.sk\/index.php?rest_route=\/wp\/v2\/posts\/352\/revisions\/2747"}],"wp:attachment":[{"href":"https:\/\/zz-indigo.mavipet.sk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=352"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zz-indigo.mavipet.sk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=352"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zz-indigo.mavipet.sk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=352"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}