{"id":9737,"date":"2018-03-09T08:50:52","date_gmt":"2018-03-09T07:50:52","guid":{"rendered":"http:\/\/projectes.xtec.cat\/zenit\/?p=9737"},"modified":"2023-02-15T09:26:43","modified_gmt":"2023-02-15T08:26:43","slug":"p05_ud01-0-titol-0","status":"publish","type":"post","link":"https:\/\/projectes.xtec.cat\/zenit\/general\/p05_ud01-0-titol-0\/","title":{"rendered":"1.1. Detecci\u00f3 d&#8217;objectes"},"content":{"rendered":"<div class=\"container\">\n<ul class=\"nav nav-tabs nav-pills\">\n<li class=\"nav-item\"><a class=\"nav-link active\" href=\"#consulta\" data-toggle=\"tab\">Consulta<\/a><\/li>\n<p>  <!--\n\n<li class=\"nav-item\"><a class=\"nav-link\" href=\"#practica\" data-toggle=\"tab\">Practica<\/a><\/li>\n\n\n  \n\n<li class=\"nav-item\"><a class=\"nav-link\" href=\"#aplicacions\" data-toggle=\"tab\">Aplicacions<\/a><\/li>\n\n\n  \n\n<li class=\"nav-item\"><a class=\"nav-link\" href=\"#recursos\" data-toggle=\"tab\">Recursos<\/a><\/li>\n\n-->\n<\/ul>\n<div class=\"tab-content\" style=\"margin-top: 20px;\">\n<div id=\"consulta\" class=\"tab-pane active\">\n<p>L&#8217;emissor del sistema radar emet una ona de r\u00e0dio en una direcci\u00f3 determinada, que es reflecteix en els objectes que troba en el seu cam\u00ed. L&#8217;ona reflectida \u00e9s captada amb m\u00e9s o menys intensitat pel receptor del sistema radar al cap d&#8217;un temps determinat, i aix\u00f2 permet determinar la dist\u00e0ncia a la que es troba l&#8217;objecte. La intensitat del senyal de retorn est\u00e0 relacionada amb les dimensions de l&#8217;objecte i de quins materials est\u00e0 fet. Pel qu\u00e8 fa al moviment dels objectes, es determina a partir de la freq\u00fc\u00e8ncia de l&#8217;ona reflectida; en cas que la freq\u00fc\u00e8ncia sigui diferent a l&#8217;original, es pot saber si l&#8217;objecte s&#8217;est\u00e0 apropant o allunyant, i amb quina velocitat (efecte Doppler).<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/9\/91\/Sonar_Principle_CA.svg\/496px-Sonar_Principle_CA.svg.png\" alt=\"Sonar Principle CA\" width=\"506\" height=\"271\" \/><\/p>\n<p>Per tal de prendre mesures al voltant del sistema de radar dels objectes que l&#8217;envolten, la unitat emissora ha d&#8217;estar prove\u00efda d&#8217;un sistema mec\u00e0nic que, gr\u00e0cies a un motor, faci les escombrades necess\u00e0ries en les diferents direccions d&#8217;inter\u00e8s.<\/p>\n<p>Per tal de detectar un objecte, el radar emet una ona de r\u00e0dio en la direcci\u00f3 que es vol examinar i analitza l&#8217;ona que retorna un cop reflectida en l&#8217;objecte. En funci\u00f3 de la informaci\u00f3 instant\u00e0nia que es vol obtenir, es fan servir m\u00e8todes diferents :<\/p>\n<ul>\n<li>Determinaci\u00f3 de la <strong>dist\u00e0ncia<\/strong> : S&#8217;obt\u00e9 mesurant el <strong>temps<\/strong> de retorn de l&#8217;ona.<\/li>\n<li>Determinaci\u00f3 de la <strong>velocitat<\/strong> : S&#8217;obt\u00e9 mesurant la <strong>freq\u00fc\u00e8ncia<\/strong> de l&#8217;ona reflectida.<\/li>\n<\/ul>\n<p>Fes un cop d&#8217;ull a les animacions que hi ha a continuaci\u00f3 per con\u00e8ixer aquests m\u00e8todes. A sota de les animacions hi ha els c\u00e0lculs matem\u00e0tics necessaris per obtenir la informaci\u00f3. Despr\u00e9s pots practicar l&#8217;us d&#8217;aquests c\u00e0lculs.<\/p>\n<p style=\"text-align: center;\"><strong><a id=\"determinacio\"><\/a>DETERMINACI\u00d3 DE LA DIST\u00c0NCIA<\/strong><\/p>\n<p><center><iframe loading=\"lazy\" style=\"border: 0px;\" title=\"Reflexi\u00f3 d'un front d'ona\" src=\"https:\/\/www.geogebra.org\/material\/iframe\/id\/fegsFXUq\/width\/1024\/height\/300\/border\/888888\/smb\/false\/stb\/false\/stbh\/false\/ai\/false\/asb\/false\/sri\/false\/rc\/false\/ld\/false\/sdz\/false\/ctl\/false\" width=\"1024px\" height=\"300px\" scrolling=\"no\"> <\/iframe><\/center><\/p>\n<p style=\"text-align: center;\">El temps que triga a retornar el front d&#8217;ona reflectit permet determinar la dist\u00e0ncia a l&#8217;objecte. (<a href=\"https:\/\/www.geogebra.org\/material\/show\/id\/fegsFXUq\">GeoGebra<\/a>)<\/p>\n<p style=\"text-align: left;\">Si l&#8217;ona es propaga a trav\u00e9s d&#8217;un mitj\u00e0 amb una velocitat <em><strong>c<\/strong><\/em> (m\/s. En el buit, c=300.000.000 m\/s), la dist\u00e0ncia <em><strong>d<\/strong><\/em> a l&#8217;objecte detectat (m) es pot calcular a partir del temps de retorn <em><strong>t<\/strong><\/em> (s) de l&#8217;ona :<\/p>\n<h4 style=\"text-align: center;\"><em><strong>d = c \u00b7 t \/ 2<\/strong><\/em><\/h4>\n<p>&nbsp;<\/p>\n<p style=\"text-align: center;\"><strong>DETERMINACI\u00d3 DE LA VELOCITAT<\/strong><\/p>\n<p style=\"text-align: center;\"><iframe loading=\"lazy\" style=\"border: 0px;\" title=\"Efecte Doppler\" src=\"https:\/\/www.geogebra.org\/material\/iframe\/id\/XJQAyRDq\/width\/1024\/height\/400\/border\/888888\/smb\/false\/stb\/false\/stbh\/false\/ai\/false\/asb\/false\/sri\/false\/rc\/false\/ld\/false\/sdz\/false\/ctl\/false\" width=\"1024px\" height=\"400px\" scrolling=\"no\"> <\/iframe><\/p>\n<p style=\"text-align: center;\">Efecte Doppler. L&#8217;ona reflectida per l&#8217;objecte en moviment es rep amb una freq\u00fc\u00e8ncia diferent a la de l&#8217;ona original. (<a href=\"https:\/\/www.geogebra.org\/material\/show\/id\/8106337\">GeoGebra<\/a>)<\/p>\n<p style=\"text-align: center;\">Si l&#8217;objecte detectat s&#8217;allunya del radar amb una velocitat <em><strong>v<\/strong><\/em> (m\/s), la freq\u00fc\u00e8ncia detectada <em><strong>f<\/strong><\/em> (Hz) es pot calcular a partir de la freq\u00fc\u00e8ncia original <em><strong>f0<\/strong><\/em> (Hz) :<\/p>\n<h4 style=\"text-align: center;\"><em><strong>f = f0 \u00b7 c \/ (c + v)<br \/>\n<\/strong><\/em><\/h4>\n<p>&nbsp;<\/p>\n<p style=\"text-align: center;\"><strong>PRACTICA :<\/strong><\/p>\n<p style=\"text-align: center;\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-2\" class=\"h5p-iframe\" data-content-id=\"2\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"C\u00e0lculs\"><\/iframe><\/div><\/p>\n<\/div>\n<div id=\"practica\" class=\"tab-pane fade\">\n<h2>Practica<\/h2>\n<\/div>\n<div id=\"aplicacions\" class=\"tab-pane\">\n<h2>Aplicacions<\/h2>\n<\/div>\n<div id=\"recursos\" class=\"tab-pane\">\n<h2>Recursos<\/h2>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<ul class=\"nav nav-tabs nav-pills\">\n<li class=\"nav-item\"><a class=\"nav-link active\" href=\"#consulta\" data-toggle=\"tab\">Consulta<\/a><\/li>\n<\/ul>\n<p>L&#8217;emissor del sistema radar emet una ona de r\u00e0dio en una direcci\u00f3 determinada, que es reflecteix en els objectes que troba en el seu cam\u00ed. L&#8217;ona reflectida \u00e9s captada amb m\u00e9s o menys intensitat pel&hellip;  <a href=\"https:\/\/projectes.xtec.cat\/zenit\/general\/p05_ud01-0-titol-0\/\" title=\"Read 1.1. Detecci\u00f3 d&#8217;objectes\">Llegeix m\u00e9s\u00bb<\/a><\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"footnotes":""},"categories":[1,330],"tags":[306,318],"class_list":["post-9737","post","type-post","status-publish","format-standard","hentry","category-general","category-obsterra","tag-plafo","tag-ud_radar"],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/projectes.xtec.cat\/zenit\/wp-json\/wp\/v2\/posts\/9737","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/projectes.xtec.cat\/zenit\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/projectes.xtec.cat\/zenit\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/projectes.xtec.cat\/zenit\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/projectes.xtec.cat\/zenit\/wp-json\/wp\/v2\/comments?post=9737"}],"version-history":[{"count":4,"href":"https:\/\/projectes.xtec.cat\/zenit\/wp-json\/wp\/v2\/posts\/9737\/revisions"}],"predecessor-version":[{"id":11386,"href":"https:\/\/projectes.xtec.cat\/zenit\/wp-json\/wp\/v2\/posts\/9737\/revisions\/11386"}],"wp:attachment":[{"href":"https:\/\/projectes.xtec.cat\/zenit\/wp-json\/wp\/v2\/media?parent=9737"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/projectes.xtec.cat\/zenit\/wp-json\/wp\/v2\/categories?post=9737"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/projectes.xtec.cat\/zenit\/wp-json\/wp\/v2\/tags?post=9737"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}