{"id":203,"date":"2015-07-22T19:53:35","date_gmt":"2015-07-22T19:53:35","guid":{"rendered":"http:\/\/airborne.geophysicsgpr.com\/?page_id=203"},"modified":"2017-03-06T21:16:08","modified_gmt":"2017-03-06T21:16:08","slug":"vlf-totem-2a","status":"publish","type":"page","link":"https:\/\/airborne.geophysicsgpr.com\/fr\/techniques\/electromagnetique-tdem-et-vlf\/vlf-totem-2a\/","title":{"rendered":"VLF (TOTEM-2A)"},"content":{"rendered":"<div id=\"pl-203\"  class=\"panel-layout\" ><div id=\"pg-203-0\"  class=\"panel-grid panel-no-style\" ><div id=\"pgc-203-0-0\"  class=\"panel-grid-cell\" ><div id=\"panel-203-0-0-0\" class=\"so-panel widget widget_sow-editor panel-first-child panel-last-child\" data-index=\"0\" ><div class=\"texte-home-right article panel-widget-style panel-widget-style-for-203-0-0-0\" ><div\n\t\t\t\n\t\t\tclass=\"so-widget-sow-editor so-widget-sow-editor-base\"\n\t\t\t\n\t\t>\n<div class=\"siteorigin-widget-tinymce textwidget\">\n\t<p>Les lev\u00e9s \u00e9lectromagn\u00e9tiques VLF utilisent des \u00e9metteurs VLF puissants situ\u00e9s partout dans le monde pour la navigation et les communications des sous-marins. Pour les relev\u00e9s en Am\u00e9rique du Nord-Est, la station d'\u00e9mission \u00e0 Cutler, Maine, (NAA , 24,0 kHz) est normalement utilis\u00e9e.<\/p>\n<p>Cet \u00e9metteur radio \u00e9met de puissantes ondes radio (environ 2 m\u00e9gawatts) \u00e0 24 kHz qui induisent des courants \u00e9lectriques dans le sol, celles-ci se d\u00e9placent \u00e0 travers le sol, donc l'intensit\u00e9 d\u00e9pend de diff\u00e9rents facteurs tels que la distance de la source \u00e9mettrice, la conductivit\u00e9 (et de la permittivit\u00e9 di\u00e9lectrique), le volume et la profondeur des corps conducteurs. Les courants induits produisent un champ magn\u00e9tique secondaire \u00e0 la m\u00eame fr\u00e9quence, qui est d\u00e9tect\u00e9 \u00e0 proximit\u00e9 de la surface par alt\u00e9ration de l\u2019onde primaire. Ce champ secondaire est inclin\u00e9 vers le haut sur le c\u00f4t\u00e9 le plus proche du conducteur et vers le bas de l'autre c\u00f4t\u00e9, comme indiqu\u00e9 par sa quadrature. Le champ total est compos\u00e9 de deux champs primaires et secondaires (g\u00e9ophysique appliqu\u00e9e, 2e \u00e9d., Telfort).<\/p>\n<p>Le syst\u00e8me \u00e9lectromagn\u00e9tique VLF utilis\u00e9 pour ce type de lev\u00e9 est le TOTEM -2A qui emploie la fine pointe de la technologie en mati\u00e8re de circuits num\u00e9riques int\u00e9gr\u00e9s uniques, avec un intervalle de 0,1 seconde d'\u00e9chantillonnage. Le r\u00e9cepteur VLF mesure le rapport entre les composantes verticales et les composantes transversales et longitudinales de quadrature et de champ total.<\/p>\n<p>Caract\u00e9ristiques du syst\u00e8me :<\/p>\n<ul>\n<li>Capacit\u00e9 de mesure simultan\u00e9e de deux stations VLF;<\/li>\n<li>S\u00e9lection pr\u00e9cise de la fr\u00e9quence: \u00e0 partir de 15 kHz \u00e0 25 kHz; s\u00e9lectionnable pour chaque canal;<\/li>\n<li>Plage de sensibilit\u00e9 : \u00e0 partir de 130 \u03bcV \u00e0 100 mV \u00e0 20 kHz ; 3dB \u00e0 14 kHz et 24 kHz ;<\/li>\n<li>Signal passe-bande: - 3dB \u00e0 \u00b1 80 Hz ; &lt; 4 % de variation de \u00b1 50 Hz;<\/li>\n<li>Bruit interne: 1,3 \u03bcV m RMS.<\/li>\n<\/ul>\n<p>D\u00fb \u00e0 sa simplicit\u00e9, \u00e0 sa petite taille et sa facilit\u00e9 d\u2019utilisation, le syst\u00e8me Herz TOTEM-2A est un excellent ajout \u00e0 tout lev\u00e9 g\u00e9ophysique h\u00e9liport\u00e9.<\/p>\n<p>\u00a0<\/p>\n<p>\u00a0<\/p>\n<p>Pour plus d'informations, veuillez contacter notre<strong><span style=\"color: #3a5568\"> <a style=\"color: #3a5568\" href=\"mailto:info@geophysicsgpr.com\">\u00c9quipe de lev\u00e9 a\u00e9roport\u00e9<\/a>.<\/span><\/strong><\/p>\n<\/div>\n<\/div><\/div><\/div><\/div><\/div><div id=\"pg-203-1\"  class=\"panel-grid panel-no-style\" ><div id=\"pgc-203-1-0\"  class=\"panel-grid-cell\" ><div id=\"panel-203-1-0-0\" class=\"so-panel widget widget_sow-image panel-first-child panel-last-child\" data-index=\"1\" ><div class=\"panel-widget-style panel-widget-style-for-203-1-0-0\" ><div\n\t\t\t\n\t\t\tclass=\"so-widget-sow-image so-widget-sow-image-default-8b5b6f678277-203\"\n\t\t\t\n\t\t>\n<div class=\"sow-image-container\">\n\t\t<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/airborne.geophysicsgpr.com\/wp-content\/uploads\/sites\/8\/2015\/07\/M11128_QUAD_prelim-Copy.jpg\" width=\"1383\" height=\"2143\" srcset=\"https:\/\/airborne.geophysicsgpr.com\/wp-content\/uploads\/sites\/8\/2015\/07\/M11128_QUAD_prelim-Copy.jpg 1383w, https:\/\/airborne.geophysicsgpr.com\/wp-content\/uploads\/sites\/8\/2015\/07\/M11128_QUAD_prelim-Copy-194x300.jpg 194w, https:\/\/airborne.geophysicsgpr.com\/wp-content\/uploads\/sites\/8\/2015\/07\/M11128_QUAD_prelim-Copy-661x1024.jpg 661w\" sizes=\"auto, (max-width: 1383px) 100vw, 1383px\" title=\"Airborne_techniques_TOTEM_2A\" alt=\"Airborne_techniques_TOTEM_2A\" \t\tclass=\"so-widget-image\"\/>\n\t<\/div>\n\n<\/div><\/div><\/div><\/div><div id=\"pgc-203-1-1\"  class=\"panel-grid-cell\" ><div id=\"panel-203-1-1-0\" class=\"so-panel widget widget_sow-image panel-first-child panel-last-child\" data-index=\"2\" ><div class=\"panel-widget-style panel-widget-style-for-203-1-1-0\" ><div\n\t\t\t\n\t\t\tclass=\"so-widget-sow-image so-widget-sow-image-default-8b5b6f678277-203\"\n\t\t\t\n\t\t>\n<div class=\"sow-image-container\">\n\t\t<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/airborne.geophysicsgpr.com\/wp-content\/uploads\/sites\/8\/2015\/07\/IMG_3063_b.jpg\" width=\"2592\" height=\"1944\" srcset=\"https:\/\/airborne.geophysicsgpr.com\/wp-content\/uploads\/sites\/8\/2015\/07\/IMG_3063_b.jpg 2592w, https:\/\/airborne.geophysicsgpr.com\/wp-content\/uploads\/sites\/8\/2015\/07\/IMG_3063_b-300x225.jpg 300w, https:\/\/airborne.geophysicsgpr.com\/wp-content\/uploads\/sites\/8\/2015\/07\/IMG_3063_b-1024x768.jpg 1024w\" sizes=\"auto, (max-width: 2592px) 100vw, 2592px\" title=\"Heliborne Georadar and Bathymetry\" alt=\"Heliborne Georadar and Bathymetry\" \t\tclass=\"so-widget-image\"\/>\n\t<\/div>\n\n<\/div><\/div><\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Les lev\u00e9s \u00e9lectromagn\u00e9tiques VLF utilisent des \u00e9metteurs VLF puissants situ\u00e9s partout dans le monde pour la navigation et les communications des sous-marins. Pour les relev\u00e9s en Am\u00e9rique du Nord-Est, la station d&rsquo;\u00e9mission \u00e0 Cutler, Maine, (NAA , 24,0 kHz) est normalement utilis\u00e9e.Cet \u00e9metteur radio \u00e9met de puissantes ondes radio (environ 2 m\u00e9gawatts) \u00e0 24 kHz&#8230;  <a href=\"https:\/\/airborne.geophysicsgpr.com\/fr\/techniques\/electromagnetique-tdem-et-vlf\/vlf-totem-2a\/\" class=\"more-link\" title=\"Read VLF (TOTEM-2A)\">Read more &raquo;<\/a><\/p>\n","protected":false},"author":1,"featured_media":632,"parent":189,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"page-full-width.php","meta":{"content-type":"","footnotes":""},"class_list":["post-203","page","type-page","status-publish","has-post-thumbnail","hentry"],"_links":{"self":[{"href":"https:\/\/airborne.geophysicsgpr.com\/fr\/wp-json\/wp\/v2\/pages\/203","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/airborne.geophysicsgpr.com\/fr\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/airborne.geophysicsgpr.com\/fr\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/airborne.geophysicsgpr.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/airborne.geophysicsgpr.com\/fr\/wp-json\/wp\/v2\/comments?post=203"}],"version-history":[{"count":14,"href":"https:\/\/airborne.geophysicsgpr.com\/fr\/wp-json\/wp\/v2\/pages\/203\/revisions"}],"predecessor-version":[{"id":1006,"href":"https:\/\/airborne.geophysicsgpr.com\/fr\/wp-json\/wp\/v2\/pages\/203\/revisions\/1006"}],"up":[{"embeddable":true,"href":"https:\/\/airborne.geophysicsgpr.com\/fr\/wp-json\/wp\/v2\/pages\/189"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/airborne.geophysicsgpr.com\/fr\/wp-json\/wp\/v2\/media\/632"}],"wp:attachment":[{"href":"https:\/\/airborne.geophysicsgpr.com\/fr\/wp-json\/wp\/v2\/media?parent=203"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}