{"id":627427,"date":"2026-01-19T00:35:57","date_gmt":"2026-01-18T23:35:57","guid":{"rendered":"https:\/\/cronologia-universale.it\/1990-11\/"},"modified":"2026-01-19T00:35:57","modified_gmt":"2026-01-18T23:35:57","slug":"1981-20","status":"publish","type":"post","link":"https:\/\/cronologia-universale.it\/en\/1981-20\/","title":{"rendered":"1981"},"content":{"rendered":"<p>Wisconsin. Construction of the ELF (Extremely Low Frequencies) project begins. It involves 84 miles of antennas, communicating at 76Hz and 45Hz with deep-sea nuclear submarines. Due to the low frequency required for the depth, the system is very slow, taking 15 minutes to transmit three letters of the alphabet. It consumes 2.6MW and will be completed in 1989. It will be abandoned in 2004 when it becomes obsolete. It is a much smaller version of the SANGUINE project, proposed in 1968. SANGUINE would have occupied 40% of the state of Wisconsin&#8217;s subsoil with over 10,000 km of buried copper cable. The system would have consumed 800MW from 100 power plants located in reinforced underground bunkers.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Wisconsin. Construction of the ELF (Extremely Low Frequencies) project begins. It involves 84 miles of&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[41],"tags":[],"class_list":["post-627427","post","type-post","status-publish","format-standard","hentry","category-s-en"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.0 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>1981 - Cronologia Universale<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/cronologia-universale.it\/en\/1981-20\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"1981 - Cronologia Universale\" \/>\n<meta property=\"og:description\" content=\"Wisconsin. 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