{"id":17837,"date":"2023-12-06T06:26:45","date_gmt":"2023-12-06T00:56:45","guid":{"rendered":"https:\/\/vajiramandravi.com\/current-affairs\/?p=17837"},"modified":"2025-04-05T06:58:06","modified_gmt":"2025-04-05T01:28:06","slug":"gps","status":"publish","type":"post","link":"https:\/\/vajiramandravi.com\/current-affairs\/gps\/","title":{"rendered":"What is the Global Positioning System (GPS)?"},"content":{"rendered":"<h2>About Global Positioning System (GPS)<\/h2>\n<ul>\n<li>The U.S. Department of Defence started the GPS programme in 1973 and launched the first satellite in 1978.<\/li>\n<li>The modern GPS satellite constellation\u00a0consists of 24 satellites moving around the earth in six orbits.<\/li>\n<li>Each satellite completes\u00a0two orbits in a single day.<\/li>\n<li>The overall programme has\u00a0three main components:\n<ul>\n<li>Space segment: It\u00a0consists of 24 satellites. The six orbits they occupy\u00a0are all 20,200 km above the earth, and each orbit has four satellites at all times. In this configuration, anyone on the earth will be able to \u2018see\u2019 at\u00a0least four satellites at a time.<\/li>\n<li>Control segment:\u00a0It consists of\u00a0a global network of ground-brd control stations and antennae that track the 24 satellites, make sure their performance is as expected at all times, and transmit commands.<\/li>\n<li>User segment:\u00a0It pertains to the use of GPS in various sectors and applications. The major sectors include agriculture, construction, surveying, logistics, telecommunications, power transmission, search and rescue, air travel, meteorology, seismology, and military operations.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h2>How does GPS work?<\/h2>\n<ul>\n<li>Each GPS satellite continuously broadcasts\u00a0a radio signal containing information about its location in orbit, operational status, and the time at which the signal is emitted.<\/li>\n<li>The signals are transmitted at the\u00a0L1 (1,575.42 MHz) and the L2 (1,227.6 MHz) frequencies at 50 bits\/second.<\/li>\n<li>The signals are\u00a0encoded with code-division multiple access.<\/li>\n<li>This allows multiple signals to be transmitted in the same channel and for a receiver to be able to disentangle them.<\/li>\n<li>There are\u00a0two encoding types: the\u00a0coarse\/acquisition mode, which civilians can use to access coarse GPS data, and the\u00a0precise mode, which is encrypted and is for military use.<\/li>\n<li>Being an electromagnetic signal, the radio waves travel at the speed of light.<\/li>\n<li>If the receiver has access to signals from four satellites, it will have the information required to calculate its location in four dimensions (three of space plus one of time relative to the satellite clock) \u2013 and can thus accurately triangulate its location on the ground.<\/li>\n<li>This informs the need for every point on the earth being able to \u2018see\u2019 four satellites at a time.<\/li>\n<\/ul>\n<hr \/>\n<h3>Q1) What is Radio wave?<\/h3>\n<p>These are waves from the portion of the electromagnetic spectrum at lower frequencies than microwaves. The wavelengths of radio waves range from thousands of metres to 30 cm. These correspond to frequencies as low as 3 Hz and as high as 1 gigahertz (109 Hz). Radio-wave communications signals travel through the air in a straight line, reflect off of clouds or layers of the ionosphere, or are relayed by satellites in space.\u00a0<\/p>\n<p><strong>Source: <\/strong><a href=\"https:\/\/www.thehindu.com\/sci-tech\/science\/global-positioning-system-relativity-gnss-navic-explained\/article67606417.ece\" target=\"_blank\" rel=\"nofollow noopener\"><u>How does GPS work? | Explained<\/u><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Global Positioning System satellite constellation consists of 24 satellites moving around the earth in six orbits.<\/p>\n","protected":false},"author":5,"featured_media":17838,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[],"class_list":{"0":"post-17837","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-upsc-prelims-current-affairs","8":"no-featured-image-padding"},"acf":[],"_links":{"self":[{"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/posts\/17837","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/comments?post=17837"}],"version-history":[{"count":0,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/posts\/17837\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/media\/17838"}],"wp:attachment":[{"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/media?parent=17837"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/categories?post=17837"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/tags?post=17837"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}