{"id":453,"date":"2020-04-14T13:31:46","date_gmt":"2020-04-14T13:31:46","guid":{"rendered":"https:\/\/ejmilton.uk\/?page_id=453"},"modified":"2020-10-08T13:35:28","modified_gmt":"2020-10-08T13:35:28","slug":"noaa-images","status":"publish","type":"page","link":"https:\/\/ejmilton.uk\/index.php\/noaa-images\/","title":{"rendered":"NOAA images"},"content":{"rendered":"\n

Most data from environmental satellite sensors are inaccessible to the casual user, at least in their raw form. The exception is data from the US NOAA weather satellites, which since the 1960s have provided a data stream designed to be received by simple radio receivers operating around 137 MHz. This is known as Automatic Picture Transmission or APT, and was originally designed for simple grey-scale image capture and display on basic hardware e.g. fax machines. APT is likely to be phased out as the existing NOAA satellites are decommissioned. There are currently (2020) three operational NOAA satellites<\/a>: NOAA-15, NOAA-18 and NOAA-19, each of which typically provide two images per day of most areas of the Earth (one am, one pm), depending upon latitude.<\/p>\n\n\n\n

At Bridport I receive data from NOAA-19 using a home-made antenna in the loft which is connected to a dedicated computer that automatically receives the data and formats it into images that are then displayed on my website. The data take the form of an audio signal that is fed into the line-in socket of the PC.<\/p>\n\n\n\n

When setting-up the receiving station I experimented with two antennae, both of which are widely recommended for receiving data from NOAA satellites. The first was design known as a ‘double cross antenna’ in which four dipoles are arranged so as to respond to the right-hand circular polarisation used by NOAA APT. This worked well, but was quite large and caused an obstruction in my cramped loft. The second design, known as a quadrifilar helix antenna<\/a> was more complicated to make but gave good results and was much more compact.<\/p>\n\n\n\n

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The NOAA aerials: QFH in the foreground, DCA behind<\/figcaption><\/figure>\n\n\n\n
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An example of the images received. NOAA 19 southbound 75E at 16 Nov 2019 05:59:58 GMT on 137.10MHz, MCIR enhancement, Normal projection, Channel A: 3\/3B (mid infrared), Channel B: 4 (thermal infrared)<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

Most data from environmental satellite sensors are inaccessible to the casual user, at least in their raw form. The exception […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"_links":{"self":[{"href":"https:\/\/ejmilton.uk\/index.php\/wp-json\/wp\/v2\/pages\/453"}],"collection":[{"href":"https:\/\/ejmilton.uk\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/ejmilton.uk\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/ejmilton.uk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ejmilton.uk\/index.php\/wp-json\/wp\/v2\/comments?post=453"}],"version-history":[{"count":3,"href":"https:\/\/ejmilton.uk\/index.php\/wp-json\/wp\/v2\/pages\/453\/revisions"}],"predecessor-version":[{"id":542,"href":"https:\/\/ejmilton.uk\/index.php\/wp-json\/wp\/v2\/pages\/453\/revisions\/542"}],"wp:attachment":[{"href":"https:\/\/ejmilton.uk\/index.php\/wp-json\/wp\/v2\/media?parent=453"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}