{"id":814,"date":"2023-08-14T08:45:25","date_gmt":"2023-08-14T12:45:25","guid":{"rendered":"https:\/\/wpstaging.whoi.edu\/site\/deeptow\/?page_id=814"},"modified":"2023-10-25T15:34:04","modified_gmt":"2023-10-25T19:34:04","slug":"minimag-magnetometer","status":"publish","type":"page","link":"https:\/\/website.whoi.edu\/deeptow\/facilities\/minimag-magnetometer\/","title":{"rendered":"MiniMAG Magnetometer"},"content":{"rendered":"\n\n\t<h1>MiniMAG Magnetometer<\/h1>\n\t<p>We operate a stand-alone version of the ROV Jason magnetometer for use on deep-towed camera and other platforms of opportunity. This is a small fully digital 3-axis magnetoresistor magnetometer (Honeywell model HMR2300) with an optional separate data logger system. The sensor is approximately 8 inches long 3 inches diameter in a titanium pressure housing rated to 6000 meters depth. The sensor communicates via an RS232 protocol to a separate Persistor-based datalogger that stores data to a CF card. The logger also contains a battery and can operate the system for upwards of 24 hours.<\/p>\n<strong>How the sensor works<\/strong><br \/>\nThe magnetic sensing device is built upon the phenomenon of\u00a0<a href=\"http:\/\/en.wikipedia.org\/wiki\/Magnetoresistance\">magneto-resistance.<\/a>\u00a0The sensing material changes its electrical resistance depending on the strength of the ambient magnetic field. The Honeywell sensors use a property called\u00a0anisotropic magnetoresistance (AMR).\u00a0In AMR sensors the electrical resistance varies according to the angle between the direction of electrical current and that of the magnetic field. Electical resistance has a maximum value when the current is in the same direction as the applied magnetic field. Magnetoresistive sensors are typically made of a nickel-iron (Permalloy) thin film deposited on a silicon wafer and patterned as a resistive strip.\n\n<p>We currently have three deep sea HMR2300 magnetometer sensors that we use on a variety of platforms. These are identical to the HMR sensor on ROV Jason, except that we use Impulse bulkhead connectors and cabling. Below are summary documents for these instruments:<\/p>\n<ul>\n<li><a href=\"https:\/\/website.whoi.edu\/deeptow\/wp-content\/uploads\/sites\/66\/2023\/08\/hmr231359.pdf\">Link to HMR2300-Minimag serial No. 231359<\/a><\/li>\n<li><a href=\"https:\/\/website.whoi.edu\/deeptow\/wp-content\/uploads\/sites\/66\/2023\/08\/hmr311274.pdf\">Link to HMR2300-Minimag serial No. 311274<\/a><\/li>\n<li><a href=\"https:\/\/website.whoi.edu\/deeptow\/wp-content\/uploads\/sites\/66\/2023\/08\/hmr311549.pdf\">Link to HMR2300-Minimag serial No. 311549<\/a><\/li>\n<\/ul>\n\nDr. Maurice Tivey<br \/>\n<a href=\"mailto:mtivey@whoi.edu\">mtivey@whoi.edu<\/a>\n\t\t\t\t<a href=\"https:\/\/website.whoi.edu\/deeptow\/wp-content\/uploads\/sites\/66\/2023\/08\/minimag_1.jpg\" target=\"_self\" rel=\"noopener\">\n\t\t\t\t<img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/website.whoi.edu\/deeptow\/wp-content\/uploads\/sites\/66\/2023\/08\/minimag_1.jpg\" alt=\"Mini magnetometer: HMR2300\" height=\"1200\" width=\"1600\" title=\"minimag_1\" \/>\n\t\t\t\t<\/a>\n\t\tMini magnetometer: HMR2300. Photo Credit: Maurice Tivey, WHOI.\n\t\t\t\t<a href=\"https:\/\/website.whoi.edu\/deeptow\/wp-content\/uploads\/sites\/66\/2023\/08\/minimag_2.jpg\" target=\"_self\" rel=\"noopener\">\n\t\t\t\t<img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/website.whoi.edu\/deeptow\/wp-content\/uploads\/sites\/66\/2023\/08\/minimag_2.jpg\" alt=\"Mini magnetometer (right) and datalogger+battery (left) in pressure housings.\" height=\"1200\" width=\"1600\" title=\"minimag_2\" \/>\n\t\t\t\t<\/a>\n\t\tMini magnetometer (right) and datalogger+battery (left) in pressure housings. Photo Credit: Maurice Tivey, WHOI.\n\n","protected":false},"excerpt":{"rendered":"<p>MiniMAG Magnetometer We operate a stand-alone version of the ROV Jason magnetometer for use on deep-towed camera and other platforms of opportunity. This is a small fully digital 3-axis magnetoresistor magnetometer (Honeywell model HMR2300) with an optional separate data logger system. The sensor is approximately 8 inches long 3 inches diameter in a titanium pressure&hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":305,"menu_order":4,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_relevanssi_hide_post":"","_relevanssi_hide_content":"","_relevanssi_pin_for_all":"","_relevanssi_pin_keywords":"","_relevanssi_unpin_keywords":"","_relevanssi_related_keywords":"","_relevanssi_related_include_ids":"","_relevanssi_related_exclude_ids":"","_relevanssi_related_no_append":"","_relevanssi_related_not_related":"","_relevanssi_related_posts":"","_relevanssi_noindex_reason":""},"_links":{"self":[{"href":"https:\/\/website.whoi.edu\/deeptow\/wp-json\/wp\/v2\/pages\/814"}],"collection":[{"href":"https:\/\/website.whoi.edu\/deeptow\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/website.whoi.edu\/deeptow\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/website.whoi.edu\/deeptow\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/website.whoi.edu\/deeptow\/wp-json\/wp\/v2\/comments?post=814"}],"version-history":[{"count":3,"href":"https:\/\/website.whoi.edu\/deeptow\/wp-json\/wp\/v2\/pages\/814\/revisions"}],"predecessor-version":[{"id":1085,"href":"https:\/\/website.whoi.edu\/deeptow\/wp-json\/wp\/v2\/pages\/814\/revisions\/1085"}],"up":[{"embeddable":true,"href":"https:\/\/website.whoi.edu\/deeptow\/wp-json\/wp\/v2\/pages\/305"}],"wp:attachment":[{"href":"https:\/\/website.whoi.edu\/deeptow\/wp-json\/wp\/v2\/media?parent=814"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}