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ROV JASON Magnetometer

HMR Maggie
The Honeywell HMR2300 magnetometer sensor used on ROV Jason. Photo credit: M.A. Tivey Enlarge
ROV Jason magnetometer sensor mounted on Jason
Photo, ROV magnetometer sensor mounted on the Jason. Photo credit: M. A. Tivey. Enlarge

A small fully digital 3-axis magnetoresistor magnetometer (Honeywell HMR2300) is now part of the National Deep Submergence Facility (NDSF) equipment roster for Remotely-Operated Vehicle (ROV) Jason.  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 the datalogging system of the NDSF and other Deep Submergence Lab vehicles.

How the sensor works
The magnetic sensing device is built upon the phenomenon of magneto-resistance. The sensing material changes its electrical resistance depending on the strength of the ambient magnetic field. The Honeywell sensors use a property called anisotropic magnetoresistance (AMR). In 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.

For more information on the ROV JASON magnetometer,

Dr. Maurice Tivey

Woods Hole Oceanographic Institution. All rights reserved

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