Magnetic Sensors
Honeywell Electronic Compassing Solutions

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Electronic Compasses for Personal Handheld Use, Auto Compasses, Aircraft Compasses, and Marine Compasses

Honeywell offers high accuracy compassing solutions for personal, vehicle, aircraft, and marine navigation. Our extensive experience in fabricating magneto-resistive sensors allows us to develop electronic compass modules that are suited to ground, air, and water dead reckoning. The earth's magnetic field is about 0.6 gauss in an open-air environment, and has a direction from the magnetic south pole to the magnetic north pole. This pointing to the north pole is the basis for magnetic compassing. At the equator, the magnetic field direction is entirely a horizontal vector, but as you compass further into the northern or southern hemispheres the magnetic field will point partially downwards (northern hemisphere) or upwards (southern hemisphere). This angle down or up at the earth's surface is called the inclination (dip) angle. Two-axis magnetic compasses measure the horizontal vector components of the earth's magnetic field using two sensor elements in the horizontal plane but orthogonal to each other. Called the X and Y-axis sensors, each sensor on an electronic compass assembly measures the magnetic field in its sensitive axis and the arc tangent Y/X provides the heading of the compass with respect to the X-axis. A two-axis compass can remain accurate as long as the sensors remain horizontal, or orthogonal to the gravitational (downward) vector. In moving platform applications, two axis compasses are mechanically "gimbaled" to remain flat and accurate. Three-axis magnetic compasses contain magnetic sensors in all three orthogonal vectors of an electronic compass assembly to capture the horizontal and vertical components of the earth's magnetic field. To electronically gimbal the compass, the three magnetic sensors are complemented by a tilt-sensing element to measure the gravitational direction. The tilt sensor provides two-axis measurement of compass assembly tilt, known as pitch and roll axis. The five axes' of sensor inputs are combined to create a "tilt-compensated" version of the X and Y-axis magnetic vectors, and then computed into a tilt-compensated heading. For further interest, please see the technical papers and application notes.

The HMR Family of Electronic Compass Products

Honeywell Solid State Electronics Center offers a complete line of HMR compass modules from the basic HMR3200 two-axis electronic compass to the HMR3600 with +/-80 degrees of tilt compensation.

The HMR3000 Digital Compass Module is a three-axis compass featuring 0.5 degree accuracy and a fluidic tilt sensor for +/- 45 degree compensation and digital serial bus interface (RS-485 or RS-232 options). The HMR3200 Digital Compass Solution is a module featuring two-axis compassing in horizontal or vertical PCB orientations with 1 degree of accuracy and 0.1 degree of resolution. The HMR3300 Digital Compass Solution is a module featuring three-axis compassing with an onboard MEMs accelerometer for +/-60 degree tilt sensing and up to 1 degree accuracy and 0.1 degree resolution. The HMR3400 Digital Compass Solution is a three-axis, tilt compensated electronic compass offering lower power consumption and increased miniaturization in a 0.6” x 1.5” PCB. The HMR3500 TruePoint™ electronic compass is a three-axis digital compass module with azimuth accuracy of 1 degree with 0.1 degree resolution and 0.5 degree repeatability, tilt range of ± 80°. The HMR3600 µPOINT® (micropoint) digital magnetic compass is a new generation azimuth sensor that combines the latest in gyro technology with advanced digital magnetic compass hardware and software. Azimuth accuracy is 0.5 degree with 0.1 degree resolution. Inclination range is ± 80°. The gyro compensates for short term transient magnetic disturbances, keeping the heading output accurate, even in the presence of these unexpected magnetic fields. Each compass product offers a calibration routine for compatibility for your mounting locations. Development kit versions are offered for each HMR compass product for evaluation and demonstration needs.

For specialized compass solutions, Honeywell offers the HMC line of linear-mode magnetic field sensor devices to create two and three-axis compass designs. Product designers may also choose the HMC1055 Compass Chip Set for developing custom three-axis, tilt-compensated compass platforms with a MEMSIC MEMs accelerometer for tilt sensing.