User Guide

NPL-4/5

System Module and User Interface Nokia Customer Care

Magnetometer Sensor

The magnetometer will be implemented with anisotropic magnetoresistive (AMR) mag-

netometer component. Two-axis linear magnetic sensors are designed as a Wheatstone

bridges formed by a magnetoresistive metal film. Sensor acts as resistor which resistance

depends on magnetic field strength and direction. This bridge element is capable of

sensing fields in milligauss range.

In order to achieve the measurement resolution, a magnetic pulse must frequently reset

the sensor. Eliminating and compensating external disturbances will be done via coil

strip near of sensor elements with current pulse.

Offset coil strap is used for production level testing and self-testing.

Main features

• Two magnetometer channel blocks (containing X- and Y-axes).

-Measurement with 4-element Wheastone bridge /axes

-Convert magnetic earth field X and Y components to differential outputs

• Set / Reset coil element

-Current pulse to coil for set and reset sensor

• Offset strap coil

-For testing purposes