Direction sensor
This magnetic sensor employs two perpendicularly intersecting internal coils with a centrally located MR (magnetic resistance) element to sense geomagnetism (a magnetic force traversing Earth in the north/south direction) and use it to determine directions. An MR element is a resistance element whose resistance characteristically changes depending on the strength of the magnetic force. It is structured such that its sensing power varies with the geomagnetic angle.

The MR element employed by the direction sensor is insufficient, because the geomagnetism is weak and the directivity complicated. Two sets of coils have consequently been adopted to divide the components into a more rational, right-angled, two-directional intersection. When the MR element detects the various components, a microprocessor processes the voltage signals received as the resistance changes and determines the direction.

Pressure sensor
The pressure sensor employs the "piezo effect" of the resistance change occurring when four diffusion resistances arranged on a silicon base are distorted to measure pressure.

Outside pressure on the silicon base depresses the surface because of its flexibility and its internal vacuum structure. The diffusion resistance expands in accordance with the movement of the base and the changes in resistance. Since this diffusion resistance is included in the circuit through which a fixed electric current passes, a voltage difference occurs before and after the resistance. Atmospheric pressure and water pressure are computed by digitizing this voltage difference with the A/D converter and processing it by microprocessor.*

* The microprocessor incorporates data on the International Standard Atmosphere (ISA) defined by the International Civil Aviation Organization (ICAO). It compares this with the atmospheric pressure information collected to make high-level conversions instantaneously.