Electronic compass with direction signal compensation - employs common software in manual and automatic modes using maxima and minima of orthogonal pick=up voltages

摘要

A flux-gate magnetometer (30) having a high-permeability toroidal core, and two outer pick-up windings (32A,32B) inclined at 45 deg. to the direction of travel, is driven (35,37) by a microprocessor (50) which processes signals from wideband amplifiers (39A,39B), synchronous demodulators (41A,41B) and comparators (42A,42B). Feedback is applied to the two pick-up windings (32A,32B) via PWM digital-to-analogue converters (44A,44B). Alphanumeric, analogue and mechanical indicators (58-60) are driven by separate outputs (55-57). USE/ADVANTAGE - In vehicles ranging over extensive territories where geomagnetic North deviates widely from true North. Highly accurate compensation is achievable without need to drive deliberately around circular route.