Multiplexing of a bandpass filter circuit to work with a flux-gate sensor output

Claim 1

A multiplexed control circuit for an electronic compass including a microcomputer, a flux-gate, a flux-gate driver, a bandpass filter, a synchronous detector, an integrator, a summing amplifier, and a ranging circuit the multiplexed control circuit comprising: a gate switch connected at its input to the flux-gate for each magnetic component to be measured; a switching network, controlled by the microcomputer; the gate switches commonly connected at their outputs to the serial connection of the bandpass filter, synchronous detector, integrator and summing amplifier; the microcomputer sending signals to the switching network such that the gate switches for each magnetic component are controlled, alternately conducting, thereby alternately allowing the output of the flux-gate to pass through to the serial connection of the bandpass filter, synchronous detector, integrator and summing amplifier whereby the effects of gain and component tolerances on the control circuit is minimized.