Magnetometer circuitry for use in bore hole detection of ac magnetic

Abstract

A system for measuring X and Y vector components of a composite magnetic field including static portions such as those produced by the earth's magnetic field, and time varying portions such as those produced by current flowing in a target anomaly to thereby permit determination of the distance and direction from a sensor to the anomaly is disclosed. Highly sensitive fluxgate magnetometers sense total field X and Y axis vector components of the composite magnetic field of interest and produce output signals which are fed through corresponding detector and null circuits to produce total field signals corresponding to the components being measured. These total field component signals are fed through corresponding signal conditioning circuits to equalize the time varying and static field portions of the signal components. Thereafter, the X and Y axis equalized signals are supplied by way of a multiplexer and an analog to digital converter to suitable transmission circuitry which transmits the digital signals via a wireline to a receiver. At the receiver, the signals are decoded and supplied to a computer for deconvolving and for determination of the distance and direction to the anomaly from the sensor.