AC MAGNETIC TRACKING SYSTEM WITH PHASE LOCKING

摘要

Plural transmitter coils (1Ox, 10Y, 10z) of a magnetic locating system are driven with widely- separated main frequencies (fx, f?, fz). One of the transmitter coils is also driven with a marker frequency (f '?) close to the main frequency applied to that coil. The receiver (32) determines a phase relationship with the transmitter based on the main and marker frequencies, so that the receiver does not suffer from phase ambiguity. The main (f?) and marker (f 'y) frequencies may interfere with one another, and the receiver may correct for such interference based on known characteristics of the signals at the main and marker frequencies.