Patent ID: 6636042
Filing Date: 2003-10-21
Classification: G01V

Abstract:
A system for locating underground metal and pipe objects comprising:a) a transmitter for generating a RF signal, b) first connection apparatus for applying the RF signal to the underground object, c) an above ground antenna array of antenna elements for receiving RF signals transmitted by the underground object, d) a commutator for periodically and sequentially receiving signals from each antenna element in the array, the commutator frequency modulating the received signal, e) a frequency modulation detector for demodulating the signal from the commutator and providing a Doppler effect frequency shift in the transmitted signal due to the commutator, f) a vector positional display for indicating position of the object based on Doppler effect frequency shift of the demodulated signal relative to a reference signal, g) second connection apparatus for coupling the demodulated signal and the reference signal to the display, and h) a reference clock for providing the reference signal to the display.