Techniques for overhead-wire detection

The paper describes three wire detection techniques. A millimetre-wave pulsed radar system operating on the grating returns from wires with a regular mechanical structure is discussed. Experimental evidence at 35 GHz proves the operational philosophy of the system and suggests that higher frequencies would produce more successful results. A passive 50 Hz system operating on the magnetic flux produced by live overhead power cables is shown to be capable of indicating the presence and direction of such wires at ranges in excess of 500 m. Finally, a CO2 pulsed laser radar is discussed together with a processing algorithm to highlight wire presence. It is shown that identification of a 1/8 in diameter wire at 200 m range and in a visibility of 200 m is possible using only 4 W of laser power.