Patent ID: 7323985

Claim:
An electronic warning system, comprising: an electrical line of a fence extending along a protected area; a pulser; a transmitter for transmitting pulses through said line; a receiver for receiving said pulses after being transmitted along at least a portion of said line; an impedance having a resistance substantially identical to the line characteristic resistance and connected at the end of said line, for absorbing said pulses when said pulses are received thereby at the end of said line so that said pulses do not return to said receiver; a plurality of sensors disposed at spaced-apart locations along said line and actuated responsive to phenomenon occurring in the vicinity thereof, for, when actuated, causing said pulses to return to said receiver; a processor for operating said transmitter and receiver and for actuating a warning signal upon the detection, by at least one of said sensors, of said phenomenon, said processor including means for determining the time taken by a said pulse to return to said receiver in response to the actuation of a said sensor so as to determine the location of the actuated sensor and thus determine the location at which the phenomenon occurred; characterized in that said processor further includes means for presetting and determining the number of pulses received during a preset period of time from receipt of a first pulse, resulting from an occurrence and repeated occurrences of said phenomenon at the same location, and for actuating a warning signal beyond said number of pulses.