Light vehicle range discriminator

Claim 1

Apparatus for detecting and signaling the intrusion (with respect to a point on the earth) of a light vehicle including means to prevent a signaling of a heavy vehicle intruding upon said point, said apparatus comprising in combination: (a) single geophone means mounted and adapted to respond to vibrations in the ground and to provide an output indicative of vibrations sensed thereby; (b) first means including high-pass means connected to receive the output of said geophone means, said first means further including means for providing an output when the long-term average of high frequency vibrations reaches a predetermined relation to the short-term average thereof; (c) second means including low pass means connected to receive the output of said geophone means, said second means further including means for providing an output when the long-term average of low-frequency vibrations reaches a pedetermined relation to the short-term average thereof; (d) an oscillator means having an output for providing pulses; (e) OR circuit means having three inputs and an output means; (f) counter means having an input and an output; (g) first AND circuit means having a pair of inputs and an output; (h) latch means having an input and an output; (i) means including inverter means for connecting the output of said first means to one of said inputs of said OR circuit means, said other inputs of said OR circuit means being connected to receive: (1) the output of said oscillator means, and (2) an output from said counter means, and said OR circuit output means being connected to the input of said counter means; (j) means including inverter means for connecting the output of said counter means to one of the input means of said first AND circuit means; (k) means connecting the output of said second means to the other of the input means of said first AND circuit means; (l) means connecting the output of said first AND circuit means to the input of said latch means; (m) second AND circuit means having a pair of inputs and an output; (n) means including inverter means connecting the output of said latch means to one of the inputs of said second AND circuit means; (o) third means including low pass means connected to receive the output of said geophone means, said third means further including means for providing an output when the long-term average of low-frequency vibrations reaches a predetermined relation to the short-term average thereof; and (p) means connecting the output of said third means to the other input of said second AND circuit means whereby said apparatus functions as follows: (1) upon the approach of a heavy vehicle toward said point said first and second means signals are connected as aforesaid to thereby cause said latch means to operate to thereby signal the intrusion of a heavy vehicle, the operation of said latch means in turn inhibiting said second AND gate from signal in a vehicle at the output thereof, (2) upon the approach of a light vehicle toward said point, said first and second means function coactively so as to inhibit the operation of said latch means, and said third means functions to produce an output signal which is applied to said other input of said second AND circuit means to thereby produce a signal at the output thereof indicative of the presence of a light vehicle.