Highly accurate odometer

Claim 1

An odometer for accurately measuring long linear lengths, comprising in combination a wheel driving an electric pulse generator, said pulse generator producing a first predetermined number of pulses for each predetermined amount of said wheel rotation, said wheel rotation measuring a predetermined increment of said linear length depending upon the circumference thereof, a pulse shaper, a total pulse counter for indicating said long linear length, a subtotal pulse counter for determining when a second predetermined number of pulses has been reached, means for comparing a preset count representing said second predetermined number of pulses with said subtotal pulse counter, a NAND gate for passing a pulse when said preset count has been reached by said subtotal counter, a selector switch in the input of said total pulse counter, an add channel for introducing an extra pulse, comprising a time-delay circuit for delaying said NAND gate pulse at least the width of one of said shaped pulses, a pulse regenerator, and an OR gate for passing said total number of shaped pulses in addition to said regenerated pulse to an add side of said selector switch, and a subtract channel for removing a pulse, comprising a delay and regeneration means connected to the output of said pulse shaper, an inhibit signal flip-flop having an input connected to receive said NAND gate pulse, and an inhibit OR gate for passing said delay and regeneration means output to a subtract side of said selector switch, except when said inhibit signal is present.