×

Acoustic bus passenger counter

  • US 3,997,866 A
  • Filed: 03/31/1975
  • Issued: 12/14/1976
  • Est. Priority Date: 03/31/1975
  • Status: Expired due to Term
First Claim
Patent Images

1. An automatic passenger counter for vehicles, comprising:

  • acoustic transmitter means including a frequency modulated oscillator and a first transducer, said transducer converting the output of said oscillator to acoustic waves for transmission;

    acoustic receiver means for receiving acoustic waves returned from passengers entering and leaving the vehicle, said receiver means including a second transducer responsive to acoustic waves to produce corresponding output signals, and mixer means responsive to said second transducer output to produce range signals having frequencies proportional to the distances of targets from which transmitted acoustic signals are reflected to said receiver transducer;

    limiting means restricting the response of said receiver to signals returned from defined range zones through which passengers enter and leave the vehicle, said limiting means including a zone filter for each range zone, each zone filter passing only those range signals which are reflected from targets in its corresponding zone;

    circuit means responsive to each zone filter for converting range signals passing through the corresponding filter to output pulses having amplitudes proportional to the speed of motion of the target corresponding to the received range signal and having a polarity dependant on the direction of such motion; and

    logic means responsive to the sequence of said pulses to produce an enter or an exit count signal corresponding to each passenger entering or leaving said vehicle.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×