Acoustic bus passenger counter
First Claim
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.
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Accused Products
Abstract
A system for detecting and counting entry and exit of passengers. Transmitted high frequency sound beams define at least two zones through which passengers pass in sequence when entering or leaving a vehicle; the motion of a passenger through the zones produces signals at a receiver which are fed to logic circuits to produce appropriate counts. The logic circuits discriminate between moving human targets and other moving objects within the zones, and include range discrimination to prevent interference from outside the detection area. In one embodiment the sensor is located above the entry area to detect passengers'"'"' heads, while another embodiment is located at a level to detect passenger foot motion.
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Citations
11 Claims
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1. An automatic passenger counter for vehicles, comprising:
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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 Dependent Claims (2, 3, 4, 5)
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6. An automatic passenger counter for vehicles, comprising:
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acoustic transmitter means for transmitting acoustic signals, said transmitter including pulse generator means and transducer means for generating and transmitting pulsed acoustic signals; acoustic receiver means for receiving acoustic signals returned from passengers entering and leaving the vehicle, said receiver means including transducer means for receiving and converting acoustic signals to corresponding electrical signals, detector means for said electrical signals, and trigger means for converting said received and detected signals to corresponding range pulses; 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 comprising a plurality of zone gates connected in parallel to the output of said trigger means for receiving said range pulses, and timing means for enabling said gates sequentially and for selected time periods whereby each gate will pass range pulses received from targets within corresponding range zones; trigger means responsive to the outputs from said zone gates for producing pulses corresponding to the signals returned from said zones; 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 Dependent Claims (7, 8, 9, 10, 11)
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Specification