SONIC PRESENCE DETECTOR SYSTEM

• US 3,675,190 A
• Filed: 05/19/1969
• Issued: 07/04/1972
• Est. Priority Date: 03/31/1965
• Status: Expired due to Term

• Current Assignee: Jerry P. Huffman, John H. Auer Jr
• Original Assignee: Jerry P. Huffman, John H. Auer Jr
• Inventors: Auer, John H. Jr., Huffman, Jerry P.
• Primary Examiner(s): Bennett, Jr., Rodney D.
• Assistant Examiner(s): Potenza, J. M.
• Application Number:
  US04/836,191
• Time in Patent Office: 1,142 Days
• Field of Search: 340/38,1
• US Class Current: 367/93
• CPC Class Codes: G01S 1/72 using ultrasonic, sonic or infrasonic waves
• CPC Class Codes: G01S 15/04 Systems determining presence of a target
• CPC Class Codes: G01S 15/18 wherein range gates are used
• CPC Class Codes: G01S 7/527 Extracting wanted echo signals Doppler systems G01S15/50
• CPC Class Codes: G01S 7/529 Gain of receiver varied automatically during pulse-recurrence period for seismic signals G01V1/245
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors
• CPC Class Codes: Y10S 367/903 Transmit-receive circuitry

Abstract

A system for indicating the presence of objects, where sonic energy reflected from the surfaces of objects is recognized and detected. Sonic energy pulses are periodically directed toward objects to be detected and electrical signals are generated in response to that portion of the sonic energy reflected from the object'"'"''"'"'s surface. The signals are conducted to a tuned amplifier gated at intervals corresponding to the anticipated transit times of reflected pulses. Recognition circuitry responds to reflected pulses and produces an indication of object presence when they are coincident with the gate intervals. A timer extinguishes the presence indication when reflected pulses cease to be received for a period of time commensurate with a predetermined minimum rate.

Claims

1. An object presence detection system comprising in combination, a. transmitter means producing periodic pulses of sonic frequency and peculiar characteristic, b. transducer means converting said pulses to emitted sonic energy pulses and respondingly generating electrical signals relative to received sonic energy including energy reflected from said object, c. means generating a periodic gate signal for a selected interval between successive sonic energy pulses, d. recognition means operably controlled by said gate signal to be actuateable during said selected interval only by said electrical signals having a characteristic correlative to said peculiar characteristic, and e. detection means rendered operable by actuation of said recognition means to manifest a distinctive indication of object presence for as long as said recognition means is actuated at a greater than minimum rate.

2. The system of claim 3 wherein said peculiar characteristic is a peculiar duration.

3. The system of claim 4 wherein said recognition means includes means generating a signal only in response to any of said electrical signals having a duration exceeding a predetermined minimum for actuating said recognition means.

4. The system of claim 3 wherein said recognition means includes amplifier means in which the gain is raised from a first level to a second level during each said selected interval for making the system relatively insensitive to weak said electrical signals at the beginning of said selected interval.

5. The invention of claim 3 wherein said recognition means includes isolator means biased to substantially attenuate said electrical signals exceeding a predetermined amplitude while conducting said electrical signals of less than said predetermined amplitude relatively unattenuated for limiting said electrical signals not normally characteristic of sonic energy reflected from said object.

6. The system of claim 3 wherein the duration of said selected interval is chAnged inversely to ambient temperature.

7. An object presence detection system comprising in combination, a. transmitter means producing periodic pulses of sonic frequency and peculiar time duration, b. transducer means converting said pulses to emitted sonic energy pulses and respondingly generating electrical signals relative to received sonic energy including energy reflected from said object, c. means generating a periodic gate signal for a selected interval between successive sonic energy pulses, said selected interval varying in duration inversely to ambient temperature, d. recognition means operably controlled by said gate signal to be actuated no more than once during each said selected interval by said electrical signals including, i. isolator means biased to substantially attenuate said electrical signals exceeding a predetermined amplitude while conducting said electrical signals of less than said predetermined amplitude relatively unattenuated for limiting said electrical signals not normally characteristic of sonic energy reflected from said object, ii. amplifier means which gain is raised from a first level to a second level during each said selected interval for making the system relatively insensitive to weak said electrical signals at the beginning of said selected interval and from said second level to a third level whenever object presence is manifested for rendering the system responsive to weaker electrical signals than would normally be required to actuate said recognition means, iii. means generating a signal in response only to any said electrical signal having a duration exceeding a predetermined minimum for actuating said recognition means, and e. detection means rendered operable by actuation of said recognition means to manifest a distinctive indication of object presence for as long as said recognition means is actuated at greater than a minimum rate.

8. An object presence detection system comprising in combination, a. means for periodically emitting pulses of sonic energy and respondingly generating signals relative to energy reflected from said object, b. means generating a periodic gate signal for a selected interval between successive sonic energy pulses, c. amplifier means periodically rendered responsive to said electrical signals by said gate signal wherein the gain is raised from a first level to a second level during each said selected interval so as to make the system relatively insensitive to weak said electrical signals at the beginning of said selected intervals, d. recognition means operably controlled by said gate signal to be actuateable during said selected interval by said electrical signals, and e. detection means rendered operable by actuation of said recognition means to manifest a distinctive indication of object presence.

9. The system of claim 8 wherein said amplifier means includes means for controlling said amplifier gain to rise from said first level at the commencement of each said selected interval to a second level, to rise to a third level for the remainder of said selected interval whenever said detection means manifests a distinctive indication of object presence, and to be at said first level for all other times so as to make the system relatively insensitive to weak said electrical signals at the beginning of said selected intervals and to reductions in the strength of said electrical signals after indication of object presence.

10. In an object detection system wherein transducer means having a first and second output terminal emits periodic sonic pulses and respondingly generates signals relative to reflections of said energy from said object for initiating an indication of object presence, a switching network for limiting said signals not normally characteristic of signals relative to reflected energy from said object by attenuating said signals greater than a predetermined threshold amplitude and conducting said signals less Than said threshold amplitude relatively unattenuated, comprising, center tapped coupling impedance means capable of passing direct current, a first diode connecting between said first output terminal of said transducer means and one end of said impedance means, a second diode with the same conducting polarity as said first diode connecting between said second output terminal of said transducer means and the other end of said impedance means, series resistors arrayed across said signal source, and bias means disposed between the junction of said resistors and said impedance center tap in such manner as to cause said first and second diodes to alternately cut off whenever the applied signal exceeds a threshold amplitude.

11. A method for detecting the presence of objects comprising, a. periodically emitting pulses of sonic energy having a peculiar pulse duration characteristic, b. respondingly generating signals relative to received sonic energy including sonic energy reflected from said objects, c. generating a periodic gate signal for a selected interval between successive sonic energy pulses, d. recognizing only said signals having attributes correlative to said peculiar pulse duration characteristics during said selected intervals, and e. establishing a distinctive indication of object presence whenever said signals having such correlative attributes are recognized during a predetermined span of time governed by said gate signal.