ULTRASONIC-MICROWAVE DOPPLER INTRUSION ALARM SYSTEM

• US 3,801,978 A
• Filed: 07/20/1972
• Issued: 04/02/1974
• Est. Priority Date: 07/20/1972
• Status: Expired due to Term

• Current Assignee: Alex Y. Lee, David N. Gershberg
• Original Assignee: Alex Y. Lee, David N. Gershberg
• Inventors: Gershberg, David N., Lee, Alex Y.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Curtis, Marshall M.
• Application Number:
  US05/273,596
• Time in Patent Office: 621 Days
• Field of Search: 340/258C,258D,258A,258R,409,411 343/7ED,7A,5PD,17.7
• US Class Current: 340/516
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 13/862 Combination of radar systems with sonar systems
• CPC Class Codes: G08B 13/1645 using ultrasonic detection means and other detection means, e.g. microwave or infrared radiation
• CPC Class Codes: G08B 13/2494 by interference with electro-magnetic field distribution combined with other electrical sensor means, e.g. microwave detectors combined with other sensor means

Abstract

Motion within a large specified volume is detected by multiple ultrasonic transducer assemblies with a redundant microwave antenna to reduce false alarms. Each of the ultrasonic transducer assemblies contains a plurality of highly directive transmitting radiating elements and/or a plurality of highly directive receiving elements. Combining networks interconnect the various radiating elements in parallel to a frequency source. The microwave transducer includes a transmit/receive antenna coupled to a microstrip oscillator through a microstrip balanced mixer. Signals from the ultrasonic transducers are processed by means of time integration to provide an alarm signal. Similarly, signals received at the microwave antenna are processed by means of time integration to provide an alarm signal. Alarm signals from both the ultrasonic subsystem and the microwave subsystem are combined in logic that responds to generate a system alarm only upon the simultaneous existence of alarm signals from both sources. Also coupled to the ultrasonic subsystem and the microwave subsystem is an automatic self-testing and tamper determining system. When either transducer source indicates a fault condition, an alarm signal is generated by combining logic networks.

Claims

1. An ultrasonic-microwave intrusion system including an alarm for producing an indication of movement within a specified area, the combination comprising:

an ultrasonic detector responsive to movement within the specified area and providing an output signal varying with such movement, a microwave detector responsive to movement within the specified area and providing an output signal varying with such movement, combining circuit means connected to said ultrasonic detector and said microwave detector for generating a signal to the alarm when the output of said detectors simultaneously exists at a level indicating movement within the specified area, and a test circuit connected to said ultrasonic detector and microwave detector and responsive to fault conditions in said detectors to generate a fault indication signal to the alarm.

2. An ultrasonic-microwave intrusion system as set forth in claim 1 wherein said ultrasonic detector includes:

a transmitting transducer for radiating into the specified area radio frequency energy, receiving elements responsive to the radiated energy reflected from a moving body within the specified area and generating a doppler frequency signal, circuit means actuated by the doppler frequency signal to generate the sensor output reflecting movement with the specified area, a frequency generatoR connected to said transmitting transducer means, and a fault responsive circuit providing a fault indication signal upon a failure in the transmitting elements.

3. An ultrasonic-microwave intrusion system as set forth in claim 2 wherein said transmitting transducer includes:

a plurality of bandpass filters having one of a plurality of radiating elements as a part thereof for emitting radiation into the specified area, a plurality of resistive elements individually in series with one of the plurality of bandpass filters, and circuit means for connecting said plurality of bandpass filters and series resistive elements in parallel to said frequency generator.

4. An ultrasonic-microwave intrusion system as set forth in claim 2 wherein said frequency generator includes an R.C. driven operational amplifier, and a radiating element coupled to one terminal of the operational amplifier to lock the frequency output of said generator to the frequency-temperature characteristics of said radiating element, said radiating element is also employed as a transmitting element in the overall system.

5. An ultrasonic-microwave intrusion system as set forth in claim 4 wherein said frequency generator further includes a complimentary symmetry power output switch coupled to the output of said operational amplifier.

6. An ultrasonic-microwave intrusion system as set forth in claim 1 wherein said microwave detector includes:

a monostatic radiating element emitting microwave energy into the specified area and responsive to reflected energy from a moving body, an oscillator for providing a carrier frequency signal, a balanced mixer connected to said radiating element and said oscillator for demodulating a reflected signal received by said radiating element with the output of said oscillator, doppler amplifier means receiving a signal from the balanced mixer for amplification thereof, integrator means connected to the output of said doppler amplifier and integrating the output thereof with respect to time, and a level detector receiving the signal from said integrator and producing an alarm signal when the integrator output exceeds a preset level.

7. An ultrasonic-microwave intrusion system as set forth in claim 6 wherein said balanced mixer includes:

an RF impedance inverter having one end tied to said radiating element and the other end to the output of said oscillator, a first peak voltage detector at the radiating element end of said RF impedance inverter for sampling the RF voltage magnitude at the radiating element, a second peak voltage detector at the oscillator end of said RF impedance inverter for sampling RF voltage magnitude at said oscillator, and means for combining the energy sampled by each of the peak voltage detectors into a balanced mixer output signal for applying to an input of said doppler amplifier.

8. An ultrasonic-microwave intrusion system as set forth in claim 7 including an RF choke coupled to said transmission line at the radiating element end thereof.

9. An ultrasonic-microwave intrusion system as set forth in claim 8 wherein said balanced mixer further includes a D.C. level sampling connection for generating a fault condition signal to said test circuit means.

10. An ultrasonic-microwave intrusion system including an alarm for producing an indication of movement within a specified area, the combination comprising:

transmitting transducers for radiating into the specified area ultrasonic energy, receiving transducers responsive to the radiated energy reflected from a moving body within the specified area and generating a doppler frequency signal, circuit means actuated by the doppler frequency signal to generate a signal reflecting movement within the specified area, a frequency generator connected to said transmitting transducers, a fault responsive circuit providing a fault indication signal upon a failure in the transmitting traNsducers, a monostatic radiating element emitting microwave energy into the specified area and receiving reflections from the moving body within the area and providing an output signal varying with such movement, an oscillator, a balanced mixer connected to said radiating element and said oscillator for combining a signal from said radiating element with the output of said oscillator, doppler amplifier means receiving a signal from said balanced mixer for amplification thereof, integrator means connected to the output of said doppler amplifier means for integrating the output thereof, a level detector receiving the signal from said integrator and providing an alarm signal when the integrator output exceeds a present level, combining means connected to said circuit means and said level detector for generating a signal to the system alarm when the output of said circuit means and said detector simultaneously exists at a level indicating movement within the specified area, and test circuit means connected to said frequency generator and said balanced mixer and responsive to fault conditions therein to generate a fault indication signal to the system alarm.

11. An ultrasonic-microwave intrusion system as set forth in claim 10 wherein said transmitting transducers include:

a plurality of bandpass filters having one of a plurality of radiating elements as a part thereof for emitting radiation into the specified area, a plurality of resistive elements individually in series with one of the plurality of bandpass filters, and circuit means for connecting said plurality of bandpass filters and series resistive elements in parallel to said frequency generator.

12. An ultrasonic-microwave intrusion system as set forth in claim 11 wherein said fault responsive circuit includes:

a peak voltage detector having a diode connected to the common connection of said resistive elements, and an output capacitor interconnected to one electrode of said diode and the output of said frequency generator.

13. An ultrasonic-microwave intrusion system as set forth in claim 11 wherein said frequency generator includes an R.C. driven operational amplifier, and a radiating element coupled to one terminal of the operational amplifier to lock the frequency output of said frequency generator to the frequency-temperature characteristics of said radiating element.

14. An ultrasonic-microwave intrusion system as set forth in claim 10 wherein said balanced mixer includes:

an RF impedance inverter having one end tied to said monostatic radiating element and the other end to the output of said oscillator, a first peak voltage detector at the radiating element end of said impedance inverter for sampling the energy at the radiating element, a second peak voltage detector at the oscillator end of said impedance inverter responsive to energy at said oscillator, and means for combining the energy sampled by each of the peak voltage detectors into a balanced mixer output signal.

15. An ultrasonic-microwave intrusion system as set forth in claim 14 including an R.F. choke coupled to the radiating element end of said transmission line.

16. An ultrasonic-microwave intrusion system as set forth in claim 15 wherein said balanced mixer further includes a D.C. level sampling connection for generating a fault condition signal to said test circuit means.

17. In an intrusion alarm system wherein an ultrasonic detector and a microwave detector each generate a signal varying with movement within a specified area, said detector signals combined in circuit means for providing an alarm when the detector signals simultaneously exists at a level indicating movement within the specified area, wherein the microwave detector comprises in combination:

a monostatic radiating element for emitting microwave frequency energy into the specified area and responsive to such energy reflected from a moving body within such area, an oscillator for generating the frequency signals radiated by said radiating element, a balanced mixer connected to said radiating element and the output of said oscillator for combining a signal from said element with the output of said oscillator, doppler amplifier means receiving a frequency signal from said balanced mixer for amplification thereform, integrator means connected to the output of said doppler amplifier means and integrating the output thereof with respect to time, and level detector means receiving the signal from said integrator and producing an alarm when the integrator output exceeds a preset level.

18. In an intrusion alarm system as set forth in claim 17 wherein said balanced mixer includes:

an RF impedance inverter having one end tied to said radiating element and the other end to the output of said oscillator, a first peak voltage detector at the radiating element end of said impedance inverter for sampling the energy at the radiating element, a second peak voltage detector at the oscillator end of said impedance inverter responsive to energy at said oscillator, and means for combining the energy sampled by each of the peak voltage detectors into a balanced mixer output signal.

19. In an intrusion alarm system as set forth in claim 18 wherein said balanced mixer further includes an RF choke coupled to the radiating element end of said transmission line.

20. In an intrusion alarm system as set forth in claim 19 wherein said balanced mixer further includes a D.C. level sampling connection for generating a fault condition signal to a test circuit.

21. In an intrusion alarm system wherein an ultrasonic detector and a microwave detector each generate a signal varying with movement within a specified area, said detector signals combined in circuit means for providing an alarm when the detector signals simultaneously exist at a level indicating movement within the specified area, wherein said ultrasonic detector comprises in combination:

transmitting transducer elements for radiating into the specified area ultrasonic energy, receiving transducer elements responsive to the radiated energy reflected from a moving body within the specified area and generating a doppler frequency signal, circuit means actuated by the doppler frequency signal to generate the sensor output signal reflecting movement within the specified area, a frequency generator connected to said transmitting transducer elements, and a fault responsive circuit providing a fault indication signal upon a failure in the transmitting antenna.

22. In an intrusion alarm system as set forth in claim 21 wherein said frequency generator includes an R.C. driven operational amplifier, and a radiating element coupled to one terminal of the operational amplifier to lock the frequency output of said generator to the frequency-temperature characteristics of said radiating element.

23. In an intrusion alarm system as set forth in claim 21 wherein said transmitting transducer elements include:

a plurality of bandpass filters having one of a plurality of radiating elements as a part thereof for emitting radiation into the specified area, a plurality of resistive elements individually in series with one of the plurality of bandpass filters, and circuit means for connecting said plurality of bandpass filters in series with said resistive elements in parallel to said frequency generator.

24. In an intrusion alarm system as set forth in claim 23 wherein said fault responsive circuit includes:

a peak voltage detector having a diode connected to the common connection of said resistive elements, and an output capacitor interconnected to one electrode of said diode and the output of the frequency generator.