Active supervision of motion-detection systems

• US 5,093,656 A
• Filed: 03/12/1990
• Issued: 03/03/1992
• Est. Priority Date: 03/12/1990
• Status: Expired due to Term

• Current Assignee: Detection Systems, Inc. (Robert Bosch GmbH)
• Original Assignee: Detection Systems, Inc. (Robert Bosch GmbH)
• Inventors: Dipoala, William S.
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US07/492,482
• Time in Patent Office: 722 Days
• Field of Search: 340/522, 340/516, 340/515, 340/554, 340/567
• US Class Current: 340/522
• 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 7/4052 by simulation of echoes
• CPC Class Codes: G01S 7/4095 the external reference signals being modulated, e.g. rotating a dihedral reflector or modulating a transponder for simulation of a Doppler echo
• CPC Class Codes: G08B 29/02 Monitoring continuously signalling or alarm systems
• CPC Class Codes: G08B 29/183 Single detectors using dual technologies G08B13/1672, G08B13/2448, G08B13/2494 take precedence

Abstract

A microwave motion-detection system incorporates apparatus for actively supervising the operability of the entire microwave system, from the transceiver component, through the output of its signal processing circuitry. Such supervision apparatus comprises a target simulator which responds to a time-varying electrical signal to cause the transceiver to respond as it does when detecting the type of change in reflected microwave energy normally caused by a target of interest moving in the region under surveillance. Preferably, such target simulator comprises a low-cost, general purpose diode positioned in close proximity to the receiver element of the transceiver, a low-frequency signal generator, and timing and control apparatus for periodically applying the output of the signal generator to such diode. In the event of a failure of any microwave system component during the target simulation operation, the supervision apparatus provides a "trouble" alarm. When the microwave system comprises one of the two components of a "dual-technology" motion-detection system, the timing and control apparatus assures a predetermined "quiet time" preceeding each target simulation operation. Such "quiet time" verifies that the microwave motion-detecting component is not continuously "in alarm", as may be caused, e.g., by a noisy receiver diode.

Claims

1. A microwave motion-detection system for detecting the motion of targets in a region under surveillance, said system comprising:

(a) transceiver means for transmitting microwave energy into such region and for receiving such microwave energy upon being reflected by targets within such region, said transceiver means comprising a resonant cavity, a microwave energy-producing element disposed in said cavity, an antenna for directing microwave energy from said cavity toward said region and for concentrating such microwave energy, upon being reflected by targets in said region, to a location within said cavity, and detecting means disposed in said cavity for detecting microwave energy reflected back to said cavity by such targets, said energy-producing element being responsive to an applied electrical signal to produce such microwave energy,

(b) circuit means for detecting any change in frequence between the transmitted and received microwave energy as produced by a target moving within such region and for providing an output signal in response to detecting a predetermined frequency change; and

(c) target-simulating means for simulating the movement of targets in such region, said target-simulating means comprising a general purpose diode arranged to be irradiated by microwave energy produced by said microwave energy-producing element, and signal-generating means for producing a time-varying voltage across said diode, whereby the impedance of said diode to microwave energy is caused to change according to the applied signal, causing the circuit means to respond as though a target had moved within such region.

2. The apparatus as defined by claim 1 wherein said target-simulating means further comprises timing and control means for establishing a first time interval, and for applying said time-varying voltage to said diode for a predetermined time period at a certain time with respect to said first time interval.

3. The apparatus as defined by claim 2 wherein said timing and control means comprises means for establishing a second time interval when said voltage is applied to said diode, means for determining whether said circuit means produces an output signal within said second time interval, and means for providing a supervisory signal in the event said output is not provided within said second time interval.

4. A dual-technology intruder detection system for detecting the presence of an intruder in a region under surveillance, said system comprising:

(a) a microwave component for detecting intruders by transmitting microwave energy into such region and detecting, from the energy reflected from intruders moving within such region, the presence of such intruders;

(b) a passive-infrared component for detecting intruders by monitoring such region for relatively abrupt changes in temperature as produced by intruders moving within such region; and

(c) intruder-simulating means for selectively causing both said microwave and passive-infrared components to respond, within a predetermined time interval, as though an intruder were moving in such region;

said microwave component comprising;

transmitter means for transmitting microwave energy of predetermined frequency into such region; and

receiver means for detecting changes in frequency of such microwave energy upon being reflected by objects moving within such region; and

said intruder-simulating means comprising a general purpose diode positioned in close proximity to said receiver means to be irradiated by microwave energy transmitted by said transmitting means, and circuit means for selectively applying a low frequency signal to said diode, thereby causing said receiver means to respond as though it had detected a change in frequency of such reflected energy.

5. The apparatus as defined by claim 4 wherein said intruder-simulating means further comprises timing and control means for establishing a first time interval, and for applying said time-varying voltage to said diode for a predetermined time period at a certain time with respect to said first time interval.

6. The apparatus as defined by claim 5 wherein said timing and control means comprises means for establishing a second time interval when said voltage is applied to said diode, means for determining whether said circuit means produces an output signal within said second time interval, and means for providing a supervisory signal in the event said output is not provided within said second time interval.

7. A dual-technology intruder detection system for detecting the presence of an intruder in a region under surveillance, said system comprising:

(a) a microwave component for detecting intruders by transmitting microwave energy into such region and detecting, from the energy reflected from intruders moving within such region, the presence of such intruders, said microwave component providing an alarm signal in response to detecting intrusion;

(b) a non-microwave component for detecting intruders by monitoring such region for other changes in ambient conditions caused by the presence of intruders within such region; and

(c) intruder-simulating means for selectively causing both said microwave and non-microwave components to respond as though an intruder were moving in such region;

said microwave component comprising;

transmitter means for transmitting microwave energy of predetermined frequency into such region; and

receiver means for detecting changes in frequency of such microwave energy upon being reflected by objects moving within such region; and

said intruder-simulating means comprising a general purpose diode positioned in close proximity to said receiver means to be irradiated by microwave energy transmitted by said transmitting means, and circuit means for selectively applying a low frequency signal to said diode, thereby causing said receiver means to respond as though it had detected a change in frequency of such reflected energy.

8. The apparatus as defined by claim 7 wherein said intruder-simulating means further comprises timing and control means for determining whether either of said components has detected an intruder within a predetermined time interval preceeding the application of said low frequency signal to said diode.

9. The apparatus as defined by claim 8 wherein said timing and control circuit comprises means for providing an alarm indication in the event the microwave component is substantially continuously providing said alarm signal for an extended period of time.