ANTI-INTERFERENCE MICROWAVE MOTION SENSOR

• US 20090160698A1
• Filed: 12/20/2007
• Published: 06/25/2009
• Est. Priority Date: 12/20/2007
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Wu, Xiaodong, Helland, James N., Green, Leslie K.
• Granted Patent: US 7,852,257 B2
• Time in Patent Office: Days
• US Class Current: 342/28
• CPC Class Codes: G01S 13/222 using random or pseudorandom pulse repetition frequency
• 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 7/023 Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36
• CPC Class Codes: G01S 7/0235 Avoidance by time multiplex
• CPC Class Codes: G08B 13/2491 Intrusion detection systems, i.e. where the body of an intruder causes the interference with the electromagnetic field
• CPC Class Codes: G08B 29/24 Self-calibration, e.g. compensating for environmental drift or ageing of components

Abstract

A microwave motion sensor for protecting an area comprises an oscillator configured to generate a plurality of microwave signals, a random pulse generator configured to set a random pulse period for each transmitted microwave signal, an antenna configured to transmit the microwave signals and to receive reflected signals, and a signal processor coupled to the antenna through other circuitry, said signal processor is configured to process the reflected signals to determine a presence of a moving object in the protected area.

Claims

1. A microwave motion sensor comprising:

an oscillator configured to generate a plurality of pulsed microwave signals;

a random pulse generator configured to set a random pulse period for the generated microwave signals;

an antenna configured to transmit the microwave signals and to receive reflected signals; and

a signal processor coupled to the antenna and the random pulse generator and configured to process the reflected signals to determine a presence of a moving object in a protected area.

2. The microwave sensor of claim 1, further comprising a mixer coupled to the antenna and the oscillator and configured to mix the reflected signals received from the antenna with the microwave signals from the oscillator to generate corresponding mixed signals.

3. The microwave sensor of claim 2, wherein the signal processor is configured to process the mixed signal to determine the presence of a moving object in the protected area.

4. The microwave sensor of claim 1, further comprising a coupler configured to couple the antenna to the oscillator and the mixer.

5. The microwave sensor of claim 1, wherein the signal processor is further configured to generate an alarm based on the presence of a moving object in a protected area.

6. The microwave sensor of claim 1, further comprising a signal conditioning circuitry coupled to the mixer and the signal processor and configured to condition the mixed signal.

7. The microwave sensor of claim 6, wherein the signal conditioning circuitry is configured to receive a gating signal from the random pulse generator.

8. A security system for detecting a presence of a moving object in a protected area, the security system comprising:

at least two microwave sensors located in the protected area, the microwave sensors being positioned so that there is interference between signals generated by two or more of the sensors;

each microwave sensor comprising;

an oscillator configured to generate a plurality of microwave signals;

a random pulse generator configured to set a random pulse period for each transmitted microwave signals and to provide a gating signal to a signal conditioning circuitry;

an antenna configured to transmit the microwave signals and to receive reflected signals; and

a signal processor coupled to the antenna and the random pulse generator and configured to process the reflected signals to determine a presence of a moving object in the protected area.

9. The security system of claim 8, wherein each microwave sensor further comprises a mixer coupled to the antenna and the oscillator and configured to mix the reflected signals with the microwave signals to generate corresponding mixed signals.

10. The security system of claim 8, wherein the microwave sensor further comprises a coupler configured to couple the antenna to the oscillator and the mixer.

11. The security system of claim 8, further comprising a signal conditioning circuitry coupled to the mixer and the signal processor and configured to receive a gating signal from the random pulse generator.

12. The security system of claim 8, further comprising an alarm coupled to each microwave sensor, wherein the microwave sensor is configured to trigger the alarm based on the presence of a moving object in the protected area.

13. The security system of claim 8, wherein at least two microwave sensors are positioned adjacent to each other.

14. The security system of claim 8, wherein at least two microwave sensors are positioned facing each other.

15. A method for detecting a presence of a moving object in a protected area, the method comprising:

generating a plurality of microwave signals;

setting a random pulse period for each transmitted microwave signal;

transmitting the plurality of microwave signals;

receiving a plurality of reflected signals; and

processing the reflected signals to determine of a moving in the protected area.

16. The method of claim 15, further comprising mixing the reflected signals with a generated microwave signal to generate a corresponding mixed signal, and processing the mixed signal to determine a presence of the moving object in the protected area.

17. The method of claim 16, further comprising conditioning the mixed signal prior to the processing step.

18. The method of claim 15, further comprising generating an alarm based on a presence of a moving object in the protected area.

19. The method of claim 17, wherein the random pulse period is set by a random pulse generator, the random pulse generator applying a gating signal for controlling the conditioning of the mixed signal.