Microwave detection system and method

• US 7,439,876 B2
• Filed: 05/31/2006
• Issued: 10/21/2008
• Est. Priority Date: 08/02/2005
• Status: Active Grant

• Current Assignee: Progress Rail Services Corporation (Caterpillar Incorporated)
• Original Assignee: General Electric Company
• Inventors: Torassa, Paolo, Pieralli, Moreno, Zadeh, Masoud M.
• Primary Examiner(s): Bugg; George A
• Assistant Examiner(s): Hunnings; Travis R
• Application Number:
  US11/421,118
• Publication Number:
  US 20060232440A1
• Time in Patent Office: 874 Days
• Field of Search: 340901-905, 340/928, 340/933, 340/435, 340/436, 340/541, 340/550, 340/552, 340/554, 340/561, 340/565, 340/945, 246/125, 246/122.R, 246/126, 246292-295, 246/473.1
• US Class Current: 340/903
• CPC Class Codes: B61L 29/30 Supervision, e.g. monitoring arrangements
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 13/756 using a signal generator for modifying the reflectivity of the reflector G01S13/758 takes precedence
• CPC Class Codes: G01S 7/4008 of transmitters
• CPC Class Codes: G01S 7/4021 of receivers
• 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 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

A microwave detection system includes a transmitter configured to transmit a signal along a path to detect an intruder to a monitored zone and a modulating reflector configured to receive the transmitted signal to generate a modulated signal having a characteristic introduced by said modulating reflector, the modulating reflector being configured to transmit the modulated signal. The system also includes a receiver located to receive the modulated signal and an adaptive threshold adjustment unit configured for providing a variable detection threshold responsive to a change in a gain of the system. The system further includes a processor configured for processing the modulated signal provided by the receiver and configured for measuring a characteristic in the processed modulated signal with respect to the variable detection threshold provided by the adaptive threshold adjustment unit.

Claims

1. A microwave detection system comprising:

a transmitter configured to transmit a signal along a path to detect an intruder to a monitored zone;

a modulating reflector configured to receive the transmitted signal to generate a modulated signal having a characteristic introduced by said modulating reflector, said modulating reflector configured to transmit the modulated signal;

a receiver located to receive the modulated signal;

an adaptive threshold adjustment unit configured for providing a variable detection threshold responsive to a change in a gain of the system; and

a processor configured for processing the modulated signal provided by the receiver and configured for measuring a characteristic in the processed modulated signal with respect to the variable detection threshold provided by the adaptive threshold adjustment unit.

2. The system of claim 1, further comprising a test modulator configured for injecting a test signal into the receiver to allow determining the gain of the system.

3. The system of claim 2, wherein the processor is further configured for measuring the test signal to determine the gain of the system.

4. The system of claim 3, wherein the processor is further configured for providing a gain measurement signal indicative of the gain of the system to the adaptive threshold adjustment unit.

5. The system of claim 4, wherein the adaptive threshold adjustment unit is further configured for providing a threshold adjustment signal to the processor indicative of the variable detection threshold.

6. The system of claim 5, wherein the processor is further configured for subtracting the variable detection threshold from the received modulated signal when the gain of the system decreases.

7. The system of claim 5, wherein the processor is further configured for adding the variable detection threshold from the received modulated signal when the gain of the system increases.

8. The system of claim 1, wherein the adaptive threshold adjustment unit is further configured for increasing the variable detection threshold when the gain of the system increases.

9. The system of claim 1, wherein the adaptive threshold adjustment unit is further configured for decreasing the variable detection threshold when the gain of the system decreases.

10. The system of claim 1, wherein the monitored zone is an off-limits zone and the system is configured for automatically detecting intrusion in the off-limits zone.

11. The system of claim 1, wherein the monitored zone is a runway of an airport and the system is configured for automatically detecting incursion of an object in the runway.

12. The system of claim 1, wherein the system is configured for automatically tracking ground movements of an object in one or more a monitored zones.

13. A method for automatically detecting intrusion in a monitored zone, said method comprising:

transmitting a microwave signal along a path to detect an intruder to an off-limits zone;

receiving the microwave signal at a modulating reflector;

modulating the signal received by the modulating reflector to generate a modulating signal having a characteristic;

transmitting the modulated signal to be received by a receiver;

adjusting a detection threshold responsive to a gain of the system; and

processing the received modulated signal to measure the characteristic in the received modulated signal with respect to the detection threshold.

14. The method of claim 13, further comprising determining a gain of the system.

15. The method of claim 14, wherein when the determined gain indicates an increased gain compared to a prior determined gain, increasing the detection threshold.

16. The method of claim 14, wherein when the determined gain indicates a decreased gain compared to a prior determined gain, decreasing the detection threshold.

17. The method of claim 14, wherein adjusting a detection threshold responsive to the determined gain comprises subtracting a signal level amount from the received modulated signal corresponding to an increase in gain of the system.

18. The method of claim 14, wherein adjusting a detection threshold responsive to the determined gain comprises adding a signal level amount to the received modulated signal corresponding to a decrease in gain of the system.

19. The method of claim 13, further comprising initiating an action as a function of the measured characteristic with respect to the detection level threshold.

20. The method of claim 19, wherein the action comprises generating an intrusion alarm indicating that an intrusion in the monitored zone has been detected.

21. The method of claim 13, wherein the monitored zone is an off-limits zone.

22. The method of claim 13, wherein the monitored zone is a runway of an airport, the method further comprising automatically detecting incursion of an object in the runway.

23. The method of claim 13, further comprising automatically tracking ground movements of an object in one or more a monitored zones responsive to detection of the object entering or leaving the monitored zone.