Method and apparatus for detecting intrusion and non-intrusion events

• US 6,631,096 B2
• Filed: 02/02/2001
• Issued: 10/07/2003
• Est. Priority Date: 02/02/2001
• Status: Expired due to Fees

• Current Assignee: TRW Inc. (Northrop Grumman Corporation)
• Original Assignee: TRW Inc. (Northrop Grumman Corporation)
• Inventors: Progovac, Dusan V., Cooper, Stephen R. W., Gillis, Edward J.
• Primary Examiner(s): MULLEN, THOMAS J
• Application Number:
  US09/776,276
• Publication Number:
  US 20020105417A1
• Time in Patent Office: 977 Days
• Field of Search: 367/93, 367/94, 340/426, 340/539, 340/552, 340/554
• US Class Current: 367/93
• CPC Class Codes: B60R 25/1009 Sonic sensors; Signal treatment therefor

Abstract

An intrusion detection system that differentiates between a vehicle intrusion event and a non-intrusion event includes transmitter (16) for transmitting a continuous wave signal that is reflected of surfaces within the vehicle'"'"'s interior and/or a moving object (i.e., an intruder). The associated reflected signals subsequently return to a receiver (18). An ECU (26) demodulates the return signal into frequency and amplitude components. The ECU (26) further determines a waveform envelope of the demodulated return signals and monitors the envelope waveform during time windows to determine whether their corresponding envelope waveform is indicative of an intrusion event or an non-intrusion event. When an intrusion event is detected, the ECU (26) outputs a control signal to actuate an alarm (34).

Claims

1. An apparatus for detecting an intrusion event within limits of a predetermined area, said apparatus comprising:

a transmitter transmitting a continuous wave signal within the predetermined area;

a receiver receiving reflected return signals from the continuous wave signal;

a demodulator demodulating the return signals;

a monitor monitoring envelopes of the demodulated return signals during time windows; and

a discriminator discriminating between an intrusion and a non-intrusion event in response to the monitored envelopes during the time windows, said discriminator determining a non-intrusion event in response to a predetermined increase and decrease of one of the monitored envelopes during the time windows and determining an intrusion event in response to a predetermined increase of one of the monitored envelopes during the time windows.

2. An apparatus for detecting an intrusion event within limits of a predetermined area, said apparatus comprising:

a transmitter transmitting a continuous wave signal within the predetermined area;

a receiver receiving reflected return signals from the continuous wave signal;

a demodulator demodulating the return signals;

a monitor monitoring waveform envelopes of the demodulated return signals at a sample rate;

a discriminator discriminating between an intrusion and a non-intrusion event in response to the monitored waveform envelopes, said discriminator including;

(a) first determining means for determining a non-intrusion event when the value of the waveform envelope during a first predetermined time window is less than a first predetermined threshold,

(b) second determining means for determining an intrusion event when a predetermined number of samples of the waveform envelope during a second predetermined time window is greater than a second predetermined threshold, and

(c) third determining means for determining a non-intrusion event when said predetermined number of samples of the waveform envelope during said second predetermined time window is less than said second predetermined threshold.

3. The apparatus as set forth in claim 2, wherein said monitor includes means for rectifying said return signal and determining a derivative of the rectified return signal.

4. The apparatus as set forth in claim 3, wherein said discriminator includes closing means for closing said first time window in response to at least one of:

(a) the derivative of the rectified return signal has a zero crossing from positive to negative, and

(b) the number of samples within said first time window has reached a preset value.

5. The apparatus as set forth in claim 3, wherein said discriminator includes timing means for opening said second predetermined time window in response to at least one of:

(a) a predetermined number of samples of the rectified return signal being greater than said second predetermined threshold and outputting a signal indicative of an intrusion event, and

(b) a predetermined number of samples of the rectified return signal is less than said second predetermined threshold and outputting a signal indicative of a non-intrusion event.

6. An apparatus for detecting intrusion within limits of a predetermined area, said apparatus comprising:

transmitting means for transmitting a continuous wave signal within the predetermined area;

receiving means for receiving returns of the continuous wave signal reflected within the limits of the predetermined area;

return signal outputting means operatively connected to said transmitting and receiving means for outputting a demodulated return signal in response to the transmission of said continuous wave signal and the return of said continuous wave signal;

monitoring means for monitoring envelopes of the demodulated return signal at a sample rate, said monitoring means includes means for rectifying said return signal and determining a derivative of the rectified return signal; and

discriminating means for discriminating between an intrusion and a non-intrusion event, said discriminating means including

(1) determining means for determining whether the envelope of the rectified return signal exceeds a set threshold,

(2) first timing means for opening a first time window for performing said monitoring of samples of said envelope, said discriminating means determining whether the non-intrusion event occurred during said first time window and outputting a signal indicative thereof,

(3) closing means for closing said first time window in response to at least one of;

(a) the derivative of the rectified return signal has a zero crossing from positive to negative, and

(b) the number of samples within said first time window has reached a preset value,

(4) second timing means for opening a second time window for further performing said monitoring of samples of said envelope, said discriminating means determining at least one of;

(a) a predetermined number of samples of the rectified return signal is greater than a decay threshold and outputting a signal indicative of an intrusion event, and

(b) a predetermined number of samples of the rectified return signal is less than the decay threshold and outputting a signal indicative of a non-intrusion event.

7. The apparatus as set forth in claim 6, further including enabling means for enabling an alarm in response to a determined intrusion event.

8. The apparatus as set forth in claim 6, further including resetting means for resetting said discriminating means when an intrusion event is determined and at least one of:

(1) the determination of an intrusion event has occurred for a predetermined time period, and

(2) the value of the rectified return signal is less than a predetermined value.

9. The apparatus as set forth in claim 6, further including resetting means for resetting said discriminating means when a non-intrusion event is determined and at least one of:

(1) the rectified return signal is less than the set threshold,

(2) a current sample of the rectified return signal is equal to a preceding sample of the rectified return signal,

(3) a preset time has expired from the time a non-intrusion event is determined,

(4) a preset time has expired from the opening of the second time window, and

(5) the derivative of the rectified output signal is greater than the slope of the derivative of the rectified return output signal.

10. A method for detecting intrusion within limits of a predetermined area, said method comprising the steps of:

transmitting a continuous wave signal within the predetermined area;

receiving returns of the continuous wave signal bounced within the limits of the predetermined area;

demodulating the return signal;

monitoring envelopes of the demodulated return signals during time windows; and

discriminating between an intrusion and a non-intrusion event in response to the monitored envelopes during the time windows, including determining a non-intrusion event in response to a predetermined increase and decrease of one of the monitored envelopes during the time windows and determining an intrusion event in response to a predetermined increase of one of the monitored envelopes during the time windows.

11. A method for detecting intrusion within limits of a predetermined area, said method comprising the steps of:

transmitting a continuous wave signal within the predetermined area;

receiving returns of the continuous wave signal reflected within the limits of the predetermined area;

demodulating the return signal;

monitoring envelopes of the demodulated return signal at a sample rate; and

discriminating between an intrusion and a non-intrusion event including,

(a) determining a non-intrusion event when the value of the waveform envelope during a first predetermined time window is less than a first predetermined threshold,

(b) determining an intrusion event when a predetermined number of samples of the waveform envelope during a second predetermined time window is greater than a second predetermined threshold, and

(c) determining a non-intrusion event when said predetermined number of samples of the waveform envelope during said second predetermined time window is less than said second predetermined threshold.

12. The method as set forth in claim 11, wherein said step of monitoring further includes the steps of rectifying the return signal and differentiating the rectified return signal.

13. The method as set forth in claim 12, wherein said discriminating step further includes the step of closing said first time window when the derivative of the rectified return signal has a zero crossing from positive to negative and when the number of samples within said first time window has reached a preset value.

14. The method as set forth in claim 12, wherein said step of opening said second time window further includes the step of determining at least one of a predetermined number of samples of the rectified return signal is greater than said threshold, and outputting a signal indicative of an intrusion event, and a predetermined number of samples of the rectified return signal is less than said threshold, and outputting a signal indicative of a non-intrusion event.

15. A method for detecting intrusion within limits of a predetermined area, said method comprising the steps of:

transmitting a continuous wave signal within the predetermined area;

receiving returns of the continuous wave signal reflected within the limits of the predetermined area;

outputting a demodulated return signal in response to the transmission of said continuous wave signal and the return of said continuous wave signal;

monitoring envelopes of the demodulated return signal at a sample rate, said monitoring step including rectifying the return signal and differentiating the rectified return signal; and

discriminating between an intrusion and a non-intrusion event, including,

(1) determining whether the envelope of the rectified signal exceeds a set threshold,

(2) opening a first time window for monitoring of samples of said envelope, said discriminating step determining whether the non-intrusion event occurred during said first time window,

(3) closing said first time window when the derivative of the rectified return signal has a zero crossing from positive to negative and when the number of samples within said first time window has reached a preset value,

(4) opening a second time window for monitoring of samples of said envelope, said discriminating step determining when at least one of a predetermined number of samples of the rectified return signal is greater than a decay threshold, and outputting a signal indicative of an intrusion event, and a predetermined number of samples of the rectified return signal is less than the decay threshold, and outputting a signal indicative of a non-intrusion event.

16. The method as set forth in claim 15, further including the step of enabling an alarm upon determination of an intrusion event.

17. The method as set forth in claim 15, further including the step of resetting said discriminating step upon determining an intrusion event and the occurrence of at least one of the on-time of an alarm indicative of an intrusion event is equal to a predetermined time, and the rectified return signal is less than a predetermined value.

18. The method as set forth in claim 15, further including the step of resetting said discriminating step upon determining a non-intrusion event and the occurrence of at least one of the rectified return signal is less than the set threshold, a current sample of the rectified return signal is equal to a preceding sample of the rectified return signal, a preset time has expired from the time the non-intrusion event is determined, a preset time has expired from the opening of the second time window, and the derivative of the rectified output signal is greater than the slope of the derivative of the rectified return output signal.