초록 ▼

A security system senses intrusions into a shipping container through the opening of doors, cutting an opening, or removing the doors from their hinges. Intrusion information is transmitted to a remote receiver without interrogation, thereby reducing power consumption. Sensing is accomplished by em

A security system senses intrusions into a shipping container through the opening of doors, cutting an opening, or removing the doors from their hinges. Intrusion information is transmitted to a remote receiver without interrogation, thereby reducing power consumption. Sensing is accomplished by employing a range-gated micro-impulse radar ("RGR") that generates microwave pulses that bounce around the interior of the container. The RGR includes a range gate that enables measuring reflected signals during the time gate period that is set for the time it takes a pulse to propagate a maximum distance within the container and reflect back. A direct current signal level is produced that represents the average reflected signal level within the container, and a Doppler shift measurement is made that represents motion inside the container. The signals are conveyed to the transmitter for conveyance to the remote receiver.

대표청구항 ▼

We claim: 1. A container security system, comprising: a micro-impulse radar positioned inside the container for transmitting microwave signals and receiving reflections of microwave signals; and a detector operative during a predetermined time period for generating a first signal indicative of an a

We claim: 1. A container security system, comprising: a micro-impulse radar positioned inside the container for transmitting microwave signals and receiving reflections of microwave signals; and a detector operative during a predetermined time period for generating a first signal indicative of an average energy level of the reflections of the signals during the predetermined time period and for generating a second signal indicative of a Doppler shift occurring between the microwave signals and the reflections of the microwave signals during the predetermined time period. 2. The system of claim 1, in which the predetermined time period includes a time required for the emitted microwave signals to propagate from the micro-impulse radar to a most distant point within the container and return to the detector. 3. The system of claim 1, in which the container further includes a door and the first signal includes a level shift indicative of at least one of an open, closed, or removed condition of the container door, a hole in the container, and a change in contents of the container. 4. The system of claim 1, in which the container further includes a door and the second signal includes a Doppler shift indicative of at least one of a movement of the container door, creating a hole in the container, moving a contents of the container, a vibration of the container, and a movement by a human being within the container. 5. The system of claim 4, further including a processor for determining an amount of at least one of the first and second signals and producing an alarm condition based on a comparison to the amount. 6. The system of claim 1, further including a transmitter for communicating information to a remote receiver, the information including information associated with at least one of the first and second signals. 7. The system of claim 6, in which the container further includes a door and a sensor for detecting a status of the door, and the information further includes at least one of whether the door is open and a time period when the door is open. 8. The system of claim 6, in which the transmitter includes a long-range, wireless modem. 9. The system of claim 1, in which the microwave signals are pulses of microwave energy at a frequency of 960 MHz or higher and at a pulse repetition frequency ranging from about 50 kHz to about 500 kHz. 10. The system of claim 9, in which the pulses have a duration of about 10 nsec. 11. The system of claim 1, further including at least one battery for powering the system, and a controller that reduces a current consumption of the radar by activating the radar for a first time period and deactivating the radar for a second time period that is longer than the first time period. 12. The system of claim 11, further including a motion sensor mechanically coupled to the container and electrically coupled to the controller for activating the radar in response to a motion of the container. 13. The system of claim 12, in which the controller senses no significant change in the first and second signals and responds by deactivating the radar. 14. The system of claim 12, further including: at least one container door having an associated door sensor for determining a status of the door; and a transmitter for conveying container intrusion data to a remote receiver, the controller activating the transmitter during a repetitious pattern of low duty cycle time periods or in response a signal generated by at least one of the door sensor, the motion sensor, and the radar. 15. The system of claim 14, in which the controller further includes a time stamp generator and an intrusion counter, and in which the intrusion data includes a total number of container intrusions, a time stamp representing a current time of the intrusion data, and a time stamp for each of a predetermined number of prior intrusions. 16. The system of claim 1, further including a GPS receiver for generating container location information and a transmitter for communicating data to a remote receiver, the data including information associated with at least one of the first signal, the second signal, and the container location information. 17. A method of determining a security of a shipping container, comprising: transmitting microwave signals inside the container and receiving reflections of the microwave signals inside the container; generating a first signal indicative of an average energy level of the reflections of the signals; generating a second signal indicative of a Doppler shift occurring between the microwave signals and the reflections of the microwave signals; and processing at least one of the first and second signals to determine whether a container intrusion has occurred. 18. The method of claim 17, further including communicating to a remote checkpoint information associated with at least one of the first and second signals. 19. The method of claim 17, further including activating the transmitting for a first time period and deactivating the transmitting for a second time period that is longer than the first time period. 20. The method of claim 17, further including mechanically coupling a motion sensor to the container and activating the transmitting in response to a motion of the container. 21. The method of claim 20, further including deactivating the transmitting in response to a cessation of the motion of the container. 22. The method of claim 20, in which the container further includes a door and the method further includes sensing a status of the door, and transmitting container intrusion data to a remote checkpoint in response at least one of the door status, the motion, the first signal, and the second signal. 23. The method of claim 22, in which the intrusion data includes a total number of container intrusions, a current time of the intrusion data, and a time of each of a predetermined number of prior intrusions. 24. The method of claim 23, in which the current time and the time of each of the prior intrusions is a relative time. 25. The method of claim 23, further including sensing container global location information and the intrusion data further includes a container global location associated with the intrusion information and with each of the prior intrusions.