Perimeter Security System

• US 20110084833A1
• Filed: 12/17/2010
• Published: 04/14/2011
• Est. Priority Date: 07/12/2006
• Status: Active Grant

• Current Assignee: Bluehalo Labs LLC
• Original Assignee: Intelligent Automation, Inc.
• Inventors: van Doorn, Eric, Rangaswamy, Sendil
• Granted Patent: US 8,232,878 B2
• Time in Patent Office: Days
• US Class Current: 340/539.16
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 7/003 Transmission of data between radar, sonar or lidar systems and remote stations
• CPC Class Codes: G08B 13/126 for a housing, e.g. a box, a safe, or a room
• CPC Class Codes: G08B 13/187 by interference of a radiation field
• CPC Class Codes: G08B 13/2491 Intrusion detection systems, i.e. where the body of an intruder causes the interference with the electromagnetic field

Abstract

A security system for detecting physical intrusion in a monitored area including a plurality of radio units arranged in a network around the monitored area to determine received signal strength and pass variations thereof through the radio units to a base station.

Claims

1. A perimeter security system for detecting physical intrusion in a monitored area comprising

a plurality of narrow-band, low data rate, low power radio units arranged in a network, each of said radio units having a signal transmitter, a signal receiver, a circuit coupled with the receiver to measure the signal strength of signals received by the receiver and produce an output representative of received signal strength, a controller responsive to said circuit output to cause said transmitter to transmit a transmitted signal representative of the strength of the signal received by said receiver and to provide said radio unit with a receive mode and a transmit mode such that said receiver and said transmitter do not operate simultaneously, said radio units being positioned such that each radio unit is within communication range of at least one other radio unit;

and

a base station positioned to receive said transmitted signal from one of said radio units and to provide an indication of intrusion into the monitored area.

2. A perimeter security system for detecting physical intrusion in a monitored area as recited in claim 1 wherein said transmitted signals are frequency hopped.

3. A perimeter security system for detecting physical intrusion in a monitored area as recited in claim 1 wherein each of said radio units includes a memory coupled with said controller for storing radio unit control algorithms for operating said transmitter of each radio unit.

4. A perimeter security system for detecting physical intrusion in a monitored area as recited in claim 1 wherein said circuit establishes a nominal threshold for received signal strength and produces a signal representative of intrusion in the monitored area when the received signal strength exceeds said threshold.

5. A perimeter security system for detecting physical intrusion in a monitored area as recited in claim 4 wherein said nominal threshold is adjusted continually to compensate for environmental changes.

6. A perimeter security system for detecting physical intrusion in a monitored area as recited in claim 1 wherein said radio units are arranged such that alternating radio units have an amplifier and the other radio units do not have an amplifier.

7. A perimeter security system for detecting physical intrusion in a monitored area as recited in claim 1 wherein said radio units are arranged in a triangular pattern.

8. A perimeter security system for detecting physical intrusion in a monitored area as recited in claim 1 wherein said radio units are arranged to form an inner ring and an outer ring around the monitored area.

9. A perimeter security system for detecting physical intrusion in a monitored area as recited in claim 1 wherein said radio units include narrow band, low data rate, low power radios.

10. A perimeter security system for detecting physical intrusion in a monitored area as recited in claim 1 wherein the same transmitted signals from said transmitters of said radio units are used to detect intrusions and to transmit detection status to said base station.

11. A perimeter security system for detecting physical intrusion in a monitored area as recited in claim 10 wherein said transmitted signals from said radio units are packet-based and intrusion detection information is added to the packets transmitted to said plurality of radio units such that intrusion detection information reaches said base station via said plurality of radio units.