Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2002-05-27
2004-11-16
Wu, Daniel J. (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S901000, C340S902000, C340S903000, C340S904000, C340S906000, C340S988000, C340S436000, C340S691100, C340S691300, C340S691500, C340S435000, C340S572100, C340S572300, C340S572700, C701S045000, C701S117000, C701S301000, C343S760000, C343S878000, C343S894000
Reexamination Certificate
active
06819245
ABSTRACT:
BACKGROUND
Security systems are commonly available to monitor psychiatric patients, assist in confinement of prisoners, and track or discourage unauthorized use of aircraft, boats, cars, trucks, construction equipment, and other mobile high-value items (generally herein, “vehicles”). Relatively elaborate and costly security systems (including vehicle recovery systems) may allow locating and/or tracking such vehicles using satellite navigation systems linked to a terrestrial network and/or through use of a directional antenna to receive omnidirectional transmissions from the tracked vehicle. Still other systems merely provide for disabling a vehicle and/or activation of a local alarm carried by the vehicle (using, e.g., flashing lights, horn or siren). These security systems vary widely in cost and capability. They generally operate independently or as part of a network requiring the payment of fees.
Sophisticated tracking and/or interception systems allow remote determination of vehicle direction which is useful for tracking a vehicle. Examples of such systems are described in U.S. Pat. No. 6,326,903 B1, incorporated herein by reference. Direction references described in the '903 patent include those provided by magnetic compass and by using successive locations determined through GPS satellites. But GPS-based systems are relatively costly and complex, as noted above, and magnetic compasses are subject to significant potential errors due to magnetic declination as well as variable magnetic deviations resulting from magnetic materials and/or magnetic fields in the vicinity of the compass.
Other U.S. patents related to vehicle communications, security, tracking and/or monitoring include U.S. Pat. Nos. 4,818,998; 4,903,279; 4,908,629; 6,191,708; 6,292,724; 6,320,514; 6,320,535; 6,323,566; 6,326,903; 6,327,257; 6,329,901; 6,330,452; 6,331,825; 6,346,877; and 6,353,743, each incorporated herein by reference.
Taken together, the above examples and similar systems offer many useful features, but a single integrated system offering a comprehensive selection of features at a moderate price is not available. Such a system would provide timely, specific and effective security information locally and/or would communicate such information with one or more base stations spaced apart from the vehicle. Capabilities would include provisions for broad area coverage through a plurality of base stations, with coordinated monitoring of individual vehicle movement as well as control of traffic flow comprising one or more vehicles. Specific features underlying these capabilities would include, but not be limited to, means for estimating the location, heading, and speed of each vehicle, and its range from one or more base stations, in near real time.
SUMMARY
The present invention comprises at least one addressable transponder for receiving security information addressed to it from at least one base station, and for transmitting security information to at least one base station. A transponder preferably automatically acknowledges receipt of security information from a base station via a transmission to one or more base stations. Each such acknowledgment transmission comprises at least one transponder address corresponding to the receiving transponder.
Each addressable transponder comprises an addressable transponder receiver, an addressable transponder transmitter connected to the transponder receiver, and a transponder antenna connected to the transponder receiver and the transponder transmitter. Each transponder receiver comprises a discriminator for rejecting base station transmissions not addressed to that transponder, together with a decoder to decode security information encoded in base station transmissions addressed to the transponder. Further, each transponder transmitter comprises an encoder for encoding security information comprising the transponder's address in each transmission from that transponder.
And each transponder antenna comprises a steerable directional antenna and a steerable directional antenna azimuth sensor for providing security information comprising a transponder antenna azimuth indicative of each azimuth to which said steerable directional transponder antenna is steered.
The present invention also comprises at least one base station for receiving security information transmitted from at least one addressable transponder, for transmitting security information addressed to at least one such transponder, and for communicating security information with at least one operator.
Each base station comprises a base station transmitter, a base station receiver connected to the base station transmitter, a base station antenna connected to the base station transmitter and the base station receiver, and an operator interface connected to the base station transmitter and the base station receiver for bidirectional communication with at least one operator of security information (including security commands) received and/or transmitted by each base station.
Each base station receiver comprises a decoder to decode security information encoded in transmissions received from at least one addressable transponder. Further, each base station transmitter comprises an encoder for encoding security information comprising at least one transponder address in each transmission from that base station to at least one addressable transponder. And each base station antenna comprises a steerable directional antenna and a steerable directional antenna azimuth sensor for providing security information comprising a base station antenna azimuth indicative of each azimuth to which said steerable directional base station antenna is steered.
Transponder and base station antenna azimuths can provide valuable security information for locating and/or tracking a vehicle that carries the transponder. Thus, a transponder antenna is preferably mounted on a vehicle so that the transponder antenna azimuth is indicated by the antenna azimuth sensor relative to the vehicle (e.g., preferably relative to the direction of forward travel of the vehicle). A base station receiving a transmission of security information comprising such a transponder antenna azimuth can then estimate the heading of the vehicle in near real time.
Such vehicle heading estimates are made with respect to a (preferably previously established) base station antenna azimuth reference (for example, true north). By knowing both the azimuth of the base station antenna on which security information is received from the vehicle transponder, as well as the transponder antenna azimuth relative to the direction of forward travel of the vehicle, the heading of the vehicle with respect to the base station antenna azimuth reference (e.g., true north) may then be estimated as described herein below.
Heading information can reveal a vehicle's orientation in traffic, and may also be used in conjunction with other security information described herein to predict a future location of the vehicle. These functional capabilities can in turn facilitate control of traffic flow and/or allow the vehicle's interception and recovery. Note that since estimates of the vehicle heading in this example are made relative to the base station azimuth reference, the vehicle itself does not need an azimuth reference other than its own structure (as reflected, for example, in the vehicle's direction of forward travel). In particular, the vehicle does not require access to an external reference such as might be provided by a magnetic compass or GPS receiver.
Thus, use of steerable directional antennas in both base stations and transponders of the present invention provides operational advantages not obtainable in other systems without directional antennas or in systems relying on use of directional antennas at only one end of a vehicle communication link. One such advantage relates to vehicle location. Several well-known techniques for vehicle location rely on triangulation, which may also be employed in the present invention for tracking and/or locating a vehicle
Nguyen Tai Tan
Wu Daniel J.
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