초록 ▼

An improved method and apparatus for automatically monitoring objects, such as vehicles, for example, wherein signpost units are positioned at predetermined locations and each signpost unit transmits a binary signpost code for reception via units installed in the objects being monitored and the obje

An improved method and apparatus for automatically monitoring objects, such as vehicles, for example, wherein signpost units are positioned at predetermined locations and each signpost unit transmits a binary signpost code for reception via units installed in the objects being monitored and the objects being monitored receive the signpost codes and store object location information. In one aspect, the present invention contemplates a method and an apparatus which has a multi-mode operation capability wherein the location of the monitored objects is reported when the monitored object enters a different coverage region in an automatic reporting mode, wherein only those monitored objects within a predetermined region or on a predetermined route report to the base station in a region or route reporting mode, and wherein only the locations of predetermined monitored objects are reported to the base station in a polling mode. In another aspect, the present invention contemplates an improved method and an apparatus for locating and operating the signpost units to reduce the total number of signpost units required to cover a given number of locations wherein each signpost unit establishes a uniquely identifiable near-field region and a uniquely identifiable far-field region, the signpost units being located to establish uniquely identifiable overlap regions wherein a portion of the far-field region of at least one of the signpost units overlaps a portion of the far-field region on another signpost unit. The method and apparatus of the present invention also provides a non-polling location technique eliminating the necessity of interrogating the monitored objects at regular intervals and reducing the radio channel time required for reporting object location.

대표청구항 ▼

Apparatus for use in monitoring objects within a predetermined monitored area comprising: a signpost unit positioned within the monitored area and having a predetermined signpost code encoded therein uniquely identifying the signpost unit and providing an output signal encoded with the signpost code

Apparatus for use in monitoring objects within a predetermined monitored area comprising: a signpost unit positioned within the monitored area and having a predetermined signpost code encoded therein uniquely identifying the signpost unit and providing an output signal encoded with the signpost code, the signpost unit output signal establishing a near field region extending a distance generally from the signpost unit and encompassing a predetermined coverage region at least large enough to encompass a monitored object and the signpost unit output signal establishing a far-field region extending a distance generally from the signpost unit and encompassing a predetermined coverage region, the far-field region extending a distance from the signpost unit greater than the distance of the near-field region from the signpost unit and the strength of the signpost unit output signal within the near-field region being greater than the strength of the signpost unit output signal within the far-field region; and means in the monitored object receiving the signpost unit output signal having a portion detecting the strength of the received signpost unit output signal for providing one output signal in response to a received signpost unit output signal having a signal strength less than a predetermined signal strength level thereby indicating the location of the monitored object within the far-field region of the signpost unit identified via the signpost code encoded in the received signpost unit output signal, and providing another output signal in response to a received signpost unit output signal having a signal strength greater than the predetermined signal strength level thereby indicating the location of the monitored object within the near-field region of the signpost unit identified via the signpost code encoded in the received signpost unit output signal, the means in the monitored object defined further as comprising: a receiver for receiving the signpost unit output signal and providing a receiver output signal encoded with the signpost code encoded in the received signpost unit output signal; a power level detector receiving the receiver output signal and providing a power level signal in one state in response to a received receiver output signal having a signal strength indicating a received signpost unit output signal having a signal strength corresponding to the strength of the signpost unit output signal in the far-field region thereby indicating the location of the monitored object within the far-field region of the signpost unit and providing a power level signal in another state in response to a received receiver output signal having a signal strength indicating a received signpost unit output signal having a signal strength corresponding to the strength of the signpost unit output signal within the near-field region thereby indicating the location of the monitored object within the near-field region; a decoder receiving the receiver output signal and providing the signpost code encoded in the received receiver output signal via a decoder output signal, the decoder receiving the power level signal provided via the power level detector and providing the received power level signal along with the signpost code via the decoder output signal, the state of the power level signal indicating the location of the monitored object within the near-field region of the signpost unit identified via the signpost code encoded in the receiver output signal in one state of the power level signal and indicating the location of the monitored object within the far-field region of the signpost unit identified via the signpost code encoded in the receiver output in one other state of the power level signal; a storage unit receiving the signpost codes and accompanying power level signals from the decoder and storing the received signpost code and accompanying power level signal in one condition of the storage unit, the storage unit providing the signpost code and accompanying power level signal therein in one other condition of the storage unit in response to receiving a signal; a comparison logic network receiving the signpost code and accompanying power level signal provided via the decoder and the signpost code and accompanying power level signal provided via the storage unit, the comparison logic network comparing the signpost code and accompanying power level signal received from the decoder with the signpost code and accompanying power level signal received from the storage unit and providing an output signal in response to the signpost code and accompanying power level signal received from the decoder being identical to the signpost code and accompanying power level signal received from the storage unit, and the comparison logic network providing another output signal in response to the signpost code and accompanying power level signal received from the decoder being different from the signpost code and accompanying power level signal received from the storage unit; a location encoder receiving the signpost code and accompanying power level signal from the storage unit; and means in the monitored object providing the signal for conditioning the storage unit to provide the signpost code and accompanying power level signal for storing in the location encoder in response to a signal from the comparison logic network indicating a difference between the signpost code and accompanying power level signal received from the decoder and the signpost code and accompanying power level signal received from the storage unit.