Communications: directive radio wave systems and devices (e.g. – Directive – Position indicating
Reexamination Certificate
2003-01-22
2004-08-31
Blum, Theodore M. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Position indicating
C342S465000
Reexamination Certificate
active
06784842
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to location systems based on radio frequency (“RF”) signals, and in particular to such systems that are based on RF signals capable of providing data communications within a facility.
In connection with location systems based on RF signals, particularly if the system is based on time of arrival of RF signals, it is desirable to calibrate the system using sampling of the RF environment at known locations within the facility. Such calibration can provide improved accuracy to the system, and compensate for undesirable effects, such as multi-path reflections and the refraction of radio waves around objects within the facility.
In connection with the calibration of such systems, the initial calibration can be time consuming and require considerable attention of installation employees. Further, facilities such as warehouses and manufacturing plants may have a changing RF environment because of modifications performed within the facility to accommodate changes in production or changes in the goods stored within the facility.
It is an object of the present invention to provide new and improved methods and systems for calibrating location systems based on RF signals, both during the initial installation thereof and when recalibration is necessary or desirable.
SUMMARY OF THE INVENTION
In accordance with the invention there is provided a method for calibrating a location system based on RF signals in a facility. According to the method identification devices are provided at selected locations in the facility. The RF environment is sampled at a plurality of the selected locations. Data representing the sample RF environment and corresponding selected location is signaled to a computer. The computer maintains a database collating the RF environment data and the selected locations, and the computer utilizes the database to calibrate the location system.
In one exemplary embodiment of the present invention, the identification devices are bar code labels which encode their particular selected location. The sampling includes reading the bar code data with a portable bar code reader. This signaling comprises sending the bar code data and the sampled RF environment data from the portable bar code reader via RF data communications. In another exemplary embodiment of the present invention, the identification devices are RFID tags which encode their particular selected location. The sampling includes reading the RFID tag data with a portable RFID tag reader. The signaling comprises sending the RFID tag data and the sampled RF environment data from the portable RFID tag reader via RF data communications. In yet another exemplary arrangement the identification device is an RF communication device for communicating with one or more fixed communication devices in the facility. The RF environment is sampled by sampling transmissions received from the RF communication devices on the identification device. Alternatively, the identification device can perform sampling of the RF environment by sampling transmissions received by the RF communications device of the identification device. Data representing the sample RF environment can be signaled to the computer using the RF communication device on the identification device.
In accordance with the invention there is provided a system for calibrating a location system based on RF signals at the facility. The system includes identification devices placed at selected locations in the facility. A receiver is provided for sampling the RF environment at a plurality of the selected locations in the facility. A computer receives data representing a sample RF environment and the corresponding selected locations in the facility. The computer is programmed to maintain a database corrolating the RF environment data and the selected fixed locations and calibrates the location system using the database.
The identification devices can be bar code labels encoding the selected locations. The receiver is provided on a portable bar code reader, which includes an RF data communications radio and is arranged to send data representing the fixed bar code location and identification data and the RF environmental data to the computer by RF data communications.
In yet another exemplary arrangement, the identification device comprises RF communications device for communicating with one or more fixed communications devices in the facility. Sampling the RF data comprises sampling transmissions received by the identification device from the fixed communications devices. Alternatively the RF communications devices are arranged to sample transmissions received from the identification device. The identification device may be arranged to send data representing the sampled RF environment using the RF communications device therein.
For a better understanding of the present invention, together with other and further objects, reference is made to the following description, taken in conjunction with the accompanying drawings, and its scope will be pointed out in the appended claims.
REFERENCES:
patent: 5977913 (1999-11-01), Christ
“Enhancements to the RADAR User Location and Tracking System” by Bahl et al.;Microsoft ResearchandUniversity of California at San Dieago; pp. 1-13.
“User Location and Tracking in an In-Building Radio Network” by Paramvir Bahl;Microsoft Research, Technical Report, Feb. 1999, pp. 1-12.
Baker & Botts L.L.P.
Blum Theodore M.
Symbol Technologies Inc.
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