04728959 is referenced by 224 patents and cites 11 patents.

The present invention combines the relative insensitivity of the phase angle differences of a radio signal to the signal distortions inherent in an urban environment with digital signal processing techniques to produce an accurate and economical way to locate a mobile transmitter station such as a mobile telephone in a cellular telephone network. Phase angle measurements indicative of the angle of direction of a mobile transmitter station from each of a plurality of land stations are obtained by translated Hilbert transformation and are processed to produce a probability density function. The probability density functions are combined after a CHI-squared analysis to produce an area of uncertainty representing the position of the mobile transmitter station. The radio frequency signals emitted from the mobile transmitter station need have no special characteristic for the localization process. Thus, the present invention may easily work as an adjunct to an unrelated communications system such as a cellular telephone system.

Title
Direction finding localization system
Application Number
6/894867
Publication Number
4728959
Application Date
August 8, 1986
Publication Date
March 1, 1988
Inventor
Charles N Katz
Rancho Santa Fe
CA, US
John E Maloney
Springfield
VA, US
Agent
Bacon & Thomas
Assignee
Ventana Sciences
CA, US
IPC
G01S 5/04
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