Direction finding localization system
DCFirst Claim
1. A localization system for determining the position of a mobile radio transmitter station using a network of interconnected land stations having known locations, comprising:
- an antenna array configuration at at least two land stations for receiving radio frequency (RF) signals emitted from the mobile radio transmitter station, said configuration comprising at least one pair of antenna elements, each antenna element positioned to transform the RF signal into a corresponding RF electrical signal;
means for measuring a direction angle of the mobile radio transmitter station from at least two land stations by phase difference measurement, including means for performing a phase sensitive weighted integration of a complex conjugate product of an equivalent analytic signal wave form of the RF electrical signal in each antenna element; and
means for processing said direction angle measurements from said at least two land stations to determine a location for the mobile radio transmitter
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Abstract
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.
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Citations
9 Claims
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1. A localization system for determining the position of a mobile radio transmitter station using a network of interconnected land stations having known locations, comprising:
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an antenna array configuration at at least two land stations for receiving radio frequency (RF) signals emitted from the mobile radio transmitter station, said configuration comprising at least one pair of antenna elements, each antenna element positioned to transform the RF signal into a corresponding RF electrical signal; means for measuring a direction angle of the mobile radio transmitter station from at least two land stations by phase difference measurement, including means for performing a phase sensitive weighted integration of a complex conjugate product of an equivalent analytic signal wave form of the RF electrical signal in each antenna element; and means for processing said direction angle measurements from said at least two land stations to determine a location for the mobile radio transmitter - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of locating a mobile radio transmitter station using a network of interconnected land stations having known locations, comprising the steps of:
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receiving radio frequency (RF) signals at at least two land stations that are emitted from the mobile radio transmitter station, said configuration comprising at least one pair of antenna elements, each antenna element positioned to transform the RF signal into a corresponding RF electrical signal; measuring a direction angle of the mobile radio transmitter station from at least two land stations by performing a phase difference measurement, including the step of integrating a phase sensitive weighting function having a complex conjugate product of an equivalent analytic signal wave form of the RF electrical signal in each antenna element; and processing said direction angle measurements from said at least two land stations to determine a location for the mobile radio transmitter station. - View Dependent Claims (8, 9)
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Specification