System and method for the detection and compensation of radio signal time of arrival errors
First Claim
1. A system for the correction of multipath errors in a telecommunication device location system, the system comprising:
- a receiver to receive data transmitted from a remote transmitter located at an unknown distance from the receiver; and
an analyzer to analyze data associated with the received data and to generate location data related to a location of the receiver, the analyzer further calculating a correction factor based on a measured signal criterion to generate corrected location data;
wherein the receiver generates a correlation pulse when the received data is correlated to a stored data pattern, the signal criterion being a pulse width of the correlation pulse;
wherein the signal analyzer models the correlation pulse as a quadratic equation having a plurality of coefficients, the coefficients being determined by amplitude values of the correlation pulse at predetermined times.
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Abstract
A system and method are disclosed by which the effects of time of arrival errors may be reduced. In a mobile unit, such as a CDMA device, a correlation pulse is generated when a transmitted code matches a stored reference code. In the absence of multipath effects, correlation pulses are generated in response to the detection of multiple transmissions of the reference code from multiple transmitters. However, multipath effects distort the generated correlation pulses leading to errors in the time of arrival measurements. The present invention calculates the width of the correlation pulses and determines a delay correction factor based on the pulse width. The delay correction factor is added to the measured delay time to provide a more accurate delay time, thus permitting more accurate location measurements based on time of arrival. In alternative embodiments, other signal factors may also be used to apply delay correction factors. The actual location determination may be performed by the mobile unit, or any other positioning determining entity (PDE). The system is also capable of applying correction factors to time of arrival signals received from global positioning system (GPS) satellites.
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Citations
12 Claims
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1. A system for the correction of multipath errors in a telecommunication device location system, the system comprising:
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a receiver to receive data transmitted from a remote transmitter located at an unknown distance from the receiver; and
an analyzer to analyze data associated with the received data and to generate location data related to a location of the receiver, the analyzer further calculating a correction factor based on a measured signal criterion to generate corrected location data;
wherein the receiver generates a correlation pulse when the received data is correlated to a stored data pattern, the signal criterion being a pulse width of the correlation pulse;
wherein the signal analyzer models the correlation pulse as a quadratic equation having a plurality of coefficients, the coefficients being determined by amplitude values of the correlation pulse at predetermined times. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. The system of claim further comprising a data structure to store a mathematical function relating signal criteria to correction factors wherein the analyzer calculates the correction factor using the selected criteria and the mathematical function.
Specification