Patent ID: 6492944
Filing Date: 2002-12-10
Classification: G01S,H04W,Y02D

Abstract:
An internal calibration method for calibrating a first receiver system, wherein said first receiver system is characterized by a time- and frequency-varying transfer function, said transfer function defining how the amplitude and phase of a received signal will be altered by said first receiver system, and wherein the first receiver system is utilized in a location system that is operative to determine the location of a mobile transmitter by, in part, determining a difference in time of arrival of a signal transmitted by a mobile transmitter and received by said first receiver system and another receiver system, and wherein the accuracy of the location determination is dependent, in part, upon the accuracy of time measurements made by said receiver systems, the method comprising the steps of:(A) injecting an internally generated stable, known signal into said first receiver system; (B) utilizing the internally generated stable, known signal to obtain an estimate of the manner in which said transfer function varies across the bandwidth of said first receiver system; and (C) utilizing said estimate to mitigate the effects of said variation of the first transfer function on the time measurements made by the first receiver system.