초록 ▼

A method for mitigating multipath effects in radio systems which is based on searching for and finding a maximum likelihood estimate of range for a received signal is provided. In determining the maximum likelihood estimate, the correlation process uses a high resolution step method in processing th

A method for mitigating multipath effects in radio systems which is based on searching for and finding a maximum likelihood estimate of range for a received signal is provided. In determining the maximum likelihood estimate, the correlation process uses a high resolution step method in processing the received signal sample values to develop an estimation statistic. The estimation statistic using the correlations of the received signal is based on a new derived representative set of coefficients formed from a nonlinear combination of parameters of the received signal transformed into a linearly solvable invertible parameter set allowing solution of the maximization process of the estimation statistic over a reduced dimension search space. Additionally there is a method of constraining the relative amplitude of received secondary signals to obtain a refinement of the optimal solution of range. The method includes a process to reduce the magnitude of the processing required by the receiver by reducing the size of the overall sample of the signal that must be managed by the receiver. The method may be used in a signal environment where multiple secondary path signals are received by the signal ranging system.

대표청구항 ▼

1. A process for optimally estimating the direct path propagation delay of a received signal when also receiving one or more secondary propagation path signals, the process comprising the steps:A. selecting a direct propagation path signal delay estimate {circumflex over (.tau.)} and a secondary pat

1. A process for optimally estimating the direct path propagation delay of a received signal when also receiving one or more secondary propagation path signals, the process comprising the steps:A. selecting a direct propagation path signal delay estimate {circumflex over (.tau.)} and a secondary path additional propagation delay estimate .DELTA.{circumflex over (.tau.)} as a point ({circumflex over (.tau.)}, .DELTA.{circumflex over (.tau.)}) on a two-dimensional plane; B. computing the value of the cross-correlation [EQU15] where {tilde over (r)}(t) represents the received signal translated to baseband, m(t-{circumflex over (.tau.)}) represents a replica of the signal modulation delayed by {circumflex over (.tau.)}, and [t0,t0+T] is the interval of observation of {tilde over (r)}(t); C. computing the value of the cross-correlation [EQU16] where m(t-({circumflex over (.tau.)}+.DELTA.{circumflex over (.tau.)})) represents a replica of the signal modulation delayed by {circumflex over (.tau.)}+.DELTA.{circumflex over (.tau.)}, and {tilde over (r)}(t) and [t0,t0+T] are as defined in step B; D. Obtaining the value of the zero-delay signal modulation replica autocorrelation [EQU17] and the value of the signal modulation replica autocorrelation [EQU18] at the delay .DELTA.{circumflex over (.tau.)}; E. computing [EQU19] using the values obtained in steps B, C and D, where Re stands for the real part and Im stands for the imaginary part, with .gamma.i=0 and with .alpha.c a maximum value selected for the secondary path signal relative amplitude; F. computing an estimation statistic .LAMBDA.=2Re[(a-jc)R({circumflex over (.tau.)})]+2Re[(b-jd)R({circumflex over (.tau.)}+.DELTA.{circumflex over (.tau.)})]-2(ab+cd)K(.DELTA.{circumflex over (.tau.)})-(a2+b2+c2+d2)K(0) with the values a, b, c, and d obtained from step E; G. assigning the computed estimation statistic A of step F to the point ({circumflex over (.tau.)},.DELTA.{circumflex over (.tau.)}) of step A.