Method and apparatus for processing signals for ranging applications

Method for processing at least one signal sent by a transmitter, in use said signal to measure the separation, ie, the distance between said transmitter and a receiver, said signal a modulated carrier signal comprising a code pseudorandom noise (PRN), said method comprising the following steps: - mixing said signal with a replica of the carrier signal, to acquire a baseband signal, representing said PRN code, - multiplying said baseband signal respectively band with at least four replicates (PM, ..., P + N) of the PRN code, said replicas being offset in time with respect to each other, - calculating the correlation values ​​(IM, ..., I + N) of said baseband signal with respect to each of said at least four PRN code replica's, - calculating, from said correlation values ​​(IM, ..., I + N), an estimate of the multipath error, characterized in that said calculation is based on a predefined formula, equating said multipath error to a predefined function of said correlation values ​​(IM, ..., I + N), said predefined formula a linear combination of said correlation values ​​(IM, ..., I + N), wherein each of said normalized values ​​by the correlation value (I0) of said punctual replica (P0), said linear combination as follows: ** (Omitted) ** in which MP represents the multipath error, d represents the spacing of advance-delay, I0 represents the correlation value of said punctual replica, IM, ..., I + N represent the correlation values, .alpha..sub.i represent one or more predefined values, the said values ​​.alpha..sub.i constant being calculated only once during the design of the receiver, and obtaining said one or more predefined values ​​.alpha..sub.i by optimizing so that the resulting estimate multipath is adjusted in the best way the actual multipath error in terms of least squares a wide range of ratios of signal strength / multipath.