Method and apparatus for processing signals for ranging applications

A receiver for ranging applications, said receiver comprising a plurality of channels for detecting and locking onto a plurality of PRN encoded signals, each channel comprising:

• a delay line, comprising M+N+1 taps, M+N+1 being at least four, for obtaining M+N+1 PRN codes, one of which is a punctual code P0, one a first early code P−1, and one a late code P+1, with an early-late spacing d between the early and late code,
• M+N+1 mixers and M+N+1 accumulators to calculate M+N+1 correlation values (I−M, . . . ,I+N),
• a multipath estimator module to calculate a multipath error estimate MP, according to a predefined formula, said formula being a linear combination of said M+N+1 correlation values (I−M, . . . ,I+N), each of said values being normalized by the correlation value I0 of said punctual replica P0,
• a low pass filter.

A method for estimating a ranging error due to multipath in a receiver, said receiver comprising:

• a delay line, comprising M+N+1 taps, M+N+1 being at least four, for obtaining M+N+1 PRN codes, one of which is a punctual code P0, one an early code P−1, and one a late code P+1, with an early-late spacing d between the early and late code,
• M+N+1 mixers and accumulators to calculate M+N+1 correlation values (I−M, . . . , I+N),
• a multipath estimator module to calculate a multipath error estimate (MP), according to the formula:
• MP
• =
• ∑
• i
• =
• -
• M
• ⁢
• ⁢
• …
• ⁢
• ⁢
• N
• ⁢
• ⁢
• α
• i
• ⁢
• 1
• I
• 0
• ⁢
• I
• i
• 1
• -
• 
• i
• 
• ⁢
• d
• 2
• wherein MP represents the multipath error, d represents the early-late spacing, I0 represents the correlation value of said punctual replica, I−M, . . . ,I+N represent the correlation values, αi represent M+N+1 fixed values,
• said method comprising the steps of:
• simulating, for a fixed signal-to-multipath amplitude ratio and for different multipath delays:
• the multipath range error and M+N+1 correlation values,
• using said simulated range errors and correlation values to obtain a system of equations, each equation equating the simulated multipath range error to a linear combination of the M+N+1 correlation values,
• obtaining said αi values by solving said system of equations.