Patent ID: 7917320

Claim:
A method for optically sensing a remote object using an optical sensing apparatus, said object moving in a zone covered by said apparatus, the method comprising the steps of: (a) angularly scanning the line of sight of said optical sensing apparatus to cover a predetermined zone, (b) sending at least one optical pulse at each predetermined line of sight tilted by an angle θ j relative to a reference direction, (c) receiving for each predetermined line of sight θ j at least one optical signal, (d) converting said optical signals into digital signal waveforms S, each of the said digital signal waveforms being formed of data sampled at a predetermined number N p of range values R i , i=1, 2, 3, . . . , N p , and (e) storing into memory said signal waveforms S(R i , θ j , t k ) acquired for each line of sight θ j and for each acquisition time t k , (f) numerically processing said digital signal waveforms, said numerical processing step comprising: (f1) retrieving from said memory the signal waveforms S acquired for the lines of sight θ j enclosed in an angular subregion delimited by predetermined boundary angles θ REF and θ LIM , so that θ LIM ≦θ j ≦θ REF , (f2) selecting intervals over which the values of the object velocity V, the object direction of travel θ V , the distance of intersection D REF of said object with the reference line of sight θ REF and the time t REF of intersection with said reference line of sight θ REF will be varied, (f3) computing for a first combination of parameters V, θ V , D REF , t REF the time t j at which said object could have intersected a first line of sight θ j enclosed in said angular subregion, and retrieving the signal waveform S(R i , θ j , t k ) acquired at the time t k which is the closest to said computed time t j , (f4) computing for said first combination of parameters V, θ V , D REF , t REF the distance D j from said apparatus at which the object could have intersected said first line of sight θ j , (f5) performing a range shift by the quantity D REF -D j of said signal waveform S(R i , θ j , t k ) retrieved in step (d), (f6) repeating step (f3) to (f5) for each said line of sight θ j enclosed in said angular subregion, (f7) generating a waveform SA by computing the average of the set of signal waveforms that have been range-shifted according to step (g), (f8) repeating steps (f3) to (f7) for each different combination of said parameters V, θ V , D REF , t REF , (f9) finding the specific combination of said parameters V, θ V , D REF , t REF , that gives an averaged signal waveform SA having the maximum signal amplitude, (f10) updating a previous signal waveform having the maximum signal amplitude with the one determined in step (f9), (f11) updating motion parameters of said object with the said combination of parameters V, θ V , D REF , t REF determined in step (f9); wherein the signal to noise ratio of the generated signal waveform generated by the optical sensing apparatus is increased by said numerical processing.