Patent ID: 8103059

Claim:
A method for digital signal processing, comprising: (a) sequentially emitting x signals and receiving the reflected signals; (b) digitizing the reflected signals to corresponding digital signals; (c) accumulating the digital signals to generate an accumulated signal; (d) applying a digital filtering operation to the accumulated signal to generate a filtered signal; (e) finding a maximum signal value for the filtered signal and setting a threshold value according to the accumulated signal; (f) determining whether the maximum signal value is less than the threshold value; and (g) if the maximum signal value is not less than the threshold value, calculating a distance value; wherein the threshold value is represented by a first function f(x), wherein, if x1>x2, f(x1)≧f(x2) then [f(x1)/x1]≦[f(x2)/(x2)].