Patent ID: 7630432

Claim:
A method for identifying obstacles in a transmission channel by means of propagation-delay measurement through analysis of a discrete channel impulse response (I k (n)) of the transmission channel using a time-discrete adaptive equalizer connected in series to the transmission channel, the method comprising: determining IIR filter coefficients (a n ) of a recursive filter portion of the time-discrete adaptive equalizer and FIR filter coefficients (b n ) of a non-recursive filter portion of the time-discrete adaptive equalizer; assigning the IIR filter coefficients (a n ) to a first input vector (A(n)) correspondingly, wherein a first vector element (A(n=0)) of the first input vector (A(n)) is pre-assigned with a value of 1 and remaining vector elements (A(n≠0)) of the first input vector (A(n)) are pre-assigned with zeros; assigning the FIR filter coefficients (b n ) to a second input vector (B(n)) correspondingly, wherein vector elements of the second input vector (B(n)) are pre-assigned with zeros; determining a first output vector (A′(n)) from the first input vector (A(n)) and a second output vector (B′(n)) from the second input vector (B(n)) using a discrete Fourier transformation; forming a discrete channel transmission function (H k (n)) by dividing the first output vector (A′(n)) by the second output vector (B′(n)); determining the discrete channel impulse response (I k (n)) from the discrete channel transmission function (H k (n)) using an inverse discrete Fourier transformation; determining local maxima of the discrete channel impulse response (I k (n)) according to locations in time; and converting the locations in time of the local maxima into corresponding distances of the obstacles relative to a position of a measurement receiver containing the time-discrete adaptive equalizer by multiplication by a transmission rate.