1. An adaptive detection method for quantized signals with a finite number of signal states, said method comprising the steps of receiving a quantized signal, detecting the signal states of the received signal using a set of reference vectors stored in a memory, updating the stored set of reference vectors on the basis of samples of the actual signal states of the received signals, the updating of the reference vectors comprising a) calculating a first corrected set of reference vectors by a method employing a self-organizing map, on the basis of a stored set of reference vectors used in the detection and samples taken from actual received signal states in a predetermined time window, the calculation step comprising the sub-steps of a1) using as the starting point the present stored set of reference vectors used in the detection, a2) collecting a sample set for each reference vector, said sample set containing all the signal samples whose closest reference vector belongs to the set of neighbors of the first corrected set of reference vectors, a3) calculating for each reference vector the average of the collected sample set, a4) forming a first corrected set of reference vectors from said calculating average, of the collected sample sets, a5) repeating sub-steps a2), a3) and a4) for the same sample set with a desired number of iteration cycles using as the starting point in sub-step a2) the first corrected set of reference vectors formed during the previous iteration cycle, b) calculating a second corrected set of reference vectors by utilizing a K-means type method on the basis of the first corrected set of reference vectors and said samples of the actual signal states, c) updating the stored set of reference vectors used in the detection by said second corrected set of reference vectors, d) moving the time window in the time domain for sampling a new sample set from actual signal states of the received signal, and e) repeating process steps a), b), c) and d) for each new time window defined at step d).