DEVICE AND METHOD FOR FILTERING VOICE SIGNAL, HANDSET AND TELEPHONE COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To make remarkable flexibility to be obtained at the time of determining null points having fixed positions with the accuracy dependent on the quality and the articulation required for an output signal by extracting values of poles from a predictive analysis circuit and supplying them to a calculating element and determining values of null points among values of the poles. SOLUTION: An input signal 21 is sampled with a frequency Fe being roughly twice of the highest frequency of an original voice signal and a predictive analysis circuit 23 determines, for example, linear predictive encoding parameters every 160 pieces of samples as its result. Poles of postfilters for generating a signal 22 are supplied to a calculating element 26 by an extraction circuit 25 extracting roots pi of a polynominal A(z). In order to calculate null points, the calculating element 26, at first, classifies the pi in the order of the ascending of frequencies of the range from 0 kHz to about 4 kHz and the sampling frequency at this time exists in the vicinity of the frequency of 8 kHz. Then, poles and null points of the postfilters are determined and the element 26 composes postfilters W(z).