SIGNAL ANALYSING AND SYNTHESIZING FILTER BANK SYSTEM

摘要

33 "Signal analysing and synthesizing filter bank system" In a signal analysing and synthesizing filter bank system, the analysing bank receives a signal sampled at the rate fe and produces N contiguous subband signals sampled at the rate fe/N. From the subband signals the synthesizing bank must recover the incoming signal. These filter banks are formed by modulation of a prototype filter by sinusoidal signals which, for subband k (0 ? k ? N-1), have a frequency (2k+1)fe/(4N) and respective phases +(2k+1).pi./4 and -(2k+1).pi./4 for the analysing and synthesizing banks. These signals are furthermore delayed by a time delay (Nc - 1)/2fe), where Nc is the number of coefficients of the prototype filter. Preferably, the analysing bank is realized by the cascade arrangement of an N-branch polyphase network (12) and a double-odd discrete cosine transform calculating arrangement (14) and the synthesizing bank is realized by the cascade arrangement of a double-odd discrete cosine transform calculating arrangement (15) and an N-branch polyphase network (17); Fig. 4).