JP2587591B

PURPOSE:To decrease the scale and increase the speed by dividing a digital signal of a speech and a musical sound into plural bands through a band-pass filter group, and sampling the respective band digital signals down to a Nyquist rate and then performing adaptive conversion and encoding. CONSTITUTION:The speech and musical sound signal is divided by the low-pass filter 1 and high-pass filter 2 and made into a sampling signal of 8KHz through down samplers 3 and 4, and the signal is stored in buffers 5 and 6 in the form of blocks of 32msec; and ATC encoders 7 and 8 perform the adaptive conversion and encoding. The data signals of the low and high bands and auxiliary information are multiplexed by a multiplexer 11 and sent out to a transmission channel. In the band division encoding, complex arithmetic points of one block are halved in number from 2N=512 at the time of 16KHz sampling to N=256 and the complex arithmetic quantity of one block is therefore halved from Nlog2N to 2X(NX2)log2(N/2).