| 摘要 |
PURPOSE:To decrease the probability of production of error of quantization at low frequencies, by splitting an audio signal into a plurality of bands and quantizing each band with a sampling frequency corresponding to the band. CONSTITUTION:An audio signal Si in e.g., 20-2,000Hz is divided into 20-632Hz and 632Hz-2,000Hz at filters 60, 61, and they are sampled at 1,400Hz and 4,000Hz to obtain quantized signals SA, SB. The signals SA, SB are alternately A/D-converted at a signal processing circuit 62, a serial digital signal SD is obtained and it is transmitted. The transmitted signal is split into a digital signal of each band at a signal processing circuit 64 and converted into analog signals S'A, S'B. They are added to a signal synthesis circuit 67 via filters 65, 66 to obtain an original analog signal SO. |
