| 摘要 |
PURPOSE:To obtain a stable and highly accurate coder by constituting a denominator of a preset device with the cascade connection of a fixed filter and the 2nd order filter to realize a stable preset device having >=the 3rd preset order. CONSTITUTION:An input signal from an input terminal 1 of a coder is inputted to a quantization device 200 while the signal is subjected to a difference with an adaptive preset device at a difference circuit 100 and quantized and outputted to an output terminal 2. Further, an output of an inverse quantization device 300 applies inverse quantization and the result is inputted to a cascade circuit comprising a noncyclic adaptive filter 10, a cyclic fixed filter 20 and the 2nd order cyclic adaptive filter 30. Outputs of the filters 10-30 are added by an adder 700 and the added output is fed to the difference circuit 100. Then the filters 10-30 and the adder 700 constitute the adaptive preset device, the preset order is taken as the 3rd order or over and the coder is operated stably with high accuracy.
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