| 摘要 |
PURPOSE:To obtain a quantizer where the effect of low burst is not decreased even with a small input to the quantizer by multiplying a companding coefficient decided by an quantized output to a product between a value subtracting the product between the present quantized step size and a constant from 1 and the said quantized step size. CONSTITUTION:The quantizing circuit 1 applies quantization to an inputted difference value X(n) by a quantized step size DELTA(n) and coding to generate a code word output I(n). A delay circuit (Z<-1>)2 and a coefficient device 3 produce an output M(I(n-1)) by using the code word I(n) and give an input to the multiplier 4. On the other hand, a step size DELTA(n-1) produced by a delay at a delay circuit (Z<-1>)5 is inputted to multipliers 6, 7, an output alpha.DELTA(n-1) is produced and an output (1-alpha.DELTA(n-1)) is produced. A multiplier 4 multiplies an output of the coefficient device 3 and the output of a multiplier 7 and produces an output {M(I(n- 1)).DELTA(n-1).(1-alpha.DELTA(n-1))}. An adder 9 adds a constant DELTA0 to the output of the multiplier 4 and generates an output. |
