| 摘要 |
PURPOSE:To perform fast quantization without any normalizing circuit by providing a detecting means for the maximum or minimum value of voice data, a means which outputs a threshold level corresponding to the detection data, and a comparing circuit which compares input data with said level. CONSTITUTION:A voice signal converted to a specific amplitude value is outputted from an AGC circuit 2 and digitized by an A/D converting circuit 3. A maximum value calculating part 5 and a minimum value calculating part 6 detects the maximum and minimum for a specific period. Multiplying circuits 9 and 10 multiply the detected values by specific coefficients epsilon1 and epsilon2 and the results are stored in a storage part 12. The stored results are used as threshold levels for compared data by a comparison part 7. The comparison part 7 compares the output of the converting circuit 3 with said threshold levels. The multiplying circuits 9 and 10 perform multiplication by, for example, epsilon1=0.4 and epsilon2=0.4, so the threshold values are proportional to the amplitude value of the input signal. Namely, ternary coding performed by the comparison part is based upon the threshold levels normalized by the maximum and minimum amplitude values. |
