| 摘要 |
<p>PURPOSE:To prevent increase of quantizing error when predictive error is large and deterioration of signals at the time of overload inputting by switching and selecting one of plural non-linear quantizing circuits according to the level of predictive error output detected by a level detecting circuit. CONSTITUTION:Predictive data of a predicting device 14 are subtracted from input data signals by a subtractor 11 and sent to a non-linear quantizing device 12, and output data selected by a change-over switch 12S are taken out from an output terminal 16 and sent to a representative value setting section 15. Output data switched and selected by a change-over switch 15S are sent to an adder 13 and added to predictive data from the predicting device 14 and sent to the predicting device 14. Output data of a nonlinear quantizing device 12 are sent to a level detecting switch controlling circuit 18 and switches 12S and 15S are controlled by a switch change controlling circuit 18S according to detected level. Condensing characteristic of non-linear quantizing circuits are set to make the width of quantizing step of the circuit 12a the coarsest and finer from the circuit 12b to 12n, and change-over switches 12S and 15S are switched and controlled successively toward the circuit 12n side when the width of variation of input signals become large.</p> |
