公开(公告)号：US4554670A

公开(公告)日：1985-11-19

申请号：US484676

申请日：1983-04-13

申请人： Shinichi Aiko ,  Rikio Maruta ,  Takao Nishitani

发明人： Shinichi Aiko ,  Rikio Maruta ,  Takao Nishitani

IPC分类号： H03M3/04 ,  H04B1/66

CPC分类号： H03M3/042

摘要： An adaptive differential pulse code modulated (ADPCM) transmission system includes a subtractor for providing a difference signal E.sub.j between an input signal X.sub.j and a predicted signal X.sub.j. A coder encodes the difference signal E.sub.j into a coded signal U.sub.j for transmission to a receiver. The signal U.sub.j is also decoded at the transmitter to produce a reproduced error signal E.sub.j. A prediction circuit operates to generate a prediction signal X.sub.j on the basis of the reproduced error signal E.sub.j. The prediction circuit is controlled by a control circuit which operates to detect transmitter instability. A first level detector in the control circuit compares the input signal level against the level of a transmitter produced signal representing the input signal. A second level detector of the control circuit determines when the input signal is below a specified value. Transmitter instability is judged by a decision circuit which determines when the output of the first level detector exceeds a preset value and the output of the second level detector is below another preset value.

摘要翻译： 自适应差分脉冲编码调制（ADPCM）传输系统包括用于在输入信号Xj和预测信号Xj之间提供差分信号Ej的减法器。 编码器将差分信号Ej编码为编码信号Uj以传送到接收机。 在发射机处也对信号Uj进行解码以产生再现的误差信号Ej。 预测电路用于根据再现的误差信号Ej产生预测信号Xj。 预测电路由操作以检测发射机不稳定性的控制电路控制。 控制电路中的第一电平检测器将输入信号电平与表示输入信号的发射机产生信号的电平进行比较。 控制电路的第二电平检测器确定输入信号何时低于规定值。 发射机不稳定性由判定电路判定，判定电路确定第一电平检测器的输出何时超过预设值，第二电平检测器的输出低于另一预定值。

公开(公告)号：US4622537A

公开(公告)日：1986-11-11

申请号：US635032

申请日：1984-07-27

申请人： Shinichi Aiko

发明人： Shinichi Aiko

IPC分类号： H04B14/06 ,  H03M3/04 ,  H03M1/12

CPC分类号： H03M3/042

摘要： In a predictive encoder for encoding an encoder input signal into an encoder output signal and having in a feedback loop an adaptive predictive filter which comprises a plurality of taps assigned with adaptive prediction coefficients and produces a predictive signal predictive of the encoder input signal, an encoder control circuit monitors products between the coefficients and tap signals derived from the taps so as to force each product to zero when an absolute value of each product is not greater than a predetermined value. The feedback loop is temporarily placed in an inactive state when the predictive signal becomes zero as a result of all zeros of the products. A predictive decoder is also operated by the use of a decoder control circuit similar to the encoder control circuit and cooperating with an adaptive predictive filter of the decoder. Each adaptive predictive filter may be either of an FIR type or of an IIR type.

摘要翻译： 在用于将编码器输入信号编码为编码器输出信号并且在反馈环路中具有自适应预测滤波器的预测编码器中，所述自适应预测滤波器包括分配有自适应预测系数的多个抽头并产生预测编码器输入信号的预测信号，编码器 控制电路监视从抽头得到的系数和抽头信号之间的产品，以便当每个产品的绝对值不大于预定值时，迫使每个产品为零。 当预测信号由于产品的全部零而变为零时，反馈回路暂时处于非活动状态。 预测解码器还通过使用类似于编码器控制电路的解码器控制电路并与解码器的自适应预测滤波器配合来操作。 每个自适应预测滤波器可以是FIR类型或IIR型。