| 摘要 |
PURPOSE:To transmit a high speed voice band data signal by providing a control section having a fixed pole forecast device including a fixed pole forecast filter connected in cascade connection with an adaptive pole forecast filter of an adaptive forecast device and a fixed pole amplitude adaptive control circuit applying adaptive control to the output amplitude of the fixed pole forecast filter. CONSTITUTION:When an input signal S1(K) is a voice signal or a low speed MODEM signal, since the fixed pole amplitude adaptive control circuit 53 is constituted to bring the 1st amplitude adaptive control coefficient alpha(k) to '0'[alpha(k) 0] automatically, a forecast signal alpha(k)S(k) from the amplitude adaptive control coefficient circuit 57 is zero, the fixed pole forecast filter 55 does not forecast the input signal but the adaptive zero forecast filter 19a and the adaptive pole forecast filter 19b apply forecast by the standard system. On the other hand, when a high speed MODEM signal such as 7,200bit/s comes as the input signal, the fixed pole amplitude adaptive control circuit 53 brings the alpha(k) to the unity automatically [alpha(k) 1), and the fixed pole forecast filter 55 applies forecast to the input signal.
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