| 摘要 |
PURPOSE:To convert a residual echo into an unintelligible noise by varying the transfer function of an adaptive transversal filter finely at random around a steady value. CONSTITUTION:The transfer function of filter F of echo canceler EC is varied finely at random around a steady value by the output of artificial random signal generator PSD and an residual echo is made random and converted into a white unintelligible noise, Canceler EC consists of adaptive transversal filter TF and correlator CR, and TF of tap low-delay lines T1...Tn, multipliers M1.....Mn+1, and adder SM with the correlator connected to multipliers. After being multiplied by small coefficient K by multiplier ML2, the output of artificial random signal generator PSD is applied to multiplier ML1, where it is multiplied by the output of adder SM of filter TF. The multiplication output and SM and added together by adder ADD2 and its result is inputted to adder ADD, thereby varying finely the transfer function of TF. |
