J.C. Patents
Method for canceling echo
A method for canceling echo. A threshold value signal is set to a preset value and the threshold value signal and a medium value signal are keep at a level of the preset value. Diagnosis is made as to whether a difference between an echo signal (I) and the medium value signal (I-1) is more than a positive threshold value or less than a negative threshold value. When the difference between an echo signal (I) and the medium value signal (I-1) is more than the positive threshold value, the level of the medium value signal (I) is increased by an upraise speed and the level of the threshold value signal (I) is increased by a first speed faster than the upraise speed. When the difference between the echo signal (I) and the medium value signal (I-1) is less than the negative threshold value, the level of the medium value signal (I) is decreased by a drop speed and the level of the threshold value signal (I) is decreased by a second speed faster than the drop speed. When the difference between the echo signal (I) and the medium value signal (I-1) is not more than the positive threshold value or not less than the negative threshold value, which represents the level of the echo signal (I) in an normal range without adjusting the threshold value, the symbol (I) represents a present condition of a corresponding signal and the symbol (I-1) represents a previous condition of a corresponding signal.
Winbond Electronics Corp.
H
H04M
inventional
Yueh-Chang
Chen