| 摘要 |
PURPOSE:To improve the talking quality characteristic without increasing the hardware by using an orthogonal mirror filter for band split, band conversion and band synthesis while being installed at the transmission line side. CONSTITUTION:Each frequency band signal only is extracted from a reception input signal Rin by a band filter and converted into a minimum frequency band signal by a resample circuit. The similar processing is applied also to a transmission input signal Sin including an echo component by a band pass filter and a resample circuit to obtain an echo signal is subjected to low frequency conversion. A pseudo echo signal subjected to low frequency conversion similarly from the echo signal subjected to low frequency conversion is subtracted by a subtraction circuit to obtain a residual output from which the echo component is eliminated. The orthogonal mirror filter is used for the part of the band conversion filter to cancel surely the loopback component.
|
