To prevent generation of an echo due to cell conversion from voice information by providing a tapped delay line filter generating a simulated echo from voice information at a remote end and an adaptive filter generating a simulated echo from voice information received by one-preceding cell.
Voice data at a remote end are defined to be Rin(0), Rin(1),... in the order of time series, then a remote end side input cell processing circuit section 200 repeats its processing every time a cell reaches and stores the remote end side voice data in the order of time series. A near end side input cell processing circuit 300 checks a header of a cell to check an error such as a missing cell or mis-allocated cell and and stores voice data from a payload of the cell when no error is found out and stores dummy data produced by a predetermined procedure s voice data when any error is in existence. Since voice data are received synchronously by a simulated echo generating section 100 because of the provision of the circuit sections 200, 300, the operation of the generating section is surely executed to prevent malfunction.
MIZUNO TOSHIRO
FUJITANI HIROSHI
MIURA KAZUMA
NIPPON TELEGRAPH & TELEPHONE