| 摘要 |
<p>A voice signal is input to a drive signal generating unit, an estimating filter and an estimating parameter calculation circuit. The estimating parameter calculation circuit calculates a predetermined number of estimating parameters (α parameters or k parameters) by the self-correlation method or the covariance method, and supplies the calculated estimating parameters to an estimating parameter encoder circuit. The codes of the estimating parameters are supplied to a decoder circuit and a multiplexer. The decoder circuit inputs decoded values of the codes of estimating parameters to the estimating filter and the drive signal generating unit. The estimating filter calculates an estimated residue signal which is a difference between the input voice signal and the decoded estimating parameter, and sends it to the drive signal generating unit. The drive signal generating unit calculates a pulse spacing and an amplitude for each of a predetermined number of subframes based on the input voice signal, estimated residue signal, and quantized values of the estimating parameters, and encodes them, and supplies them to the multiplexer. The multiplexer combines these codes and the codes of the estimating parameters together and sends it to a transmission line as an output signal of the encoder.</p> |
