| 摘要 |
PURPOSE:To improve a tone quality and to make unnecessary a circuit which obtains a difference by compressing the band of a sound signal from a microphone, and transmitting the signal from a transmission path at a transmission speed 64Kbps. CONSTITUTION:A voice which has been received by a microphone 1 (on a left side) is converted into an electric signal, converted into a digital signal by an A/D 24, sent through an echo canceler 4 to a 32K adaptive differential encoder 3, converted into a code at a sampling frequency 8KHz at four bits, and inputted to a multiplexing part 7. The voice received by a microphone 4 (on a right side) is converted into the electric signal, converted into the digital signal by an A/D 26, and sent through an echo canceler 5 to a 32K adaptive differential encoder 6. Further the signal is converted into the code at the sampling frequency 8KHz at four bits, and inputted to the multiplexing part 7. For this reason, the tone quality is excellent, and since a differential signal is not used, a differential circuit is made unnecessary, and a circuit scale is miniaturized. |
