| 摘要 |
PURPOSE:To improve the coding efficiency and to attain simplicity and miniaturization of a circuit by applying independently high efficiency coding to plural resampling signal at the transmission side, transmitting the coded signal with multiplex, receiving a multiplexed signal at the reception side and decoding the signal into plural resampling decoding signal. CONSTITUTION:An input signal before sampling is expressed in Equation I , where F'(omega) is the frequency, F(omega) is a frequency of a signal f'(t) applied to a terminal 1, Tsec is the sampling interval and omega0 is a sampling frequency. The f'(t) consists of an even order sampling signal f'e(t) and an odd number sampling signal f'0(t) by a signal separation switch 41 and each spectrum is expressed in Equations II and III. When the input signal is a voice signal and it is sectioned at several hundred msec, since the f(t) is regarded as a steady-state signal and the f'e(t) and the f0'(t) are handled as steady-state signals. The f'e(t) and f'0(t) outputted from the signal separation switch 41 are inputted respectively to adaptive differential PCM coding circuits 25, 26, they are corrected into coefficients supplying a good forecast value so long as they are steady-state signals, and the f'e(t) and f'0(t) are coded into codes with good coding efficiency. |
