PURPOSE: To reproduce the waveform approximately and reduce the memory capacity, by analyzing the analogue waveform by the linear forecasting method to store the forecast coefficient.

CONSTITUTION: The analogue time series waveform is input to analysis display device 2, and device 2 analyzes it and displays the result on CRT 3 and X-Y plotter 4. In this case, a linear forecast coefficient is obtained by analyzer 11 in device 2 and is stored in memory 12, and synthesizer 13 is used to reconstitute the waveform, thus reproducing the input waveform faithfully.