JPS5668080A - Forecast coding device - Google Patents

Abstract

PURPOSE:To make the real-time processing possible independently of past sample values, by constituting the device by the first loop to generate a forecast signal and a forecast error signal finally and the second loop to subtract a higher forecast signal from the input signal previously. CONSTITUTION:The analogue signal is subjected to A/D conversion in 2 and has the higher forecast signal subtracted by subtracting circuit 16 and is delayed by delay circuit 7 of one-sample components and has the forecast signal of the minimun degree subtracted by subtractor 15, thus obtaining a forecast error signal finally. The forecast error signal is quantized in 4, and the quantized outpt signal is transmitted as code output 14 to the transmission line. Meanwhile, the quantized output signal is added to the forecast signal in 5 and delayed in 6 by one-sample components, and respective past sample values are multiplied by coefficients A1-A3 in coefficient circuit 9-11. The first loop for the minimum degree is input to adding circuit 13 and subtracting circuit 15. In the second loop for the higher degree except the minimum degree, signal components obtained by delaying the output of adding circuit 12 in delay circuit 7 of two-sample components by one sample are subtracted from the input signal in subtracting circuit 16, and further, signal components delayed by two samples are added to the forecast signal of the minimum degree in 13.