| 摘要 |
PURPOSE:To eliminate the edge business phenomenon without increasing the number of the compression level by adding a simple circuit to the conventional predictive coding band compression device. CONSTITUTION:Deciding unit 30 and 50 plus companding level value converter 40 and 60 are added to the predictive coding band compression device. The signal is digitized through A/D converter 11 into signal S. The subtraction is given through subtractor 15 to signal S and output P of predictor 14 to obtain differential signal X. Ra = S = l3 is kept until time t1 by control of unit 30, and p =l3, X = 10, Y = L4 and Q = +13 are obtained at t1 for S when it changes to l4 =l3 + 10. And then Ra = P + Q = l3 + 13 < l4 + 3 is obtained. After this, the sampling is carried out in the same way at time t2 and t3. Thus, P = l4 + 1, X = -1, Y = L-1 and Q = -1 are obtained at time t4 and then Ra =l4 is given. And P = l4 and X = 0 and Y = L1 are obtained at time t5, and thus the FF within the deciding unit is set to turn forcedly Q = +1 to 0. |
