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US4686644A Linear predictive coding technique with symmetrical calculation of Y-and B-values 失效
线性预测编码技术,对称计算Y和B值

Linear predictive coding technique with symmetrical calculation of Y-and
B-values
摘要:
A digital lattice filter includes a Y-adder (44) and a B-adder (106). The Y-adder (44) calculates the Y-values for a linear predictive coding voice compression technique and the B-adder (106) calculates the B-values. Each of the calculated B-values output by the B-adder (106) is input to a B-stack (118) for storage therein. The B-stack (118) delays the B-values for one sample period. Multiplier constants are contained in a K-stack (90) for output to both adders (44) and (106) for use in the multiplication operation. The final value is stored in a Y1-register (104). Each of the adders (44) and (106) are multiplexed to perform a multiplication operation followed by an addition operation to generate the respective Y- and B-values. A generated Y-value is stored in a Y-register (56) for use in the next sequential Y calculation. In addition, the generated Y-value is used as a multiplicand for generation of a B-value. Therefore, it is only necessary to store the Y-values for one clock cycle and the B-values for up to nine clock cycles, thus reducing the amount of storage space necessary. In addition, the use of two multiplexed adders reduces the required processing speed at each of the adders.
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