| 摘要 |
1527207 Pulse code modulation WESTERN ELECTRIC CO Inc 20 April 1977 [23 April 19761 16521/77 Heading H3H In pulse code modulation, a plurality of code words from a direct feedback encoder 19 are accumulated during a conversion cycle in a first accumulator 21, 22, and the contents of register 22 are accumulated negatively in a second accumulator 27, 28 for a first portion of the cycle and positively for a second portion of the cycle, whereby at the end of the cycle registers 28, 31 hold a net sum in which successive words from encoder 19 during the first portion of the cycle are included an increasing number of times and successive words from the encoder 19 during the second portion of the cycle are included a decreasing number of times. The first and second portions of the cycle may abut, giving triangular weighting, or there may be an intervening portion in which the second accumulator does not accumulate, giving an overall trapezoidal weighting (which is a better approximation to theoretical parabolic weighting).
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