jlg@lanl.ARPA (12/01/84)
> ( line eater, line eater, eat me a line. Oh, while your at it, one for me too) > > " A digital transversal filter is used for the filtering after > oversampling. To understand the operation of the filter, we can > think of it as consisting of 96 elements, while the delay in each > element is (176.4 * 1000) ** -1s, i.e. a quarter of the sampling > period or 1/4 Ts. Four times in each period the filter takes up new > data. At three of these four times, the content of this data is > zero, since the oversampling is done by the introduction of > intermediate samples of value zero. This means that only 24 of the > 96 elements are filled at any one time. The contents of each > element are multiplied by a coefficient c. The filter provides data > at a rate of 176.4 kHz; each number is the sum of 24 non-zero > multiplications. In this way the filter always calculates three new > sample values at the locations of the zero samples." In other words, it's a 96 element discrete convolution integral implemented in hardware. Just what you'd expect a digital filter to look like.