Non-recursive digital filter for filter multiplex operation - uses band-pass scanning at filter outputs in all filter channels

摘要

In order to carry out quick folding in several channels, a first Fourier computing unit follows the scanning device. An analogue-digital converter and a first store, combine the incoming signals in the form of digital numbers in blocks of length N; A computer unit carries out discrete Fourier transformation of input signals; a second store stores blocks of Fourier transforms and a third store stores the characteristic data of each channel. Filter coefficients Hn(i), and a parameter Ni define the position of the lower channel edge, and a number N; shows how many Fourier coefficients fall in the channel; a control unit combines Fourier coefficients in groups and applies them to a multiplier in which each Fourier coefficient is weighted by a filter coefficient.