Abstract: A method of digitally filtering signals with substantially differing signal levels, particularly in the processing of radio and radar signals, in which the level value of the relevant signal, at a predetermined point, is determined and compared with the maximum level value to be processed, a ratio value being formed from said two values, and if necessary, so altering the coefficient of at least one multiplication stage of the filter structure, in dependence upon such ratio, that at least a part of the individual filter units of the filter structure involved is fully loaded, and apparatus for practicing the method.