Digital filters with a number of shift sequences in each pulse repetition interval

A method to increase the versatility of digital filters is described and analyzed. It is shown how the time between consecutive samples can be advantageously used to process further the stored information. This is achieved without the incorporation of any additional memory capacity, by recirculating the stored signals in the internal paths of the digital filters. During this process, the filter multiplication constants may take up new values in the various shift sequences. This processing leads to multiple output signals with different effective transfer functions. The form of the transfer functions makes them particularly suitable for the realization of variable filters, as desired variations of the filter characteristics can often be achieved by the variation of a single parameter. The method can also be used to reduce the requirement of coefficient accuracy in filters of second and higher degree.