Non-recursive digital filter and method for calculating coefficients of the filter

摘要

The nonrecursive digital filter has variable coefficients for the purpose of shifting the frequency response from one characteristic frequency fc1 to another characteristic frequency fc2. The method enables calculating the coefficients of the nonrecursive digital filter for shifting the frequency response of the filter from one characteristic frequency fc1 to another characteristic frequency fc2. The coefficients of a prototype of the filter are prescribed or calculated for a given sampling frequency, the continuous time impulse response associated with this prototype is calculated and the impulse response is sampled at the sampling frequency fa2=fa1* fc1/fc2. The new coefficients are thereby produced. The filter can then be operated with the new coefficients at the old sampling frequency. As an alternative, the new coefficients can be calculated from the coefficients of the prototype of the filter by interpolating the values of the continuous time impulse response at an interval of 1/fa2.