Effectiveness of Two-Step Smoothing in Digital Control Computers

An analysis is made of the effect, in smoothing observational data with a digital computer, of using two smoothing steps, the first having a high data handling rate and a short smoothing time, the second a low data handling rate and a long smoothing time. The analysis shows that for the most commonly used types of smoothing, the effect of the two smoothing operations in series is essentially equivalent to that of a single operation combining the most desirable features of each of the two, i.e., the high data handling rate of the first operation and the long smoothing time of the second. This fact is important in certain control applications where the combination of both these features in one smoother is not possible.