A resonator produces a signal which is processed by being digitized and demodulated. The processed signal is applied to a filter having three sections. The first is a lowpass filter, the second is a decimator, and the third is an equalizer filter. The lowpass filter filters out the high frequency components which would be aliased by the decimator. The equalizer filter performs whatever processing as is appropriate for the measurement which is sought. A second or subsequent equalizer filter may be driven by the first. The lowpass filter and the equalizer filters all have the same architecture of allpass filters, weighting elements, and adders. The weights applied to the weighting elements vary to perform the varied purposes of the various filters. The filtered signal is applied to a display, such as a human operator, or a device (such as an auto-pilot) either in or out of a feedback loop, or both.
A process for transforming a plurality of data points n defining a high resolution profile for a parameter of a sheet material being manufactured into a low resolution profile for control of the parameter is disclosed. The process involves filtering the data points of the high resolution profile using an anti-aliasing filter function to create an intermediate profile and reducing the number of datapoints of the intermediate profile by an integer factor to create the low resolution profile to be used to control the parameter.
