Abstract: Plural independent delay lines are connected in parallel and receive a first signal taken from a first point. Samples of the first signal are taken at different sampling frequencies and are respectively stored in the several delay lines. Samples of a second signal are taken from a second point and are stored in a direct line at one of the frequencies. The correlation function between the samples of the direct line and the samples of one of the delay lines is calculated. Exemplary applications include measuring the speed of a linearly translating object, such as a web of paper.