Patent ID: 7327136
Filing Date: 2008-02-05
Classification: G05D

Abstract:
1. A method of monitoring a volume ratio of at least two components mixed together comprising the steps of: a. mixing a predetermined amount of ferrous taggant particles with a predetermined first volume of a first component of a building material to prepare a first mixture in a first mixing device; b. providing a first sensor for generating a first sense signal representing an amount of ferrous taggant particles per unit volume of the first mixture flowing into a second mixing device; c. mixing a predetermined second volume of a second component of the building material with the first mixture to prepare a second mixture in the second mixing device; d. providing a second sensor generating a second sense signal representing an amount of ferrous taggant particles per unit volume of the second mixture flowing from the second mixing device; e. providing a control means for calculating a ratio of the volumes of the first and second components in the second mixture in response to said first and second sense signals; and f. generating a sine wave test signal with a frequency of “n” times a frequency of the first and second sense signals, gathering four points ninety degrees apart for each of “n” cycles of the test signal, subtracting a first one of the points from a third one of the points and subtracting a second one of the points from a fourth one of the points to obtain a pair of points for each of the cycles, and averaging a first one of all of the pairs of points and averaging a second one of all of the pairs of points to obtain first and second averages respectively, the first and second averages representing an amplitude and phase of the first and second sense signals.