Mass flow measurement methods, apparatus, and computer program products using mode selective filtering

Abstract

Mass flow of a material in a conduit is estimated by mode selective filtering a plurality of motion signals representing motion of the conduit to generate a plurality of mode selective filtered motion signals such that the mode selective filtered motion signals preferentially represent motion associated with a vibrational mode of the conduit. A plurality of phase estimates is generated from the plurality of mode selective filtered motion signals. A mass flow estimate is generated from the plurality of phase estimates. The plurality of phase estimates may be estimated using a phase reference derived from one of the plurality of mode selective filtered motion signals. In some embodiments, a frequency of a mode selective filtered motion signal of the plurality of mode selective filtered motion signals is estimated. Quadrature first and second reference signals are generated based on the estimated frequency. The plurality of phase estimates is generated from the plurality of mode selective filtered motion signals and the first and second reference signals. A plurality of time difference estimates may be generated from the plurality of phase estimates, and the mass flow estimate may be generated from the plurality of time difference estimates. The plurality of time difference estimates may be generated from the plurality of phase estimates by dividing the plurality of phase estimates using a mode frequency estimated from the mode selective filtered motion signals. The invention may be embodied as methods, apparatus and computer program products.