Abstract: A device for characterizing the formation of a sheet material is described. The device comprises a basis weight sensor for measuring the basis weight of the sheet material as the material moves through the sensor and signal processing circuitry which receives a signal from the basis weight sensor indicative of the measured basis weight. The basis weight sensor includes a light source for directing a beam of light at the moving sheet and a light detector which detects the beam after it passes through the sheet. This detector produces a signal indicative of the intensity of the detected beam and transmits the signal to the signal processing circuitry. To calibrate the signal processing circuitry, a rotatable opaque wheel having a plurality of slots is positioned in the path of the light beam. The rotating wheel alternately blocks the light beam and allows the beam to pass through the slots to the detector.

Abstract: A system is provided for measuring the velocity of vibrations in a moving web, such as a sheet of paper. The system includes a transmitter coupled to the paper to transmit waves and a receiver to receive the waves. A signal processing system is used to determine the velocity.