公开(公告)号：US11204329B2

公开(公告)日：2021-12-21

申请号：US16422127

申请日：2019-05-24

Applicant: VALMET AUTOMATION OY

Inventor： Markku Mantyla ,  Jussi Graeffe ,  Pekka Jakkula

IPC: G01N21/86 ,  G01V3/08 ,  B65H7/10 ,  G01N21/31 ,  G01S17/02 ,  B65H7/14 ,  G01J5/10

Abstract: A method of measuring properties of a moving cellulose, paper or board sheet. A first parameter of a first resonance caused by the moving sheet in a frequency range 1 GHz to 25 GHz of electromagnetic radiation is measured. A second parameter of an electromagnetic signal transmitted between at least a pair of transceiver parts of a transceiver sensor located on opposite sides of the moving sheet through the moving sheet is measured in a frequency range 25 GHz to 1000 GHz. A minimum difference between the frequency ranges related to the first parameter and the second parameter being at least 5 GHz. Both the dry stuff content and the weight of water per unit of area are determined on the basis of the first parameter, the second parameter and available information related to a distance travelled by the electromagnetic signal.