Development of hardware and software for a contactless gauge of linear translations and vibrations based on multi-port reflectometer

The paper describes advantages and disadvantages of the approach to measuring parameters of vibration using contact sensors, i.e. sensors having a mechanical contact with researched object. Several contactless measuring methods were analyzed: ultrasonic, radio wave, and optical. The contactless radio wave displacement gauge based on a classical multi-port reflectometer has been described. A new contactless measuring method of object displacement based on using multi-port reflectometer with frequency down conversion unit is proposed. Scheme of this meter and its basic equations are given. The advantages of proposed measurement scheme are discussed. The optimal statistical algorithms for measuring displacement of a surface under test is developed, which consists in optimal processing of the output signals of frequency down conversion unit by maximum likelihood method. The proposed measurement scheme in combination with developed optimal algorithm for processing information allows one to create a relatively inexpensive and precision meter of displacement and vibration parameters, which is capable to measure coordinates of researched object having an arbitrary shape with submillimeter accuracy and working under conditions of poor optical visibility and high temperatures. The results of carried out computer simulation of measurement process confirmed the theoretical conclusions.