Nowadays, the engineering practice raises far more vibration problems than can be theoretically explained or modelled. Because Df this, measurements are used in almost all fields of industry, transportation and civil engineering in studies of mechanical and structural vibration. They are an invaluable tool for designing products and machines with high reliability and low noise level, vehicles and buildings with improved comfort and resistance to dynamic loads, as well as for obtaining increased safety of opera tion and optimum running parameters. In order to cope with the increasing demand...