The excitation levels for modal testing are usually reasonably low. There is no need to provide large force levels for conducting a modal test especially if appropriate response transducers (accelerometers) are selected with good sensitivity and resolution, as well as high quality, high resolution (24 bit technology standard in todays commercial offerings) data acquisition systems. The level only needs be sufficient enough to make good measurements. In fact, larger force levels tend to overdrive the structure, exciting nonlinear characteristics of the structure and providing poorer overall measurements than with lower level force tests. For this reason on larger structures, it is often desired to use multiple shakers at lower force levels to more evenly distribute force than a single shaker at a high level.