Let's set up the display to have a recorder, scope and camera picture in one display.

On the recorder we see nicely how the acceleration, velocity and displacement are phase shifted by 90 deg one to another. This is in accordance to the theory - if sine function is integrated, cosine results.

We use the scope to see the base acceleration of the shaker (green curve) and the top acceleration. Since the natural frequency is 90 deg phase shifted to the base movement, we can use this scope to set the correct frequency of the function generator to have maximum response.

Measurement

For the vibration measurement one of the most useful displays is the FFT screen . FFT decomposes the waveform to the series of sine waves and there we can clearly see the cause of the vibrations (on a rotating machine we can clearly see unbalance, misalignment, bearing faults and other errors). With modal testing, we can easily see natural frequencies in FFT and it can be used in a special form (3D FFT) as order tracking for run-up's and coast downs.

Measurement - FFT screen

With this test, the only point of interest thing to see is the non linearity of the excitations (errors of the sine wave), since the shaker output should be a pure sine wave.