Greg is correct. You can't use the mathematical method shown for anything but a pure, single frequency sine wave. There is no simple calculation for a real world signal.
I ment FFT analyser. I should have said so to prevent confusion. Thanks.
Jim
A couple of thoughts.
1. Your instrument should be able to do the integration to velocity and maybe displacement. Beware of double integration to displacement - it adds a lot of noise.
2. To convert a single frequency mathematically use:
V=6.28fD and A=6.28fV where D=displacement in thousants...
