# Wavelet doubts about the coefficients

Started by March 5, 2010
```My current work is about analyzing vibration is a signal from an
accelerometer in a moving vehicle. After some math operations we get a
signal that represents the vertical displacement of the vehicle versus
travel distance. No big deal.

We want to locate ithe intervals where excess vibration occurred, in a
certain frequency band (loose), and have applied Discrete Wavelet
Transform to that effect. Analyzing the coefficients in that frequency
band we can locate the intervals where the vibration was higher. The
thing seems to be working as planned, with actually pretty good and
motivating results.

Now come our doubts: why look at the coefficients (which time
resolution has been reduced, depending on the level you are) and not
reconstruct the signal corresponding to that coefficients, therefore
gaining the original time resolution and squaring it (to get energy,
likewise with the coefficients).

So, the question is basically should we reconstruct the signal and
square it to get energy, or use the wavelet coefficients which
represent energy, anyway.