Algorithms needed on filtering the noise caused by the vibration

Question

For example you measure the data coming from some device, it can be a mass of the object moving on the bridge. Because it is moving the mass will give data which will vibrate in some amplitude depending on the mass of the object. Bigger the mass - bigger the vibrations. Are there any methods for filtering such kind of noise from that data? May be using some formulas of vibrations? Have no idea what kind of formulas or algorithms (filters) can be used here. Please suggest anything. EDIT 2: Better picture, I just draw it for better understanding:

Not very good picture. From that graph you can see that the frequency is the same every time, but the amplitude chanbges periodically. Something like that I have when there are no objects on the moving road. (conveyer belt). vibrating near zero value. When the object moves, I there are the same waves with changing amplitude. The graph can tell that there may be some force applying to the system and which produces forced occilations. So I am interested in removing such kind of noise. I do not know what force causes such occilations. Soon I hope I will get some data on the non moving road with and without object on it for comparison with moving road case.

Answer 1

What you have in your last plot is basically an amplitude modulated oscillation coming from a function like:

 f[x] := 10 * (4 + Sin[x]) * Sin[80 * x]

The constants have been chosen to match your plot (using just a rule of thumb)

The Plot of this function is

That isn't "noise" (although may be some noise is there too), but can be filtered easily.

Let's see your data for the static and moving payloads ....

Edit

Based on your response to several comments, and based in my previous experience with weighting devices:

1. You are interfacing the physical world, not just getting input from a mouse and keyboard. It is very important for you understand the device, how it works and how it is designed.
2. You need a calibration procedure. You have to use several master weights to be sure that the device is working properly and linearly in the whole scale, and that the static case is measured much better than your dynamic needs.
3. You'll not be able to predict if you can measure with several loads in the conveyor until you do some experiments and look very carefully at the resulting plots
4. You need to be sure that a load placed anywhere in the conveyor shows the same reading. Or at least you should be able to correlate reading and position.

As I said before, you need a lot of info, and it seems that is not available. I always worked as a team with the engineers designing the device.

Don't hesitate to add more info ...

Answer 2

Have you tried filters with lowpass characteristics? There are different approaches for smoothing data (i.e. Savitzky-Golay, Gauss, moving average) but often, a simple N-point median filter is already sufficient.

It really depends on what you're after.