I am dealing with vibration signals which were acquired from different systems. They are mostly non-stationary and in some cases cyclostationary. What are the less expensive methods for removing noise from the signals? It can be parametric or non-parametric.
I would try something more simple than the above methods, with the advantage that you stay in control of your algorithms and what they do to your signal:
-vibration mechanics derive from source physical phenomena repeating themselves over time, and amplifying at each cycle.
You could assume a predictor of quasi period T, and to take account of uncertainty identify a three terms (or more) periodicity predictor s(t) = a(T)s(t-T)+a(T-1)s(t-T+1)+a(T+1)s(t-T-1)+ s'(t)
In reality you track an s'(t), your signal s minus the vibration, which is "normal behaviour without vibration".
The repeated or quasi periodic part formed of the amplified past samples at t-T (with T+/-1 or additional uncertainty/oscillating terms) describes the vibration.
The estimating algorithm is calculating the "a" amplification coefficients and period T, on observations s, in a time window, minimising the energy of the residual signal (after prediction) s'.
It is a maximum likelihood method.
Try it, you will like it.
It works on biomedical signals (heart beat, ECG) and speech signal in vowels where this periodicity in T is present (they call it " long term predictor in voiced sounds")
Enjoy
Thank you so much Renaud Di Francesco
the method seems nice. It looks like a FIR filter. Can you introduce to me some resource (textbook, paper...) for that?
thanks Mohammad Amin Motamedi &
I will check them. For me the computation cost is also important.
Thanks Naeim Mousavi
It is useful. For me the computation cost and accuracy in frequency domain does matter. So I need to check which method works better.
Behrang Hosseini Aghdam I use 'db' and 'sym8' wavelet functions in MATLAB to denoise the ultrasonic signals. You can try!
Hello Dr Aghdam: "In order to improve the performance of the denoising method for vibration signals of rotating machinery, a new method of signal denoising based on the improved median filter and wavelet packet technology is proposed through analysing the characteristics of noise components and relevant denoising methods. " Take a look at the following useful link:
Article A New Method of Denoising of Vibration Signal and Its Application
Article Noise reduction method for vibration signals 2D time-frequen...
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