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MATLAB - Troubles filtering very noisy signals using narrow pass band filter

thread240-412773

MATLAB - Troubles filtering very noisy signals using narrow pass band filter

MATLAB - Troubles filtering very noisy signals using narrow pass band filter

(OP)
Hello,

I am trying to filter a very noisy signal but using a narrow pass band filter there is an undesireded behavior on ressults.
While narrower the filter is applied, more signal sections becomes unusable. I apply filters type Chebishev TI and TII, elliptic and Butterworth.
The figure attached shows an undesirable effect: in the first seconds the filtered signal remains without values. For narrower filters, the apparition of signal values are delayed even more.

Thanks in advance.

RE: MATLAB - Troubles filtering very noisy signals using narrow pass band filter

Narrow filters need time to "swing in". So, what you see is what you should expect to see.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: MATLAB - Troubles filtering very noisy signals using narrow pass band filter

Got to agree with skogsgurra. The steeper the filter you design, the longer the delay through the filter. If you look at the transfer functions, it's pretty obvious.

Benta.

RE: MATLAB - Troubles filtering very noisy signals using narrow pass band filter

That's similar to the way that machines are moved quickly through resonance to avoid high vibrations. Moving slowly thru resonance creates higher vibration than moving faster thru resonance.

The more lightly damped, the higher the steady state amplitude for given excitation. But the higher that steady state amplitude the longer it takes to put in all that energy to achieve that steady state amplitude.

=====================================
(2B)+(2B)' ?

RE: MATLAB - Troubles filtering very noisy signals using narrow pass band filter

Quote:

The more lightly damped, the higher the steady state amplitude for given excitation. But the higher that steady state amplitude the longer it takes to put in all that energy to achieve that steady state amplitude.
to finish the thought... the more lighly damped, the longer it will take to achieve the steady state amplitude.

=====================================
(2B)+(2B)' ?

RE: MATLAB - Troubles filtering very noisy signals using narrow pass band filter

Pick the filter to match the spectrum of the desired signal. The noise looks broadband.
Check out Weiner filter.

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