What are DSP filters and filter types?

[blackout77]

Filters what are they??

Can someone explain to me what are filters (DSP) in plain english? Fir filter, IIR filter,... Chebyshev, Butterworth,... Bands (stop, pass, lowpass, highpass).

 

[negitron]

http://www.dspguru.com/info/terms/filtterm/index.htm

 

[chroot]

Is this homework?

- Warren

 

[blackout77]

Nope, I just couldn't find a good explanation of what they are without getting into so much technicality.

 

[abros]

Every signal can be described as a sum of sinusoids with different frequencies. Simply put, filters can block certain frequencies in your signal. So for example, a low pass filter would block out the high frequency components of the signal.

 

[chroot]

Can someone explain to me what are filters (DSP) in plain english? Fir filter, IIR filter,... Chebyshev, Butterworth,... Bands (stop, pass, lowpass, highpass).

A "band" is a range of frequencies.

A lowpass filter passes all signal components with less than some critical frequency, called the cutoff frequency.

A highpass filter passes all signal components with greater than some cutoff frequency.

A bandpass filter passes only signal components within some band.

A stopband filter stops only signal components within some band.

FIR filters have a finite-duration impulse response. If you put an impulse (a signal that is zero everywhere except a very brief interval of time) into an FIR filter, the response will eventually die down to zero and stay there forever.

IIR filters have (potentially) infinite-duration impulse response. The output of an unstable IIR filter will oscillate forever in response to an impulse.

A Butterworth filter is a monotonically-decreasing filter with maximal passband flatness. Its frequency response gently decreases in amplitude with increasing frequency. It is a very easy-to-understand filter.

A Chebyshev filter is not monotonically-decreasing, and trades flatness in either the passband or stopband for a narrower transition between passband and stopband.

- Warren