Filters Explained: What Are DSP Filters?

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Discussion Overview

The discussion revolves around digital signal processing (DSP) filters, specifically exploring the definitions and characteristics of various types of filters such as FIR, IIR, Butterworth, and Chebyshev filters. Participants seek to clarify these concepts in accessible language, touching on different filter types and their functions in signal processing.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant requests a plain English explanation of DSP filters, including FIR and IIR filters, and various filter types like Chebyshev and Butterworth.
  • Another participant suggests that every signal can be viewed as a sum of sinusoids, indicating that filters can block certain frequencies, with low pass filters blocking high frequencies.
  • A participant elaborates on the definitions of different filter types, explaining that a lowpass filter allows frequencies below a cutoff frequency, while a highpass filter allows frequencies above a cutoff frequency.
  • The same participant describes bandpass and stopband filters, noting that FIR filters have a finite-duration impulse response and IIR filters can have an infinite-duration impulse response.
  • They also explain the characteristics of Butterworth and Chebyshev filters, highlighting the differences in their frequency responses and design goals.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and clarity regarding DSP filters, with some definitions and explanations being agreed upon, while the overall complexity and technicality of the topic remain a point of contention.

Contextual Notes

The discussion reflects a range of assumptions about prior knowledge of DSP concepts, and some participants express a desire for less technical explanations, indicating potential gaps in foundational understanding.

blackout77
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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).
 
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http://www.dspguru.com/info/terms/filtterm/index.htm
 
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Is this homework?

- Warren
 


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


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.
 


blackout77 said:
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
 

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