Signal Processing Filter

A Signal Processing Filter is a selective filter that removes or enhances certain components of a signal (such as specific frequencies).

• Context:
  • It can range from being a Analog Signal Processing Filter to being a Digital Signal Processing Filter.
  • It can operate in either the time domain or the frequency domain, depending on the desired processing effect.
  • It can be classified as either a Linear Filter or a Non-linear Filter depending on the relationship between input and output signals.
  • It can be an active filter or a passive filter depending on whether it requires external power for operation.
  • It can be categorized as either an Infinite Impulse Response (IIR) Filter or a Finite Impulse Response (FIR) Filter based on the way it processes input signals.
  • ...
• Example(s):
  • A low-pass filter used in audio equipment to reduce high-frequency noise in music recordings.
  • A band-pass filter applied in telecommunications to isolate specific frequency ranges for signal transmission.
  • A high-pass filter used in image processing to enhance the sharpness of edges by filtering out low-frequency information.
  • A Gaussian filter used in image processing to blur an image and reduce noise.
  • ...
• Counter-Example(s):
  • Non-filter-based signal processing techniques, which do not involve explicit filtering of frequency components (e.g., wavelet transforms).
  • Amplification circuits, which increase the amplitude of signals without modifying specific frequency ranges.
  • Convolutional Neural Network (CNN) Filters, which are designed to extract features from images but are not signal processing filters in the traditional sense.
• See: Finite Impulse Response, Signal Processing, Signal (Electronics), Frequency, Frequency Domain, Image Processing, Electronics, Telecommunication, Radio, Television, Audio Recording, Radar.

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References

2017

• (Wikipedia, 2017) ⇒ https://en.wikipedia.org/wiki/Filter_(signal_processing) Retrieved:2017-11-12.
  • In signal processing, a filter is a device or process that removes some unwanted components or features from a signal. Filtering is a class of signal processing, the defining feature of filters being the complete or partial suppression of some aspect of the signal. Most often, this means removing some frequencies or frequency bands. However, filters do not exclusively act in the frequency domain; especially in the field of image processing many other targets for filtering exist. Correlations can be removed for certain frequency components and not for others without having to act in the frequency domain. Filters are widely used in electronics and telecommunication, in radio, television, audio recording, radar, control systems, music synthesis, image processing, and computer graphics.

    There are many different bases of classifying filters and these overlap in many different ways; there is no simple hierarchical classification. Filters may be:

    • linear or non-linear.
    • time-invariant or time-variant, also known as shift invariance. If the filter operates in a spatial domain then the characterization is space invariance.
    • causal or not-causal: A filter is non-causal if its present output depends on future input. Filters processing time-domain signals in real time must be causal, but not filters acting on spatial domain signals or deferred-time processing of time-domain signals.
    • analog or digital.
    • discrete-time (sampled) or continuous-time.
    • passive or active type of continuous-time filter
    • infinite impulse response (IIR) or finite impulse response (FIR) type of discrete-time or digital filter.

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