Filter

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A filter is the field of signal processing removes unwanted components from a signal. Filters can fall into many categories, with some instances overlapping, such as analog/digital, linear/non-linear, passive/active, etc.


Technical Details

By far the most common type of filters are linear continuous-time filters. These filters are meant to remove certain frequencies while allowing others to pass.

Common Terminology

  • Low Pass Filter – frequencies below a threshold are passed while high frequencies are attenuated
  • High Pass filter – frequencies below a threshold are passed while low frequencies are attenuated
  • Band Pass filter – only frequencies withing a certain band are passed
  • Band Stop filter – only frequencies withing a certain band are attenuated.
  • Notch filter – a very small band Band-stop filter that cuts out one specific frequency
  • Comb filter – has multiple, narrow pass bands, regularly spaced
  • All Pass filter – passes all frequencies but modifies the phase
  • Cutoff frequency - frequency beyond while signals will be passed
  • Roll-off - rate of attenuation above the cutoff frequency
  • Transition band - the band between the start- and stop-band
  • Ripple - the variation insertion loss in the passband of the filter

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NOTE: All information contained within this article is pure opinion. Although this article is intended to help people, it may contain faulty or misleading information. This article is not to be considered professional opinion or advice, and is in no way a replacement for reading all safety/instructional documentation. Always remember to protect yourself when handling/using hazardous materials, as well as test new techniques before using them on projects/work intended to be handed in or used.

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