Pulsation

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Etymology

Middle English puls, from Anglo-French, from Latin pulsus, literally, beating, from pellere to drive, push, beat

Definitions

  • 1 a : the regular expansion of an artery caused by the ejection of blood into the arterial system by the contractions of the heart
b : the palpable beat resulting from such pulse as detected in a superficial artery; also : the number of individual beats in a specified time period (as one minute) <a resting pulse of 70>
  • 2 a : underlying sentiment or opinion or an indication of it
b : vitality
b : beat, throb
  • 4 a : a transient variation of a quantity (as electric current or voltage) whose value is normally constant
b (1) : an electromagnetic wave or modulation thereof of brief duration (2) : a brief disturbance of pressure in a medium; especially : a sound wave or short train of sound waves
  • 5 : a dose of a substance especially when applied over a short period of time <pulses of intravenous methylprednisolone>

Description

In signal processing, the term pulse has the following meanings:

  • 1. A rapid, transient change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value.
  • 2. A rapid change in some characteristic of a signal, e.g., phase or frequency, from a baseline value to a higher or lower value, followed by a rapid return to the baseline value.
  • Pulse shapes

Pulse shapes can arise out of a process called pulse-shaping. Optimum pulse shape depends on the application.

  • Rectangular pulse

These can be found in pulse waves, square waves, boxcar functions, and rectangular functions. In digital signals the up and down transitions between high and low levels are called the rising edge and the falling edge. In digital systems the detection of these sides or action taken in response is termed edge-triggered, rising or falling depending on which side of rectangular pulse. A digital timing diagram is an example of a well-ordered collection of rectangular pulses.

  • Nyquist pulse

A Nyquist pulse is one which meets the Nyquist ISI criterion and is important in data transmission. An example of a pulse which meets this condition is the sinc function. The sinc pulse is of some significance in signal-processing theory but cannot be produced by a real generator for reasons of causality.

  • Gaussian pulse

A Gaussian pulse is shaped as a Gaussian function and is produced by a Gaussian filter. It has the properties of maximum steepness of transition with no overshoot and minimum group delay.[1]