Pulse Characteristics and Terminology

The characteristics of a pulse are shown in figure 1.

Fig. 1 Pulse characteristics with parameters

Base line: It is referred to the DC level and is the line at which the pulse starts and finishes.

Base line shift: The shift of base line from zero volts, or the expected value, is called the base line offset. The amplitude of the pulse is measured from the base line to the steady state pulse value.

Pulse rise time: The pulse rise time is the time needed for the pulse to go from 10% to 90% of its amplitude. It is also known as leading edge transition time.

Pulse fall time: The pulse fall time is the time needed for the pulse to go from 90% to 10% of its amplitude. It is also known as trailing edge transition time.

Linearity: The linearity of the pulse is the deviation of an edge, from the straight line drawn through the 10% and 90% points, expressed as a per cent of the pulse amplitude.

Pulse preshoot: The pulse preshoot is the deviation prior to reaching the base line at the start of the pulse.

Pulse overshoot: The overshoot is the maximum height immediately following the leading edge.

Ringing: It is the positive and negative peak distortion, excluding overshoot.

Settling time: It is the period needed for pulse ringing to be within a specified percentage of the pulse amplitude, measured from 90% point to the leading edge.

Pulse droop or sag: It is the fall in pulse amplitude with time.

Pulse rounding: It is the curvature of the pulse at the leading and trailing edges.

Pulse width: The width of the pulse is measured, in units of time, between the 50% points on the leading and trailing edges. The pulse period is the time between equal points on the waveform.

Pulse repetition rate: The pulse repetition rate is a measure of how frequently a pulse occurs. It is equal to the reciprocal of the pulse period, and is measured in units of frequency.


Duty cycle: The duty cycle of the pulse is the ratio of its width to its period, usually expressed as a percentage.


Pulse jitter: It is a measure of short term instability of one event (starting time or pulse amplitude or pulse width) with respect to another. It is usually expressed as a percentage of the main parameter.

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