Pulses Tutorial

Here is the characteristics of a single pulse.

• The voltage rises very rapidly from zero to its maximum value.
• It stays steady at the maximum value for a time.
• It then falls very rapidly back to zero.
• The duration of a pulse can be anywhere from a very long time (days) to a very short time (picoseconds or less).
• Pulses do not rise and fall instantaneously but take time (which may be very short).
• They are called the RISE and FALL times.

If pulses occur one after another they are called a PULSE TRAIN.
The duration time of a pulse is called the MARK.
The time between pulses is called the SPACE.
The relative times are expressed as the MARK/SPACE RATIO.
Mark/space ratios can vary.

Fig. 3 has a 50:50 mark/space ratio.
This is a special case called a SQUARE WAVE.
Fig. 4 is about 1:10
Fig. 5 is about 10:1
Note that the last three waveforms are of the same frequency. All the pulses start at the same instant.