A pulse wave, pulse train, or rectangular wave is a sequence of discrete pulses occurring in a signal over time. Typically, these pulses are of similar shape and are evenly spaced in time, forming a periodic or near-periodic sequence. Pulse waves outputs are widely used in tachometers, speedometers and encoders. Such pulse sequences appear in multiple fields of technology and engineering, where a pulse wave often denotes a series of electrical pulses generated by a sensor, or pulse wave is connected to signal processing and computer graphics, where a pulse wave is treated as a mathematical signal or function that repeats with a fixed period.