pulse width modulation

Pulse Width Modulation

Pulse Width Modulation (PWM) is a fancy term for describing a type of digital signal. Pulse width modulation is used in a variety of applications including sophisticated control circuitry. A common way we use them here at SparkFun is to control dimming of RGB LEDs or to control the direction of a servo motor. We can accomplish a range of results in both applications because pulse width modulation allows us to vary how much time the signal is high in an analog fashion. While the signal can only be high (usually 5V) or low (ground) at any time, we can change the proportion of time the signal is high compared to when it is low over a consistent time interval.

Pulse Width Modulation (PWM) or Pulse Duration Modulation (PDM) or Pulse Time Modulation (PTM) is an analog modulating scheme in which the duration or width or time of the pulse carrier varies proportional to the instantaneous amplitude of the message signal.

The width of the pulse varies in this method, but the amplitude of the signal remains constant. Amplitude limiters are used to make the amplitude of the signal constant. These circuits clip off the amplitude, to a desired level and hence the noise is limited.

The following figures explain the types of Pulse Width Modulations.

There are three variations of PWM. They are :

• -The leading edge of the pulse being constant, the trailing edge varies according to the message signal.
• -The trailing edge of the pulse being constant, the leading edge varies according to the message signal.
• -The center of the pulse being constant, the leading edge and the trailing edge varies according to the message signal.

Resource/s:

Analog Pulse Modulation. (n.d.). Retrieved from https://www.tutorialspoint.com/principles_of_communication/principles_of_communication_analog_pulse_modulation.htm