Contents
How the PWM signal is generated?
In PWM, the time period of the square wave is kept constant and the time for which the signal remains HIGH is varied. The PWM generates the pulses on its output in such a way that the average value of HIGHs and LOWs is proportional to the PWM input. A PWM signal is a constant period square wave with varying duty cycle.
What is the application of PWM?
PWM is used in many applications, ranging from communications to power control and conversion. For example, the PWM is commonly used to control the speed of electric motors, the brightness of lights, in ultrasonic cleaning applications, and many more.
How is a PWM signal generated in a detection circuit?
The PWM signal received at the input of the detection circuit is contaminated with noise. This signal is applied to pulse generator circuit which regenerates the PWM signal. Thus, some of the noise is removed and the pulses are squared up. The regenerated pulses are applied to a reference pulse generator.
How can I tell if my monitor is using PWM?
You can test this by setting your hardware brightness to 100%. When your hardware brightness is set to 100% your monitor doesn’t use PWM in all cases and you should see this smooth line. Now set your hardware brightness to the minimum possible value. If your monitor uses DC dimming instead of PWM the test line should look smooth like this
Is it possible to separate PWM signal from noise?
Synchronization between the transmitter and receiver is not essential (Which is essential in PPM). It is possible to reconstruct the PWM signal from a noise, contaminated PWM, as discussed in the detection circuit. Thus, it is possible to separate out signal from noise (which is not possible in PAM).
How is a low pass filter used in PWM?
A low pass filter is used to recover the original modulating signal back from the PAM signal. The waveforms for this circuit have been shown in fig.4. Less effect of noise i.e., very good noise immunity. Synchronization between the transmitter and receiver is not essential (Which is essential in PPM).