Phase modulation

Phase modulation is a way of changing information (like music or talking) into a signal that can be sent through the air or through a wire to be heard by someone else.

Think of it like a game of Simon Says. If Simon says "jump", you jump. But if Simon says "clap", you clap. In phase modulation, the signal (like Simon) tells the carrier wave (like you playing the game) what to do. If the signal tells the carrier wave to change phase, then it does exactly that.

But what is phase, you ask? Phase is like where you are in a circle. When you start at the top, you're at 0 degrees. When you go a quarter of the way around, you're at 90 degrees. Halfway around, you're at 180 degrees. And so on.

In phase modulation, the signal is changing the phase of the carrier wave. Imagine you're on the phone with someone and they're playing music. When the singer says a high note, the signal tells the carrier wave to be at a certain phase. When the singer says a low note, the signal tells the carrier wave to be at a different phase.

So, in summary, phase modulation is a way of changing information into a signal that uses the phase of the carrier wave to send that information through the air or through a wire. Just like Simon Says, the signal tells the carrier wave what to do by changing its phase at certain moments.