Define Modulation. Why is it necessary?

Question

Accepted Answer

>

> [!TLDR]
> Modulation superimposes a low-frequency message signal on a high-frequency carrier wave so that it can be transmitted efficiently; it is needed because of antenna-size, power-radiation, and multiplexing limitations of raw low-frequency signals.
>
> **Definition:** Modulation is the process in which some characteristic (amplitude, frequency, or phase) of a high-frequency carrier wave is varied in accordance with the instantaneous value of a low-frequency message (information/audio) signal.
>
> **Why it is necessary:**
> 1. **Size of antenna:** For efficient radiation, an antenna must have a length comparable to $\lambda/4$ of the signal. Audio signals (20 Hz – 20 kHz) have wavelengths of thousands of kilometres, requiring impossibly large antennas. Modulated high-frequency carriers have short wavelengths, so practical antenna sizes (a few metres) suffice.
> 2. **Effective power radiated:** Power radiated by an antenna varies as $(\ell/\lambda)^2$; low-frequency signals radiate negligible power, while high-frequency carriers radiate effectively. …

Q.Define Modulation. Why is it necessary?

Concept understanding — Need for Modulation

Q.Define Modulation. Why is it necessary?

🎓Unlock everything free for 14 days

Unlock everything free for 14 days