Q.Draw the block diagram of a receiver of AM radio wave. Explain each of the components used.

Demodulation reverses modulation — it strips the message signal back out of the modulated carrier wave received at the receiver.

At the transmitter, a low-frequency message (baseband) signal is superimposed onto a high-frequency carrier wave through modulation (e.g., amplitude modulation), so it can be transmitted efficiently over long distances. At the receiving end, this process must be reversed: the circuit that extracts the original message signal from the received modulated wave is called a demodulator, and the process is demodulation (or detection). For example, in amplitude demodulation, the modulated signal is rectified and then passed through a low-pass filter to recover the original envelope (message signal).

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An AM receiver's block diagram takes the modulated signal from the antenna through RF and IF stages to a detector, then an audio amplifier, to recover and reproduce the original signal.

Block diagram description — receiver for detection of an amplitude-modulated (AM) wave:

$\text{Antenna} \rightarrow \text{RF Amplifier} \rightarrow \text{Mixer} \leftarrow \text{Local Oscillator}$

$\rightarrow \text{IF (Intermediate Frequency) Amplifier} \rightarrow \text{Detector (Demodulator)} \rightarrow \text{Audio Amplifier} \rightarrow \text{Loudspeaker}$

• Antenna: picks up the transmitted AM radio wave.
• RF amplifier: amplifies the weak received radio-frequency signal and helps select the desired station's frequency band.
• Mixer + Local oscillator: the RF signal is mixed with a locally generated oscillator signal to produce a fixed, lower intermediate frequency (IF) signal (superheterodyne principle), which still carries the original modulation. …