Which of the following is not used in analog communication?

Options

A. PAM
B. AM
C. FM
D. ASK

Answer

To determine which of the following is not used in analog communication, let's analyze each option provided:

1. **PAM (Pulse Amplitude Modulation)**:
- PAM is a form of modulation where the amplitude of a series of signal pulses is varied in proportion to the amplitude of the analog signal being sent. It is indeed used in analog communication systems.

2. **AM (Amplitude Modulation)**:
- AM is a well-known technique used in analog communication, particularly in radio broadcasting. It involves varying the amplitude of the carrier wave in accordance with the amplitude of the message signal.

3. **FM (Frequency Modulation)**:
- FM is another common method used in analog communication. It involves varying the frequency of the carrier wave in accordance with the amplitude of the message signal. It is widely used in radio transmission.

4. **ASK (Amplitude Shift Keying)**:
- ASK is a form of digital modulation where the amplitude of the carrier signal is varied to represent digital data. It is not used in analog communication systems, as it is primarily associated with digital communication.

Based on the analysis above, the option that is not used in analog communication is:

**Correct Answer: ASK (Option 4)**