Which of the following is an example of a digital modulation technique?

Explanation:

Digital Modulation Technique

Definition: Digital modulation refers to the process of modifying a carrier signal to encode digital information. This is achieved by altering the carrier's properties such as amplitude, frequency, or phase. Digital modulation techniques are fundamental in modern communication systems, as they enable efficient and reliable transmission of digital data over various communication channels.

Phase Shift Keying (PSK):

Definition: Phase Shift Keying (PSK) is a digital modulation technique where the phase of the carrier signal is varied to represent digital data. Each unique phase state corresponds to a specific binary or multi-bit symbol, allowing the transmission of information.

Working Principle: In PSK, the carrier signal's phase is shifted to encode digital information. For example:

• BPSK (Binary Phase Shift Keying): Two distinct phase states (e.g., 0° and 180°) are used to represent binary data (0 and 1).
• QPSK (Quadrature Phase Shift Keying): Four phase states (e.g., 0°, 90°, 180°, and 270°) are used, with each phase state representing two bits of data.
• Higher-Order PSK: More phase states (e.g., 8-PSK, 16-PSK) are used to represent more bits per symbol, increasing the data transmission rate.

Advantages of PSK:

• High spectral efficiency, allowing more data to be transmitted within a given bandwidth.
• Resilience to noise and interference, especially in low signal-to-noise ratio (SNR) environments.
• Widely used in modern digital communication systems, including wireless networks, satellite communications, and optical fiber systems.

Disadvantages of PSK:

• Complexity increases with higher-order PSK, requiring sophisticated demodulation techniques.
• Performance can degrade in the presence of severe phase noise or synchronization issues.

Applications: PSK is extensively used in various digital communication systems, including Wi-Fi, cellular networks, and satellite communications, due to its efficiency and robustness.

Correct Option Analysis:

The correct option is:

Option 3: Phase Shift Keying (PSK)

This option correctly identifies PSK as an example of a digital modulation technique. PSK is a widely used method for encoding digital information by varying the phase of the carrier signal, making it a fundamental concept in digital communication systems.

Important Information

To further understand the analysis, let’s evaluate the other options:

Option 1: Single Sideband Modulation (SSB)

SSB is a type of analog modulation technique used in amplitude modulation (AM) systems. It involves transmitting only one sideband (either the upper or lower sideband) of the modulated signal while suppressing the carrier and the other sideband. SSB is primarily used in analog communication systems, such as amateur radio and long-distance voice communication, and is not an example of a digital modulation technique.

Option 2: Narrow Band FM

Narrow Band FM is another analog modulation technique where the frequency of the carrier signal is varied in proportion to the modulating signal. It is used in applications such as two-way radio communication and public safety communication. Similar to SSB, it is not a digital modulation technique.

Option 4: Double Sideband Amplitude Modulation

This is a classical analog modulation method where both the upper and lower sidebands are transmitted along with the carrier signal. It is commonly used in AM radio broadcasting but is not related to digital modulation techniques.

Conclusion:

Understanding the distinction between analog and digital modulation techniques is crucial for identifying the correct option. Among the options provided, only Phase Shift Keying (PSK) is a digital modulation technique, as it involves encoding digital information by varying the phase of the carrier signal. The other options, including Single Sideband Modulation (SSB), Narrow Band FM, and Double Sideband Amplitude Modulation, are examples of analog modulation techniques, which are fundamentally different from digital modulation.