PSK MODULATION & DEMODULATION

PSK Modulation and Demodulation: A Comprehensive Guide:

Introduction:-

Phase Shift Keying (PSK) is a popular digital modulation technique used in various communication systems. In this topic, we'll discuss into the  PSK modulation and demodulation, exploring the concepts, circuits, and applications in easy-to-understand terms.

Defination:

PSK is type of modulation technique where the phase of carrier is shifted between a corresponding distinct level. In case of BPSK (Binary PSK) there are two distinct level '1' or '0'.
For an example when the data bit goes from '1' to '0' the output PSK modulated wave from get phase shift of 180°, further when the data bit goes from '0' to '1' then another 180° phase shift operation is performed.


Mathematical expression of PSK signal:-

x(t)=Acos(2πft+ angle)        when data bit is '1'.
x(t)=-Acos(2πft+ angle)        when data bit is '0'.

where ,
A= amplitude of PSK output.

[For a clear explanation if we consider a carrier signal cos2πft that is multiplied with data bit signal. When data bit goes to '1' to '0' we get 180° phase shift means -cos2πft ] 

Let Amplitude (A)=1.



Block diagram of BPSK modulator &          demodulator.


PSK Modulation:

PSK modulation involves modifying the phase of a carrier wave to represent digital information. The process can be broken down into:

1. Carrier Wave Generation: A high-frequency carrier wave is generated.
2. Digital Input: A digital signal (0s and 1s) is applied to the modulator.
3. Phase Shift: The carrier wave's phase is shifted according to the digital input.
4. Modulated Output: The resulting modulated wave represents the digital information.

PSK Modulator Circuit:-
A simple PSK modulator circuit consists of:

1. Carrier Wave Generator: Produces the high-frequency carrier wave.
2. Digital Input Source: That's the binary sequence provides the digital signal (0s and 1s).
3. Phase Shifter: Shifts the carrier wave's phase according to the digital input.
4. Summer: Combines the phase-shifted carrier wave with the original carrier wave.

PSK Demodulation:-

PSK demodulation involves extracting the original digital information from the modulated wave. The process can be broken down into:

1. Received Signal: The modulated wave is received.
2. Phase Detection: The phase of the received signal is detected.
3. Digital Output: The detected phase is converted back to the original digital signal (0s and 1s).

PSK Demodulator Circuit:-

A simple PSK demodulator circuit consists of:

1. Phase Detector: Detects the phase of the received signal.
2. Low-Pass Filter: Removes high-frequency components.
3. Comparator: Converts the analog signal back to a digital output (0s and 1s).

Applications:-

PSK modulation and demodulation find applications in:

1. Wireless Communication:
Cellular networks, satellite communication, and wireless local area networks (WLANs).
2. Digital Radio: Digital radio broadcasting and reception.
3. Data Transmission: High-speed data transmission over wires or wireless channels.

Conclusion:

In conclusion, PSK modulation and demodulation are essential techniques in digital communication systems. Understanding the concepts and circuits involved can help you appreciate the complexity and beauty of modern communication systems.

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