PSK (Phase Shift Keying)
Definition
Phase Shift Keying (PSK) is a digital modulation scheme that conveys data by changing (modulating) the phase of a reference carrier signal while maintaining constant frequency and amplitude.
Detailed Explanation
Working Principle
- Digital data encoded in phase changes
- Constant amplitude and frequency
- Phase shifts represent different symbols
Types of PSK
-
Binary PSK (BPSK)
- Two phases (0° and 180°)
- One bit per symbol
- Most robust PSK variant
-
Quadrature PSK (QPSK)
- Four phases (45°, 135°, 225°, 315°)
- Two bits per symbol
- Higher data rate than BPSK
-
8-PSK and Higher
- Eight or more phases
- Three or more bits per symbol
- Higher bandwidth efficiency
Applications
- Satellite communications
- Wi-Fi (802.11)
- Mobile communications
- Digital cable television
Performance Characteristics
- Better noise immunity than ASK/FSK
- High spectral efficiency
- Complex implementation
- Used in modern high-speed communications