What are common types of Phase Modulation?

What are common types of Phase Modulation?

• A. BPSK, QPSK, OQPSK.
• B. AM, FM, PM.
• C. QAM, PSK, FSK.
• D. SSB, CW, RTTY.

Answer: (A)

Phase modulation encodes information in the phase of the carrier. The most common practical phase-modulation schemes are BPSK, QPSK, and OQPSK. BPSK uses two phase states separated by 180 degrees, so each symbol carries one bit and the signal maintains a constant envelope, which makes it very robust to noise and nonlinearity. QPSK expands that idea to four phase states spaced 90 degrees apart, allowing two bits per symbol and doubling the data rate for the same bandwidth while still keeping a relatively constant envelope. OQPSK is a derivative of QPSK where the two components (in-phase and quadrature) are offset in time, which reduces abrupt amplitude changes during symbol transitions. This smoother envelope is beneficial in systems with nonlinear power amplifiers. Other choices mix in modulation types that aren’t purely phase-based (amplitude modulation, frequency modulation, or schemes that combine amplitude and phase like QAM), or refer to formats that aren’t phase-modulation variants.

Phase modulation encodes information in the phase of the carrier. The most common practical phase-modulation schemes are BPSK, QPSK, and OQPSK.

BPSK uses two phase states separated by 180 degrees, so each symbol carries one bit and the signal maintains a constant envelope, which makes it very robust to noise and nonlinearity. QPSK expands that idea to four phase states spaced 90 degrees apart, allowing two bits per symbol and doubling the data rate for the same bandwidth while still keeping a relatively constant envelope. OQPSK is a derivative of QPSK where the two components (in-phase and quadrature) are offset in time, which reduces abrupt amplitude changes during symbol transitions. This smoother envelope is beneficial in systems with nonlinear power amplifiers.

Other choices mix in modulation types that aren’t purely phase-based (amplitude modulation, frequency modulation, or schemes that combine amplitude and phase like QAM), or refer to formats that aren’t phase-modulation variants.