What is QPSK modulation?
The correct answer is D: Modulation in which digital data is transmitted using 0-, 90-, 180- and 270-degrees phase shift to represent pairs of bits. What QPSK modulation is modulation in which digital data is transmitted using 0-, 90-, 180- and 270-degrees phase shift to represent pairs of bits. QPSK uses four phase states to encode two bits per symbol. For amateur radio operators, this is how QPSK works. Understanding this helps when operating QPSK modes.
Exam Tip
QPSK = modulation using 0-, 90-, 180-, 270-degrees phase shift for pairs of bits. Think 'Q'PSK = 'Q'uadrature 'P'hase 'S'hift 'K'eying = '4' phase states for '2' bits. QPSK uses four phase states to encode two bits per symbol. Not conversion, not sideband keying, not FFT - just phase shift keying.
Memory Aid
"QPSK = modulation using 0-, 90-, 180-, 270-degrees phase shift for pairs of bits. Think 'Q'PSK = '4' phase states for '2' bits. QPSK uses four phase states to encode two bits per symbol. More efficient than BPSK."
Real-World Application
QPSK modulation: Digital data is transmitted using four phase shifts - 0°, 90°, 180°, and 270°. Each phase shift represents a pair of bits (00, 01, 10, 11). This allows QPSK to transmit two bits per symbol, making it more efficient than BPSK (one bit per symbol). This is how QPSK works.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. QPSK isn't quasi-parallel to serial conversion - QPSK is Quadrature Phase Shift Keying, not a conversion method. Conversion isn't QPSK.
Option B: Incorrect. QPSK isn't quadra-pole sideband keying - QPSK is phase shift keying, not sideband keying. Sideband keying isn't QPSK.
Option C: Incorrect. QPSK isn't Fast Fourier Transform harmonics - QPSK uses phase shifts, not FFT harmonics. FFT harmonics aren't QPSK.
题目解析
The correct answer is D: Modulation in which digital data is transmitted using 0-, 90-, 180- and 270-degrees phase shift to represent pairs of bits. What QPSK modulation is modulation in which digital data is transmitted using 0-, 90-, 180- and 270-degrees phase shift to represent pairs of bits. QPSK uses four phase states to encode two bits per symbol. For amateur radio operators, this is how QPSK works. Understanding this helps when operating QPSK modes.
考试技巧
QPSK = modulation using 0-, 90-, 180-, 270-degrees phase shift for pairs of bits. Think 'Q'PSK = 'Q'uadrature 'P'hase 'S'hift 'K'eying = '4' phase states for '2' bits. QPSK uses four phase states to encode two bits per symbol. Not conversion, not sideband keying, not FFT - just phase shift keying.
记忆口诀
QPSK = modulation using 0-, 90-, 180-, 270-degrees phase shift for pairs of bits. Think 'Q'PSK = '4' phase states for '2' bits. QPSK uses four phase states to encode two bits per symbol. More efficient than BPSK.
实际应用示例
QPSK modulation: Digital data is transmitted using four phase shifts - 0°, 90°, 180°, and 270°. Each phase shift represents a pair of bits (00, 01, 10, 11). This allows QPSK to transmit two bits per symbol, making it more efficient than BPSK (one bit per symbol). This is how QPSK works.
错误选项分析
Option A: Incorrect. QPSK isn't quasi-parallel to serial conversion - QPSK is Quadrature Phase Shift Keying, not a conversion method. Conversion isn't QPSK. Option B: Incorrect. QPSK isn't quadra-pole sideband keying - QPSK is phase shift keying, not sideband keying. Sideband keying isn't QPSK. Option C: Incorrect. QPSK isn't Fast Fourier Transform harmonics - QPSK uses phase shifts, not FFT harmonics. FFT harmonics aren't QPSK.
知识点
QPSK modulation, Phase shift, 0, 90, 180, 270 degrees, Pairs of bits
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.