Deep Dive: G8A12
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.
Why Other Answers 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.
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 Example
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.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G8A
Reference: 2023-2027 Question Pool · G8 - Signals and Emissions
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G8A topic.