G8A12 : What is QPSK modulation?
A
Modulation using quasi-parallel to serial conversion to reduce bandwidth
B
Modulation using quadra-pole sideband keying to generate spread spectrum signals
C
Modulation using Fast Fourier Transforms to generate frequencies at the first, second, third, and fourth harmonics of the carrier frequency to improve noise immunity
D
Modulation in which digital data is transmitted using 0-, 90-, 180- and 270-degrees phase shift to represent pairs of bits
Correct Answer: Modulation in which digital data is transmitted using 0-, 90-, 180- and 270-degrees phase shift to represent pairs of bits