Complex modulation formats such as binary phase-shift keying, quadrature phase-shift keying
and 64 quadrature amplitude modulation required for testing RF digital communications systems may be accomplished by driving the I/Q inputs with analog signals.
Alternatively, a parallel for MSK modulation can be derived that is equivalent to offset quadrature phase-shift keying
modulation with sinusoidal baseband pulse shaping.
Another example is channel sounders that employ a spread spectrum technique to study the amplitude and phase characteristics of a propagation channel. The channel sounder is usually a pair of devices: a transmitter that outputs a is channel sounders that employ a spread spectrum technique to study the amplitude and phase characteristics of a propagation channel. The channel sounder is usually a pair of devices: a transmitter that outputs a spread spectrum biphase-shift keying or quadrature phase-shift keying
modulated RF signal and a correlating receiver that monitors the distortions of a correlation peak due to multipaths and fading.
For example, a quadrature phase-shift keying
(QPSK) signal can be examined to determine how different values of a affect the vector diagram.
The digital communication formats include spread spectrum, quadrature amplitude modulation, AM and quadrature phase-shift keying
The model BAFL-28000G.d Ka-band linearizer decreases the spectral regrowth of single-carrier quadrature phase-shift keying
and digitally modulated signals.
A second data modulation format, offset quadrature phase-shift keying
(OQPSK), is favored due to its ease of implementation and relatively constant carrier envelope.
Figure 3 shows the display of [Pi]/4-digital quadrature phase-shift keying
(DQPSK) modulation error in the form of a constellation diagram.