A binary phase-shift keying
(BPSK) modulated signal is a simple example to describe the frequency error effect.
Carrier 2 is always located at a fixed-frequency offset that is 5 MHz below the frequency of carrier 1 and is used for PCM bit streams employing phase-shift keying
for the use of its Feher-Patented Quadrature Phase-Shift Keying
The transmitter consists of two chips: one chip incorporates an oscillator and M-number phase-shift keying
(PSK) modulator, the other is a three-stage power amplifier.
In the upstream direction, the CN9414 includes a Quadrature Phase-Shift Keying
(QPSK)/16 QAM burst modulator and a 10-Bit digital/analog (D/A) converter.
The tracking range is [+ or -]2 MHz for 64 kbps binary phase-shift keying
(BPSK) or 128 kbps for quadrature phase-shift keying
(QPSK), and [+ or -]1 MHz for 1 Mbps BPSK or 2 Mbps QPSK.
The CDMA signal must be transmitted in a linear fashion to maintain phase-shift keying
modulation and to prevent spectral regrowth into adjacent channels.
Since the modulation in such systems is quadrature phase-shift keying
, the distortion generated begins to increase rapidly.
IS-136, which uses [Pi]/4 differential quadrature phase-shift keying
(DQPSK) modulation, is a next-generation version of the IS-54B standard already in use in the cellular band.
This technology applies to a variety of products including biphase- and quadrature phase-shift keying
modulators, vector modulators, phase shifters and phase-free attenuators.
For example, phase-shift keying
(PSK) modulation represents digital information (bits or characters) by shifting, with respect to a reference, the phase of a carrier signal by an amount corresponding to each character.
When properly configured, the signal generators can generate many waveforms, including frequency- (FSK), amplitude- and phase-shift keying
, and quadrature amplitude modulation (QAM).