Difference quadrature phase keying system, method and device

Abstract

The embodiment of the invention discloses a difference quadrature phase keying system, a method and a device. The system comprises a transmitting end and a receiving end; wherein, the transmitting end is used for pre-coding input first original signal and second original signal to generate an in-phase signal and a quadrature signal; the in-phase signal is modulated to generate a first NRZ-DPSK signal, the quadrature signal is modulated to generate a second NRZ-DPSK signal, and a signal in the first NRZ-DPSK signal and the second NRZ-DPSK signal is subjected to phase shift of 90 degrees and interferes with another signal to obtain a difference quadrature phase keying DQPSK signal which is sent to the receiving end; the receiving end is used for demodulating the DQPSK signal from the transmitting end in the mode of disharmonious filtering and for restoring the first original signal and the second original signal by photoelectric conversion. The invention avoids precise control to the phase difference of two arms of an asymmetric Mach-Zehnder interferometer, is easy to control and adjust signals and can lower system cost to a large extent.

Description

technical field [0001] The present invention relates to the field of communication technology, in particular to a differential quadrature phase-shift keying system, method and equipment. Background technique [0002] Differential quadrature phase shift keying (Differential Quadrature Phase Shift Keying, DQPSK) signal has high spectrum utilization efficiency, under the same symbol rate condition, the dispersion tolerance can be maintained, and the system capacity can be increased to differential phase shift keying ( Differential Phase Shift Keying, DPSK) signal twice. At the same time, since the DQPSK signal can achieve constant envelope or approximately constant envelope transmission, it can effectively suppress the nonlinear effects of various optical fibers, such as Cross-Phase Modulation (Cross-Phase Modulation, XPM), Self-Phase Modulation (Self-Phase Modulation, SPM), etc., so the DQPSK signal has a good application prospect in high-speed and large-capacity transmission...

AI Technical Summary

Problems solved by technology

[0011] In the prior art, two AMZIs and two balanced detectors are used to demodulate each signal at the receiving end of the system, and the system structure is relatively complicated; the control of the AMZI phase shift needs to be very precise, and the determined AMZI can only be applied to The definite working rate is not conducive to the control and adjustment of the signal; after the demultiplexer and multiple branching and combining, the signal power loss is relatively large

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