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Method and system for monitoring modulation distortion of return to zero-differential quadrature phase shift keying (RZ-DQPSK) optical signal

A technology for modulating distortion and optical signals, which is applied in phase-modulated carrier systems, transmission systems, electromagnetic wave transmission systems, etc., can solve the problems of reduced feasibility and increased cost, and achieves reduced repetition frequency, low cost, and strong feasibility Effect

Inactive Publication Date: 2012-07-04
TSINGHUA UNIV
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Problems solved by technology

For monitoring signals at high symbol rates, the method becomes more costly and less achievable

Method used

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  • Method and system for monitoring modulation distortion of return to zero-differential quadrature phase shift keying (RZ-DQPSK) optical signal
  • Method and system for monitoring modulation distortion of return to zero-differential quadrature phase shift keying (RZ-DQPSK) optical signal
  • Method and system for monitoring modulation distortion of return to zero-differential quadrature phase shift keying (RZ-DQPSK) optical signal

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Embodiment Construction

[0033] The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

[0034] The present invention is based on such considerations: For monitoring the delay of the I-way and the Q-way and the delay of the cutting pulse in the modulation process of the RZ-DQPSK optical signal, the existing method requires a high-rate photodetector and High-frequency band-pass filters are expensive. In contrast, through the method of pulsed coherent light sampling, the pulse repetition frequency of local oscillator light can be reduced, and low-speed photodetectors can be used in combination with low-speed analog-to-digital converters, thereby reducing experimental conditions and costs, and improving monitoring feasibility. sex.

[0035] The monitoring method of the present invention includes the monitoring of I-way, Q-way delay and cutting pulse delay,

[0036] First, the RZ-DQPSK optical signal is sampled coherently by pulsed ...

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Abstract

The invention discloses a method for monitoring the modulation distortion of a return to zero-differential quadrature phase shift keying (RZ-DQPSK) optical signal. The method comprises the following steps of: monitoring delays of paths I and Q and a chopped pulse delay, performing coherent light sampling on the RZ-DQPSK optical signal by utilizing pulsed light, constructing a state-transition diagram for data obtained by the sampling by using a digital signal processing algorithm, and matching the constructed state-transition diagram and a standard map depot to obtain a delay corresponding to optimal matching as a monitoring result. The invention also provides a system for implementing the method. The system comprises a state-transition diagram construction device and a state-transition diagram matching device, wherein the state-transition diagram construction device is used for sampling the RZ-DQPSK optical signal, and obtaining the state-transition diagram; and the state-transition diagram matching device is used for matching the obtained state-transition diagram and the standard map depot to obtain the final monitoring result. By the method and the system, the digital signal processing algorithm is adopted on the basis of a conventional coherent light detection system, so that system complexity is reduced; and by the matching of the state-transition diagram, modulation distortion judgment and monitoring performance can be improved.

Description

technical field [0001] The invention belongs to the technical field of optical signal modulation, in particular to a monitoring method and system for RZ-DQPSK optical signal modulation distortion. Background technique [0002] RZ-DQPSK (Return to Zero-Differential Quadrature Phase Shift Keying, Return to Zero-Differential Quadrature Phase Shift Keying) Differential Quadrature Phase Shift Keying (DQPSK) uses four relative phase differences of the carrier to transmit digital signals. It has High spectrum utilization, strong anti-interference, and relatively simple implementation on the circuit, has been widely used in wireless communication and has become a very important modulation and demodulation method in modern communication. The self-synchronization characteristic of the return to zero code makes the application of the return to zero code very extensive, and the RZ-DQPSK is obtained by combining with the differential quadrature phase shift keying. [0003] A common modu...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B10/08H04L27/20H04B10/077
Inventor 叶望闻和郑小平张汉一周炳琨
Owner TSINGHUA UNIV
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