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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 monitoring system and modulation distortion technology, applied in transmission monitoring/testing/fault measurement system, phase-modulated carrier system, transmission system, etc., can solve the problems of reduced realizability and increased cost, and reduce repetition frequency and cost Low, Feasible Effects

Inactive Publication Date: 2014-07-23
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

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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 Patents(China)
IPC IPC(8): H04B10/07H04L27/20H04B10/077
Inventor 叶望闻和郑小平张汉一周炳琨
Owner TSINGHUA UNIV
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