A WDM optical transmission system with automatic link gain adjustment and method thereof

Abstract

This invention relates to WDM light transmission system of a link gain automatic adjustment and an automatic adjust method. The invention detects a received light power of a light monitor channel wavelength at the lower-reach station of a given cross distance section and computes the fiber circuit loss of said section by the difference between sent light power of the upper reach station and the received light power of the lower reach station, then to adjust the light power attenuation value of the light adjustable attenuator of said section lower reach station based on the loss to match the circuit loss and the gain of light amplified relay.

Description

technical field [0001] The present invention relates to a wavelength division multiplexing optical transmission system with automatic link gain adjustment and a link gain automatic adjustment method used in the system, and the present invention is especially used for optical transmission in an optical dense wavelength division multiplexing (DWDM) transmission system Link single-span section gain automatic adjustment and full link gain automatic adjustment technology enable the optical amplification relay section and the entire optical transmission link in the DWDM system to automatically and effectively perform real-time automatic adjustment of link gain. Background technique [0002] In the existing WDM transmission system design, the gain of Erbium-doped fiber amplifier (EDFA) is mainly determined by the pump power, pump wavelength, and the length of Erbium-doped fiber. Once the length of Erbium-doped fiber, pumping wavelength, and power are determined Finally, it is not e...

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Problems solved by technology

[0005] However, the previously proposed automatic gain adjustment method uses the measurement of the power of the main optical channel to calculate the link attenuation of the span section

However, since the power change of the main optical channel is affected by the following factors, the number of light source channels changes, the parameters of all relay station equipment in the N spans before the amplifier of this station change, the aging of optical cables, and the process of automatic optical power reduction (APR) , power supply of this site and other factors

These multiple factors mixed together will cause changes in the main optical power received by the station, so the method of calculating the link attenuation of the span section by detecting the difference between the receiving and receiving optical power of the main optical channel is susceptible to interference

In addition, when comparing the transmit power of the front station with the receive power of the back station, due to the delay caused by power detection, line coding and decoding, transmission delay and other processes, it is not easy to achieve "synchronization" of the sampling of the transmitted and received optical power values. That is to say, the transmitted / received optical power for comparison is probably not collected at the "same moment"

Due to the influence of the above factors, on the one hand, the adjustment of EVOA may be very frequent, resulting in the mutual interference of optical amplification relay stations on the relay stations at all levels in the whole system, and also increasing the burden of the transmission power value of the optical monitoring channel and the calculation of the value by the processing equipment in the relay station. processing burden

On the other hand, it is not easy to detect the transmit / receive optical power at the "same moment" in terms of time, which has the potential danger of misadjusting and miscontrolling EVOA

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