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Dispersion compensation circuitry and system for analog video transmission with direct modulated laser

An optical transmission and circuit technology, applied in the field of electrical compensation, can solve problems such as the inability to meet the strict specifications of the full-bandwidth channel load and the limitations of broadband applications.

Inactive Publication Date: 2012-11-07
调谐公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] Unfortunately, all three schemes have severe limitations for broadband applications carrying full channel loads from 50 to 1000 MHz
Precompensation of laser chirp and fiber dispersion using known schemes generally cannot meet the strict specifications of full broadband channel loading using directly modulated laser sources, whether 1310nm or 1550nm

Method used

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  • Dispersion compensation circuitry and system for analog video transmission with direct modulated laser
  • Dispersion compensation circuitry and system for analog video transmission with direct modulated laser
  • Dispersion compensation circuitry and system for analog video transmission with direct modulated laser

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Embodiment Construction

[0028] The following detailed description refers to the accompanying drawings. The described preferred embodiments serve to illustrate the invention, not to limit its scope, which is defined in the claims. Those of ordinary skill in the art will recognize various equivalent variations in the ensuing description.

[0029] figure 2 Block diagram for part of an HFC distribution system. An input RF signal composed of multiple channels is provided to the transmitter 210 . The transmitter is designed to support a predetermined range of input frequencies. Preferably, but not necessarily, the transmitter is designed to support a broadband input RF signal comprising an analog signal modulated onto a video subcarrier in the frequency range from 50 MHz to 1000 MHz. In the transmitter, the input RF signal is provided to a precompensation unit 212 whose output is directly modulated onto a DFB laser source 214 . The optical output of DFB laser 214 is amplified in doped fiber amplifier...

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Abstract

An improved precompensation circuit includes a greatly improved differentiator in the dispersion precompensation path, a preprocessor in the dispersion precompensation path for reducing f2-f1 type Composite Second Order (CSO) distortion, and a broadband phase shifter for compensating undesired vector interaction between the laser predistortion and dispersion compensation.

Description

technical field [0001] The present invention relates to electrical compensation of fiber dispersion and laser-induced distortion in analog optical systems. Background technique [0002] Analog video signals are typically transmitted over hybrid fiber / coax (HFC) networks using dense wavelength division multiplexing (DWDM), where each channel is amplitude modulated onto separate subcarriers with a combined RF signal from a modulated laser source. These subcarriers are narrowly separated, for example by 6 MHz each in an NTSC channel scheme. (As used herein, a "subcarrier" is a type of "carrier," so either term may refer to a subcarrier as used herein.) [0003] Directly modulated DFB lasers (DMLs) have been widely used in HFC networks. 1310nm single-wavelength DML is the main technology in the forward application, because it can carry the full bandwidth of the signal to meet the system performance requirements. Recently, the channel load of the HFC network has been extended ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B10/18H04J14/02
CPCH04B10/25137H04B10/25133
Inventor 黄伟林志强陈立平
Owner 调谐公司