Method for identifying QAM mode based on channel estimation and equalization

A channel estimation and pattern recognition technology, applied in the field of digital signal transmission, can solve problems such as slow convergence speed and inability to meet equalization requirements, and achieve the effect of data equalization

Active Publication Date: 2010-05-19
SHENZHEN STATE MICRO TECH
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AI Technical Summary

Problems solved by technology

The traditional equalizer needs to perform channel estimation and equalization on the input data under the known QAM mode, and at the same time, the convergence speed is slow, and it cannot adapt to the equalization requirements under different QAM modes.

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  • Method for identifying QAM mode based on channel estimation and equalization
  • Method for identifying QAM mode based on channel estimation and equalization
  • Method for identifying QAM mode based on channel estimation and equalization

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Embodiment Construction

[0024] Since in the digital TV cable broadcasting (DVB-C) system, the receiving end is unknown to the information data transmitted by the transmitting end, a blind equalization algorithm must be used, usually a constant modulus algorithm (Constant Modulus Algorithm, CMA). The main feature of this algorithm is to converge the input data to the equalizer to the average energy circle (radius), but it brings a serious disadvantage, that is, to converge all the input data to the energy radius. Higher-order QAM modulation is particularly outstanding.

[0025] In order to solve this problem, the present invention discloses an easy-to-implement CMA algorithm. Wherein, the formula of the traditional blind equalization algorithm is as follows: e(n)=R 2 -|y(n)| 2 .

[0026] The present invention amends it, and the revised formula is as follows: e (n)=(R 2 +L*T 2 )-(L+1)*|y(n)| 2 .

[0027] In the above formula: R 2 = E ...

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Abstract

The invention relates to a method for identifying a QAM mode based on channel estimation and equalization. The method comprises the following steps of: A, receiving input data in a QAM mode; B, adjusting the energy of the received data with a first convergence step length to make the data signal energy larger than an energy threshold; C, carrying out the equal convergence with a second convergence step length, and carrying the phase position and frequency offset correction on the received data when signal carrier recovery frequency-offset detection is locked; D, carrying out the equal convergence with a third convergence step length, and detecting whether the mean square error of the converged data is less than a threshold, if yes, going to Step E, otherwise, going to Step F; E, carrying out the LMS adaptive equal convergence on the input data by an equalizer, and detecting whether the mean square error of the converged data is less than a threshold, if yes, inputting data by the LMS adaptive equal convergence, otherwise, going to Step F; and F, changing the QAM mode and going to Step B. The invention effectively realizes the data equalization and completes the QAM mode identification in a simple and easily achievable mode.

Description

technical field [0001] The invention relates to the field of digital signal transmission, in particular to a channel equalization method under QAM mode recognition in cable digital television. Background technique [0002] The digital cable TV system provides broadcast services based on the cable TV network, converts analog TV signals into digital signals and processes and transmits them digitally. [0003] So far, several different digital cable TV standards have been formed in the world. Taking Europe as an example, since 1995, Europe has successively released the digital TV terrestrial broadcasting (DVB-T), digital satellite broadcasting (DVB-S), and digital TV cable broadcasting (DVB-C) standards. In 2001, China also started the trial broadcasting of digital cable TV. [0004] In the digital television cable broadcasting (DVB-C) standard, since all parameters of the signal transmitted by the transmitting end are unknown to the receiving end, and the transmitted signal ...

Claims

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Application Information

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IPC IPC(8): H04L25/03H04L25/02
Inventor 王长龙陈燕生
Owner SHENZHEN STATE MICRO TECH
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