Method of implementing polynomial based open loop digital baseband predistorter

A digital baseband, predistorter technology, applied in broadcasting, electrical components, synchronization/start-stop system, etc., can solve the problems of demodulation error, complex hardware circuit, etc.

Inactive Publication Date: 2008-04-09
BEIJING BEIGUANGKE DIGITAL BROADCASTING TELEVISION TECH
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Problems solved by technology

[0004] The current digital baseband pre-distortion nonlinear correction requires a radio frequency feedback loop to compare with the original signal, and the radio frequency feedback circuit mainly includes down conversion, IQ demodulation, AD conversion, filtering and algorithm processing cpu and other units, the hardware circuit is relatively Complex, and there are problems such as demodulation error, delay alignment, etc., and inevitably introduce new distortion components

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  • Method of implementing polynomial based open loop digital baseband predistorter
  • Method of implementing polynomial based open loop digital baseband predistorter
  • Method of implementing polynomial based open loop digital baseband predistorter

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Embodiment Construction

[0064] image 3 It is a block diagram of a low-power DAB experimental transmission system including a digital baseband predistorter. The predistorter in the figure generates the cubic and quintic terms of the complex coefficients of the original digital baseband signal, and adjusts the amplitude coefficient α of the corresponding cubic and quintic terms through the man-machine interface 3 , α 5 and phase coefficient  3 ,  5 , to cancel the cubic quintic term generated by the nonlinearity of the RF power amplifier (HPA) of the final stage.

[0065] The above steps are realized by FPGA programmable logic language, and integrated into the FPGA chip of the DAB coding modulation board, and the actual measurement is carried out in the low-power DAB experimental launch system.

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Abstract

The invention relates to a method for implementing an open-loop digital baseband pre-distorter based on polynomial, which is a method for implementing the digital baseband pre-distorter, particularly relates to a method for implementing the open-loop digital baseband pre-distorter based on the polynomial suitable for various kinds of digital audio-video broadcasting systems such as DAB, DRM and DVB. The method comprises generating the cubic term and the quintic term of a complex coefficient of a primary digital baseband signal by using the universal mathematical model-polynomial model of various kinds of radio frequency power amplifier, and adjusting the amplitude and the phase of the complex coefficient through a man-machine interface to counteract the cubic term and the quintic term produced nonlinearly by the final radio frequency power amplifier. The invention is used for actual measurement for small-power experiment emitting system, and the result shows that the invention can well compensate for the nonlinearity of HPA, inhibit in-band and out-band distortion in a larger degree, and obviate the complex radio frequency feedback loop. The invention has simple implementation, obvious effect, and is suitable for various kinds of digital audio-video broadcasting systems.

Description

technical field [0001] The invention is an open-loop digital baseband pre-correction method applicable to various digital audio and video broadcasting systems, in particular to an open-loop digital baseband pre-correction method based on polynomial fitting technology for amplitude and phase distortion. Background technique [0002] As we all know, digital audio and video broadcasting system (DAB, DRM and DVB) signals using OFDM modulation technology have a very high peak-to-average ratio, so the requirements for the dynamic range and linearity of the subsequent signal processing unit are very high. However, the dynamic range and linearity of the actual modulator, frequency converter and power amplifier are limited, especially the final RF power amplifier (HPA), due to the constraints of cost, volume and power supply efficiency, usually the nonlinear distortion is relatively high. serious. Generally, AM / AM (amplitude distortion) and AM / PM (phase distortion) are used to measu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L25/49H04H20/00
Inventor 曾志斌李栋孙象然吕锐杨占昕
Owner BEIJING BEIGUANGKE DIGITAL BROADCASTING TELEVISION TECH
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