Method for digital television emission system to solve distortion of direct frequency conversion I and Q data

Abstract

The invention provides a method for a digital television emission system to solve distortion of direct frequency conversion I and Q data, and relates to the technical field of digital broadcast emission. Steps of the method are that: alignment is performed on data before up frequency conversion and data after down frequency conversion; three groups or more than three groups of uncorrelated sequences are found, and an I and Q equation set is established; the equation set is solved, and an I-path coefficient Ci and a Q-path coefficient Cq are obtained; multiple I and Q signal equation sets are found, arithmetic average is respectively performed on each obtained I-path coefficient Ci and the Q-path coefficient Cq so that an average value of the coefficients is obtained. Adjustment coefficients of down frequency conversion output I and Q signals can be automatically calculated according to changes of the system so that the corrected I and Q values are basically not affected by non-ideal factors existed in up frequency conversion and down frequency conversion, and thus the method has characteristics of being timely and accurate in correction.

Description

technical field [0001] The invention relates to the technical field of digital broadcast transmission, in particular to a method for solving I and Q data distortion of direct frequency conversion. Background technique [0002] In a digital broadcast television transmitter, the peak-to-average ratio PAPR of the excitation signal of the power amplifier is too high, which will cause distortion of the power amplifier, and the exciter is usually required to have the function of adaptive pre-correction. Its implementation must obtain approximately ideal feedback data. If the method of baseband predistortion is adopted, the signal before up-conversion is I and Q, then the signal after down-conversion must be approximately equal to I and Q. However, most of the current digital exciters use direct conversion technology, because the amplitude and phase of the I and Q channels in the up and down conversion are unbalanced, which will generate unnecessary DC and image signals, resulting ...

AI Technical Summary

Problems solved by technology

[0020] When the local oscillators of up-conversion and down-conversion are inconsistent, the I and Q signals output by demodulation will also interfere with each other, so that the real part is aliased with the signal of the imaginary part, and the imaginary part is aliased with the signal of the real part, and the The amplitude and phase changes are all related, that is, the obtained down-converted output cannot be directly restored to be consistent with the original signal

[0021] In the prior art, the correction coefficients for the above-mentioned signal distortions are usually obtained through artificial presets, which cannot be automatically calculated according to system changes, so the purpose of adaptive pre-correction cannot be achieved

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