Color carrier frequency difference estimation method based on phase unwrapping and linear regression

Abstract

A color carrier frequency offset estimation algorithm based on phase unwrapping and linear regression is disclosed, (1) providing the initial phase of color synchronized component of initial black level signals in a filed; adopting the black level signals at an initial place in the filed; the phase range obtained by the phase estimation being from 0 to 2Pi, there being five phases as frequency estimation; (2) using a phase unwrapping algorithm to unwrap the extracted phase; the phase unwrapping is that the phase at other four lines is adjusted in an unique linear range based on the phase at the first line; (3) using a linear regression model to fit the unwrapped phase, thereby extracting color synchronous frequency; determining the solutions of overdetermined equations by means of least square criterion; (4) using a limitr to limit the extracted color synchronous frequency. When the input is non-standard video signal, the color carrier frequency is estimated by means of the phase unwrapping algorithm and the linear regression model so as to improve the precision of the local color carrier and carry out digital high-definition demodulation.

Description

1. Technical field [0001] The invention relates to the technique of extracting the frequency of the color carrier synchronous signal by using phase unwrapping and linear regression. In particular, it relates to a method for estimating color carrier frequency difference in a digital video decoding system. 2. Background technology [0002] The purpose of video decoding is to decompose the full TV signal into five component signals of R, G, B, line synchronization and field synchronization for display on a TV or monitor. In order to obtain color signal components, it is necessary to restore the local color carrier through the color burst signal. When restoring the color carrier, the usual method is to use an analog color carrier phase-locked loop or a digital signal processing method. Among them, the analog phase-locked loop method has been gradually replaced by the digital method due to many factors such as complex components and large volume. The digital recovery system ha...

AI Technical Summary

Problems solved by technology

The implementation of the digital color carrier phase-locked loop is more complicated, and there are requirements for the sampling frequency, which needs to be close to the integer multiple of the color carrier frequency, otherwise the digital phase detection will be wrong, so for the non-integer multiple sampling signal, it needs to be resampled to The digital color carrier phase-locked loop can be used only when the signal is sampled at an integer multiple. In addition, when there is a large frequency difference, the phase-locked loop needs several frames to track the change of the color carrier; the open-loop method uses a correlation algorithm for each line Precise phase identification of the color synchronization to restore the local color carrier in phase. Since the frequency of the color carrier of conventional TV signals is relatively stable and is very close to the nominal value, the nominal value can be used directly without tracking the frequency when restoring. However, for non-standard signals, the color carrier frequency will have a large offset, and the open-loop demodulation will produce a certain color distortion

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