Method and device for phase error correction

Abstract

One embodiment of the invention discloses a device and a method of phase error correction, comprising: a phase discriminator, used for latching a controlled phase position sent by the numerical controlled oscillator when a line synchronizing signal and a field synchronizing signal arrive, and comparing with the moment reference phase position, and outputting phase error; a loop filter, used for receiving the phase error sent by the phase discriminator, performing low-pass filtering, and obtaining a frequency control word signal; a numerical controlled oscillator, used for receiving the frequency control word signal sent by the loop filter, generating controlled phase signal, wherein, the phase signal is transmitted to the phase discriminator, and the high position part of the phase signal is transmitted to the lookup table; a lookup table, used for obtaining a quantized value of corresponding sine and cosine functions according to the high position part of the phase signal. The invention eliminates long term accumulation of DDS to frequency quantized error in a complex video signal coder, cuts the phase error with large granularity into uniform phase error with small granularity, and distributes the phase error uniformly on the time.

Description

technical field [0001] The present invention relates to the field of communication technology, in particular to a method and equipment for correcting phase errors. Background technique [0002] DDS (Direct Digital Synthesis, Direct Digital Synthesis) is a key technology used in CVBS (Composite Video Baseband Signal, Composite Video Baseband Signal) digital encoder, which can directly generate chroma quadrature amplitude modulation in the digital domain. Waveforms of the chroma subcarrier sine and cosine functions. [0003] The principle structure of DDS is as follows figure 1 As shown, calculate the ratio of the analog frequency of the sine function and the cosine function to the clock frequency to obtain the digital frequency. The digital frequency is usually a real number with infinite precision, which can be converted into a digital frequency in binary form after quantization. In each clock cycle, DTO (Discrete Time Oscillator, discrete time oscillator) accumulates the...

AI Technical Summary

Problems solved by technology

The phase-locked loop cannot immediately eliminate the phase step generated by the encoder DDS, on the contrary, under the impact of this phase step, the phase-locked loop will temporarily break away from the phase-locked state

When the decoder chroma subcarrier recovery PLL cannot accurately track the chroma subcarrier phase, in the decoder chrominance demodulation circuit, the two color difference signals will crosstalk each other, resulting in at least at the beginning of each line and each field There will be cross-color phenomenon in some parts

Therefore, the existing technology does not really solve the frequency error problem caused by the finite word length effect of DDS, but only converts the resulting bright color crosstalk problem into the mutual crosstalk problem between two color difference signals

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