Image data decoding method of image vertical blanking interval and a device thereof

An image data decoding device of an image vertical blanking interval (VBI) comprising:

• an analog-to-digital converter (ADC) following a sampling clock signal to sample and digitize an analog image signal and then to output the digitized image signal;
• a level adjuster connected to an output terminal of the ADC to remove a blanking level and a signal carrier of the digital image signal, so as to convert the signal to an AC (alternating current) signal without a DC (direct current) level
• a delay circuit coupled to an output terminal of the level adjuster for storing digital data of a teletext data line, which is regulated by the level adjuster;
• a data extractor coupled to an output terminal of the delay circuit for determining the data of the delay circuit and extracting the data of the VBI and then outputting a phase adjustment value;
• a phase accumulator coupled to an output terminal of the data extractor to adjust an accumulated phase with the phase adjustment value output by the data extractor and to feedback to the data extractor to compose a closed circuit with the data extractor, to reduce phase error;
• and
• a memory coupled to the data extractor for storing the decoded bit data.