TEXT BROADCAST JUDGING CIRCUIT

摘要

To judge the text broadcast type of data superimposed on the television signal and transmitted, bandpass filters corresponding to the respective text broadcast types are needed, thereby increasing the circuit scale. To prevent a judgment error, the set level of the level comparing circuit must be set with high precision. Zero cross point data is detected from sampling data (103) generated by digitizing data (101) superimposed on the television signal and transmitted and the slice level (105), and the CRI frequency (114) is computed. The type of text broadcast is judged from the CRI frequency (114). Thus, the CRI can be detected with high precision. Without providing any bandpass filter corresponding to the text broadcast type, the text broadcast type can be judged with high precision. Consequently, a text broadcast judging circuit adapted to all the text broadcasts in the world can be realized with one system.