| 摘要 |
PURPOSE: An apparatus for detecting a NTSC co-channel interfacing signal in a digital TV is provided to stably detect the NTSC co-channel interface without detecting a vertical synchronizing signal and regardless of a channel environment. CONSTITUTION: An apparatus for detecting a NTSC co-channel interfacing signal in a digital TV having a complex number multiplication unit(105) comprises a frequency phase locked loop for controlling a frequency and a phase of an I and Q signal output from the complex number multiplication unit, a numerically controlled oscillator(107) for changing a generating frequency in a desired range based on a central frequency of a Y signal according to a signal from the frequency phase locked loop, an integral portion(108) for integrating the signal from the frequency phase locked loop, and a detecting portion(109) for comparing a signal integrated in the integral portion with a predetermined value and detecting whether the NTSC co-channel interfacing signal exists. In the apparatus, if the signal is larger than the predetermined value, the detecting portion outputs a signal showing the NTSC co-channel interfacing signal exists.
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