| 摘要 |
PURPOSE:To identify the signal of the high definition television signal compatible with the existing system by forming a difference signal between a signal series being the result of sampling a subcarrier mu0 and a signal retarding the said signal to have a phase difference pi and checking the period of the difference signal. CONSTITUTION:The signal of subcarrier mu0 is sampled at sampling points of X0, X1, X2, ...by using a sampling frequency of 4fsc. Then a difference signal is generated, the phase of the subcarrier mu0 of which differs, e.g., from pi at the sampling points. In figure, since the point X10 gives a phase difference pito the point X0, the signal series of Xi-Xi-10 is formed at the sampling points of Xi, Xi-10. The absolute value binarizing that level 1 is given to a level exceeding a threshold value + or -DELTATh and 0 level is given within + or -DELTATh is applied and the signal subject to absolute binarization has a periodic pattern 0 takes place once per 10-sample. The presence of the subcarrier mu0 is detect by detecting the period of the signal subject to absolute binarization.
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