| 摘要 |
PURPOSE:To detect the start point of an accurate turn-on sequence, by utilizing the character of the turn-on sequence signal having a linear spectrum only at the Nyquist frequency point. CONSTITUTION:Phase inversion signals 1 of 0 deg. and 180 deg. following nonsignal are given to demodulator 2 to obtain the demodulation signal having a linear spectrum only at the Nyquist frequency point. In-phase signal 18 of this demodulation signal is applied to the digital filter consisting of delay circuit 3 and adding circuit 11, and antiphase signal 19 is applied to the digital filter consisting of delay circuit 5 and adding circuit 12. Outputs of these filters are given to square summing circuit 13, and the output level is decided by deciding circuit 14, and energy of input signals 1 is detected to operate level deciding circuit 14 only for the time corresponding to detected energy above by timer 16, thereby obtaining start detection output 17 of the turn-on sequence. |
