| 摘要 |
PURPOSE: To provide the abnormal operation preventing circuit which initializes the operation sequence of a circuit on detecting an out-band output signal being almost generated owing to abnormality in a transmission equipment. CONSTITUTION: An IFFT circuit 3 is placed in operation at a sample clock frequency exceeding a modulated wave signal band, an input signal is set to 0 nearby a terminal of (N/2)th order where the Nyquist frequency of an IFFT circuit of Nth order (N: 2 to (m)th power, (m) plus integer) is generated to prevent frequency output nearby the Nyquist frequency, and monitors 8, 9, and 10 are so set as to monitor the level of frequency spectrum of almost (N/2)th degree, and the IFFT circuit generates a frequency demultiplex signal with a digital input signal supplied to a terminal of 0th order-almost a terminal of (N/4)th order and when a monitor detects a frequency component above a specific value nearby the terminal of (N/2)th order, the operation sequence of the IFFT circuit is initialized. |
