| 摘要 |
<p>PURPOSE:To attain sure detection of output interruption without increasing an output amplitude by providing a line having 1/4 wavelength in length to output section of an output circuit to detect the output interruption at both ends. CONSTITUTION:A line 12 having lambda/4 (where; lambda is the wavelength of an output signal) in length is connected to the output section of an output circuit 11 and signal interruption detecting circuits 13, 14 are connected respectively to both ends B, C of the line 12. The outputs of the circuits 13, 14 are inputted to an AND circuit 15. An output signal of the circuit 11 is transmitted to a transmission line 16 via the line 12, and the phase is inverted at an open end 17 and reflected. Thus, the amplitude of the signal is minimum at a point of n.lambda/2 from a receiving end 17 and maximum at a point of n.lambda/2+lambda/4, and the amplitude of signal at one of the points B, C is larger than the amplitude of the output signal. In case an output is transmitted normally from the circuit 11, one of the outputs from the circuits 13, 14 is at L level. If the output of the circuit 11 is low abnormally, the outputs of the circuits 13, 14 both go to H level and the alarm at H level is transmitted from the output of the circuit 15.</p> |
