| 摘要 |
PURPOSE:To facilitate the handling of a data transmitter even when high-level technique and qualification are absence by specifying the transmit signal of the data transmitter within a specific band without the intervention of an operator and thus reducing the operation contents of the operator as well as the mass. CONSTITUTION:When a data input signal contains a high-frequency signal to be cut off, the signal (e.g. >= about 30MHz) passes through a high-pass filter 11 and is applied to a detector 12. A switch circuit 13 cuts off the data input signal when a detection current supplied to a control terminal attains to some specific value. When the detection current is smaller than the specific value, the switch circuit 13 allows the data input signal to pass and supplies it to an OR gate 14. The data input signal having the high-frequency component cut off is obtained from the switch circuit 13 and supplied to an OR gate 14 to limit its amplitude. A logical gate for a digital circuit such as the OR gate consists of transistor- transistor logic or emitter-coupled logic, so the amplitude of the input signal is limited to a specific value. |
