| 摘要 |
PURPOSE:To detect securely whether there is a transmission signal arriving at the input terminal of each data transmitting station from another station or not even when a transmission signal attenuates on a transmission line, by detecting whether a collision between transmission signals occurs on the transmission line or not. CONSTITUTION:For example, the transmission control circuit 3 of a station 10 outputs a transmission command for a data signal which is applied with pulse code modulation (PCM) and addressed to another station at time t1 as shown in the figure (a). A transmitter 4 sends out a data signal having the same waveform with the figure (a) to the transmission line 1 on the basis of the transmission command signal with the slight operation delay of the transmitter 4. Further, the transmission command signal is applied to a delay circuit 8 having a set delay time tau corresponding to the sum of the operation delay time of the trasnsmitter 4 of the station 10 and the operation delay time of a transmit signal detector 11, and this delay circuit 8 applies a signal having the same waveform as the transmit signal from the station 10 as shown in the figure (b) to one input terminal of an exclusive OR gate 9. |
