| 摘要 |
PURPOSE:To simplify the system constitution by connecting an upper protocol to a carrier band transmission line via a medium attachment unit MAU and providing a collision detecting circuit to the MAU so as to detect the collision of signal on a carrier band transmission line. CONSTITUTION:The high-order protocol is connected to a carrier band transmission line of the information transmission system via plural MAU5. A modulator 11 of each MAU5 modulates a base band signal from the protocol into a carrier band signal and transmitted to a transmission line from a transmission amplifier 13. The signal modulated from the transmission line is received by a reception amplifier 14, demodulated into the original base band signal by a demodulator 16 via a BPF15 and fed to the protocol. Further, the collision detecting circuit 17 detects the collision on the transmission line depending on the reception signal level and the result of detection is outputted to the protocol as a display output. Then the collision of the signal modulated by a carrier band signal is detected simply and surely at a zero level or a level close to double level of the beat signal. |
