| 摘要 |
<p>PURPOSE:To accept multiple access from plural terminals by connecting the side of a bus connected to a network terminating device directly to the opposite side, and connecting a frame synchronizing signal for a transmitted signal to the bus line by utilizing a frame synchronizing signal added during the transmission of a received signal. CONSTITUTION:Only the received signal containing the frame synchronizing signal F is sent from the network terminating device 1 to an R line 2 and transmitted to respective terminals 4. This received signal is sent back to a T line 3 at the tip of the bus and transmitted toward the device 1 through the T line 3. Here, a terminal 4 extracts only the signal F from the T line 3. This signal F withstands long-period transmission since its frequency component is low and also allows easy stable timing extraction because the signal is periodical. Each terminal 4 attains multiple access of a transmitted signal containing no frame synchronism to a time area which is made free previously synchronously with the frame synchronizing signal obtained from the T line 3. Then, the device 1 performs timing extraction from the received signal which is sent back at the reception point of the T line 3 to establish frame synchronism and then receives the transmitted signal from the terminal 4 which is put in phase with said synchronism.</p> |
