Showing papers on "Loopback published in 1983"

Loop transmission system and method of controlling the loop-back condition thereof

Abstract: A loop transmission system and a method of controlling the loop-back condition thereof. The loop transmission system comprises a plurality of node stations, a supervisory station, and two duplicate loop transmission lines which transmit signals in opposite directions. In the loop transmission system, the supervisory station first sends out loop-back commands via both of the duplicate loop transmission lines when faults are detected on both of the duplicate loop transmission lines at the same time. Each of the node stations establishes a loop-back path while retaining a connection path to a succeeding node station upon the receipt of a loop-back command. The loop-back path is released only in the node stations which receive signals normally from both of the duplicate loop transmission lines when the supervisory station sends release commands to the node stations after sending the loopback commands.

Data transmission device for loop transmission system

Abstract: A loop transmission system is disclosed which, on the failure of a transmission path in an active loop or transmission paths in both active and back up loops between adjacent transmission devices, automatically switches all the transmission devices from one of the loops to the other, without observing any particular transmission device, so that the whole system is capable of reconstructing a new loop. A faulty portion is located and a loop back configuration is set up excluding the faulty portion.

Data bridge with gating and/or testing

Abstract: A communication bridge joining a primary communication channel to a plurality of secondary communication channels has electrically operated switches in series with the respective ports to the secondary communication channels. Control signals applied to the primary channel are utilized to address the bridge and to selectively drop or add secondary ports. Additionally a loopback circuit can be connected and disconnected in the primary port.

Relieving method for system down in a loop type data highway system

Abstract: PURPOSE:To relieve normal stations surrounded by a disconnected transmission line, a back amplifier in a down station and plural down stations by using both loop back and by-pass systems. CONSTITUTION:A remote station inputs signals sent through the 1st and 2nd transmission lines to receivers 121, 122 through by-pass change-over switches 111, 112 respectively and these received signals are inputted to a data processing device 14 through a loop back circuit 13. A data output from the device 14 is taken out from transmitters 151, 152 through the circuit 13 and these output signals are sent to the transmission line side through by-pass change-over switches 161, 162 connected to the switches 111, 112. Disconnection generation and restoration detecting circuits 171, 172 controls loop relief at the time of disconnection.

Selecting circuit of received signal

Abstract: PURPOSE:To reduce the cost by switching and using one loopback noise eliminating filter for plural switched capacitor filters. CONSTITUTION:One of n-number of kinds of a received signal is inputted to an input terminal 1 selectively. Meanwhile, a discriminating signal is inputted to a switching control part 11 through a control signal input terminal 12. The switching control part 11 switches a switch 6 synchronously with an inputted discriminating signal so that the corresponding switched capacitor filters 31- 3n are loopbacked and are connected to a noise eliminating filter 4.

Loop transmission system

Abstract: PURPOSE:To prevent system-down by providing a clock generating circuit and a supervising circuit to each of terminal station devices connected to a loop transmission line to constitute entirely the system identically thereby allowing any of the devices to be operated as a master station if a failure occurs. CONSTITUTION:Nodes 1...n are connected in a ring by two systems of loop transmission lines L1, L2 of optical fiber constitution. The nodes 1...n are constituted by a basic section F of the same structure, the loop transmission lines L1, L2 and an interface section PI/0 connecting the terminal devices. The basic section F has an LBC (loop back control) circuit performing such as switching of a transmission terminal device, detection of failure, transmission of a detection signal, generation of a clock signal or the like, and an MPU (microprocessor unit) extracting the own data from a multiplex signal and connecting and controlling the transmission and reception data from the terminal devices.

Transmission control system for data highway

Abstract: PURPOSE:To perform loop back by means of line changeover at each node in case of a line failure, by using each loop individually at normal state, in a multiplex loop transmission system. CONSTITUTION:Switches are selected as shown in Figure normally and data transmission and reception are done individually in the transmission path A, the same as the transmission B, terminal B1 switch 8 receiver 9-2 switch 7-1 transmission line controller (a plurality of data transmission and receivers are connected to the controller and they perform communication through the controller) 6-1 switch 7-2 driver 10-1 switch 8 terminal B2. In case of the line failure, the direction of transmission of the line B is inverted by switching the switch 8, and the loop back is done for a node adjacent to the failed point by selecting the position of the switch near the failed point out of the switches 7-1 and 7-2.

Remote-control signal of optical loopback for supervision of long-haul fiber-optic undersea cable systems

Abstract: A remote-control signal for repeater supervision to be used in a remote-controlled optical loopback method of a long-haul optical undersea cable system is proposed on out-of-service basis and the results of its transmission experiment by a field trial system are theoretically analyzed. The remote-control signal is basically composed of a pseudo-random sequence with a periodicity corresponding to a repeater selection frequency. 500 repeater selection frequencies will be available using a monolithic crystal filter (MCF) as a detection filter. By a field trial experiment, the controllability was shown to be maintained even at a bit error rate (BER) of up to 10-1with a control signal level which, being decreased by 1.9 dB, is still more than 30 dB over a filtered noise level due to random bit errors.