Showing papers on "Loopback published in 1986"

Programmable data-routing multiplexer

Abstract: A multiplexer for use in a digital subscriber controller having a number of analog ports and digital ports which can be programmed via an external microprocessor to establish time-division multiplexed bidirectional data paths between three subscriber-selected ports designated as "sources" and three subscriber-selected ports designated as "destinations". Among the ports is a line-interface port having two 64 kilobit-per-second channels on which analog/digital data is received from and transmitted onto the network transmission line. Among the digital ports is a three-channel serial port and a two-channel microprocessor interface port. An analog port is also provided at which a variety of audio transducers may be connected. The data-routing multiplexer consists of three sections, each comprising a plurality of registers connected to a single internal bus on which time-division-multiplexed signals are generated and received by particular subscriber-selected registers, each register within a section serving as either a generator or a receiver for the internal bus for a particular digital channel. An extension of the internal bus is connected to the analog port. A set of three control registers stores the subscriber-selected sources and destinations. Control signals are generated therefrom which affect the subscriber-selected interconnection of registers within the data-routing multiplexer with the internal bus. The multiplexer facilitates maintenance and testing of the digital subscriber controller by permitting a loopback path to be established for a device connected to a port by simply designating a path having that port as both its source and destination.

Data station termination circuit

Abstract: A data station termination circuit for connecting a four-wire, voice frequency transmission facility to either a four-wire or two-wire subscriber station in a telephone communication system for effecting a four-wire or two-wire mode of operation includes a gain/loss network coupled to a receive-in port for receiving incoming voice frequency data signals from a first signal transmission path of the four-wire transmission facility and for amplifying or attenuating the incoming voice frequency data signals. The gain/loss network is formed of a single operational amplifier, a set of binary weighted resistors, and a plurality of single-pole, single-throw slide switches. Other features disclosed include a battery back-up for use during a loopback condition and an optional equalization network for use in a second signal transmission path.

Subscriber line test equipment

Abstract: PURPOSE:To test the normality of a subscriber line from an overall service digital control network terminal side by providing a loopback path on an exchange, sending a test data pattern and comparing the sent pattern with the reception pattern. CONSTITUTION:An incorporation servic digital control network(ISDN) terminal(IST)1 is connected to an ISDN subscriber line test equipment 6 via an information receptacle 7. A path between a loopback trunk 13 of a digital exchange and a digital line 11 in the equipment 6 is set based on a signal sent from a B-channel interface section (DPG/C)3 by the key entry of a signal input/display section 14. In sending a test pattern from the DPG/3 by the equipment 6 succeedingly, a test data pattern is returned to the equipment 6 via a set loop bus. The DPG/C3 receives it and collates the coincidence between the transmission pattern and the reception pattern. A control section 5 displays the result of collation on a display section 14. Thus, the normality of the subscriber line is tested.

Optical data transmission equipment

Abstract: PURPOSE:To easily increase a node with different transmission frequency bands by independently and physically being actually equipped with a transmission means and a receiving means for an active type transmission line and a transmission means and a receiving means for a preliminary type transmission line respectively. CONSTITUTION:An active type optical receiving module 203 and a preliminary type optical receiving module 205 are loaded to an optical board 0 and an active type optical transmitting module 104 and a preliminary type optical receiving module 206 are loaded to an optical board 1 respectively. When a node with different transmission frequency bands is increased at the right side, communcation is executed by the loopback by using the active type optical receiving module 203 and the preliminary type optical transmission module 205, and then, the optical board 1 can be replaced to the board for different transmission frequency bands.

Line check device of automobile telephone base station

Abstract: PURPOSE:To attain normal talking between a base station and other location and to conduct the line test by providing a line switch having a signal loopback function and a wired line connector having a signal loopback function of a wired line of the base station to a mobile set. CONSTITUTION:In conducting the line check, when a test signal from a control section 21 of an automobile telephone exchange station is transmitted, the test signal enters a transmitter 4 through a private line 3 and a wired line connector 14. The test signal is transmitted from the transmitter 4 in a transmission frequency fT, received by a radio equipment main body 17 of a mobile set through a directional coupler 15 and a duplexer 16, the signal goes to a voice band frequency signal, which enters a line switch 18. In checking private lines 3, 8 the connector 14 is activated by using a loopback control signal from a base station control section 26 receiving the control section 21 to apply the check of the control section 21 and lines 3, 8.

Transmission control system

Abstract: PURPOSE:To prevent the relief of a network from being disabled because of disabled constitution of loopback due to a fault of a main transmitter (loopback) by providing plural transmitters outputting a check signal while changing each direction in the network through duplex transmission lines. CONSTITUTION:An active link 1 and a standby link 2 are set so that the progressing direction of a transmission signal is reversed as shown in the arrow. Signal selection switch circuits 3, 4 send some signals to the links 1, 2 switchingly. Separate selection command signals (a, b) are inputted to the link switches 3, 4 from a selection control circuit 7 and any of a transmission signal received from the active link 1, a transmission signal received from the standby link 2 or a test signal C generated from a test signal generating circuit 8 is selected by the link switches 3, 4.

Data line loopback test method

Abstract: PURPOSE:To attain automatic loopback test even between MODEMs having different communication speeds by providing a speed change means changing the speed of input data into a prescribed speed and discriminating the input data into a modulator-demodulator. CONSTITUTION:In case of a V.27 type MODEM3, a multiplier circuit 11 is added and a frequency division circuit 12 of frequency dividing ratio 3/16 is provided. When a loopback command (2) is inputted to a MODEM transmission/reception circuit 6'' from a MODEM (V.29 type), a baud rate signal (4) of 1,600 Bauds is multiplied three times at once by the multiplier circuit 11, frequency-divided in the frequency dividing ratio of 3/16 at the frequency division circuit 12 and a signal (5) having a communication speed of 300bps is outputted to a data discrimination circuit 8. On the other hand, a loopback command (2') having a communication speed of 300bps is fetched to a data discriminating circuit 8'' from an output of the MODEM transmission/reception circuit 6'' and a data discrimination circuit 8'' discriminates it that the loopback command (2') data is a loopback command at the MODEM3 from the input of the same communication speed to start a loopback control circuit 7''.

Remote loopback method

Abstract: PURPOSE:To attain loopback control with simplicity and high reliability by using a pulse train continuous for a prescribed period in a pulse period shorter than the pulse period of a transmission signal as a loopback control signal. CONSTITUTION:A loopback control signal (b) is generated in an MODEM of own station to form a loopback in the opposite MODEM. The control signal (b) consists of a continuous pulse of a prescribed length in a period sufficiently shorter than the pulse period of a transmission data (a). The loopback control signal (b) generated in this way is transmitted to the opposite MODEM while being incorporated in a transmission signal (c). The opposite MODEM detects the control signal (b) to generate a reflected loop. The data signal (a) in the transmission signal (c) succeeding to the control signal (b) is reflected to the own station MODEM by using the reflected loop.

Keyboard connecting system

Abstract: PURPOSE:To specify a fault generating point even by the user by applying loopback in a keyboard controller to specify which of the keyboard controller and a keyboard device has a fault generating point. CONSTITUTION:A loopback circuit control section 6 sets from a set line 17 from a command section 5 to actuate a loopback circuit section 15. Data subjected to serial conversion is received by the reception section of a serial/ parallel converting circuit 7 again via a loopback circuit section 15 by setting the loopback test data to the transmission section of a serial parallel converting circuit 7. A main controller 1 reads data of the reception section of the circuit 7 subjected to parallel conversion and compares the data set to the transmission section. As the result of comparison, when they are coincident, the keyboard controller 2 discriminates it as a normal state. When dissident, it is discriminated that the keyboard controller 2 has a fault.

Loopback control system

Abstract: PURPOSE:To stabilize the system while holding the loopback constitution by transmitting a constitution holding signal from a central station device to each terminal station when single loop reconstitution is made by a terminal loopback control due to both terminal station system-down. CONSTITUTION:If both systems of terminal stations TDS2 are in system-down, both adjacent stations detect a fault of optical reception, apply loopback control then the system is subject to a reconstitution loopback by a system control section SYS to constitute a stable single loop as shown in broken lines. The system control section SYS transmits the constitution holding signal to a specific control channel on both system optical loops via central control sections CSCTL0, CSCTL1 to keep stably the loopback constitution, thereby preventing the effect of temporary restoration.

Digital subscriber line test system

Abstract: PURPOSE:To attain the transmission test of a digital subscriber line by providing a loopback section and an identification section in a line terminator and eliminating a loopback loop formed by the loopback section when the data transmission- enable state is identified by the identification section. CONSTITUTION:The loopback section 5 an the identification section 6 are provided in the line terminator 4 connected to a test device 8 via an exchange 1, a subscriber circuit 2 and a digital subscriber line 3. The loopback section 5 forms a loopback loop in the circuit 2 and when the data transmission in enabled, the identification section 6 eliminates the loop. That is, in conducting the transmission test of the digital subscriber line, the test data from the device 8 or the like is subjected to loopback by the loopback loop formed by the section 5 until the data transmission is attained at first for the transmission test of a subscriber line 3. When the identification section 6 identifies the data transmission-enable state, the loopback loop is eliminated and conventional data transmission is attained by a terminal 9. Thus, the transmission test of the digital subscriber line is attained within the loopback loop forming period.

Time division multiplex line loop back test method

Abstract: PURPOSE:To attain test by a conventional exchange processing procedure by using an exchange means provided to a time division multiplex line trunk or an adaptor so as to exchange a test channel and apply loopback. CONSTITUTION:A loopback circuit 21 or buffer memories 15, 16 are provided with a means exchanging a specific time slot, and no loopback circuit 21 connecting time division multiplex lines 19, 20 is formed in a conventional talking processing and no exchange between specific time slots is conducted. At the loopback test, the time division multiplex lines 19, 20 are connected by a U link to form the loopback circuit 21. When a start signal to an opposite exchange is transmitted from an interface circuit 17 to the line 19, it is inputted to an interface circuit 18 via the loopback circuit 21 and exchanged into other time slot at a buffer memory 16, then a channel receiving the start signal transmits a response signal and the loopback test is conducted by the conventional exchange processing procedure.

Transmitter having loopback processing function

Abstract: PURPOSE:To attain a loopback test to each individual line by allowing a procedure supervisory section to eliminate apparently generation of an event against the limit condition and to transfer the collected reception data to a terminal device during the loopback test in a transmitter using two lines in parallel for transmission. CONSTITUTION:When it is supposed that the loopback of a line 8 is made effective, a transmission distribution control section 11 applies nearly all transmission data to a loopback forming section 12-1. Thus, the transmission loopback is formed by a route 19-1, a loopback forming section 15-1 and a reception multiplex section 16. Further, the reception side loopback is formed by an interface section 14-1, a loopback forming section 15-1 and a route 20-1. While the loopback test is conducted, the procedure supervisory section 17 transmits the loopback data to a terminal device 2 as reception data by taking the following countermeasure that it is regarded that no error takes place at the terminal device 2 even if violation of the limit condition takes place in the procedure.

Automatic fault excluding system

Abstract: PURPOSE:To decrease the recovery time by providing an automatic constitution controller provided with a bypass mechanism and a ring monitor mechanism to each ring station of the ring communication system so as to exclude automatically a fault not separated by itself. CONSTITUTION:A master side loopback device LU and a slave side loopback device LL are connected to the main and sub feeders of the ring communication system via optoelectric and electrooptic converting circuits 1, 2, 3, 4 of the automatic constitution controller OLUi. further, the ring monitor device M is connected to the device LL and buffers 11-14 connecting the bypass devices 16-19 and the bypass devices 16-19 connected to ring stations RS1-RS4 are provided between the devices M and LL. Further, a system block source 5, a microprocessor 6, a ROM7 and a RAM8 are connected to the device M. Then a fault not separated by the stations RS1-RS4 themselves is excluded automatically by the device OLUi to detect automatically the faulty part thereby decreasing the recovery time.

Transmission synchronous controller

Abstract: PURPOSE:To restore the device in a short time when a fault takes place by inserting an intra-office loopback test burst for intra-office supervisory in a form that each participation station synchronizes with a substantial satellite line network and supervising continuously the transmission fault of the own station at line operation. CONSTITUTION:A transmission frame timing generating circuit 11 uses a reception frame timing signal S1 to establish a satellite system transmission time division multiple access (TDMA) frame, a transmission frame timing signal S2 of the satellite system is generated and outputted to a burst transmission timing generating circuit 12. A propagation delay correction circuit 21 corrects an offset D0 and an offset D1 connects to one input of an intra-office transmission frame timing generating circuit 22. An intra-office burst transmission timing generating circuit 23 inputs a transmission line plan S6 of the intra-office loop system (not shown). The circuit 23 has a counter synchronously with the transmission frame timing signal S6 of the intra-office loop system having a period of 1 TDMA frame, when the location on the transmission frame commanded by the transmission line plan S6 of the intra-office loop system and the count are coincident, the burst transmission timing signal S7 of the intra-office system is outputted to a transmission burst generating circuit 32 via an OR gate 31.

Detector of transmission line loopback state

Abstract: PURPOSE:To prevent malfunction by adopting the constitution that a specific code is transmitted respectively to incoming and outgoing transmission lines and the reception side separates and extracts the said specific code for identification so as to detect that the transmission line is in loopback connection state. CONSTITUTION:A main signal and the 1st code W transmitted from a station A to an outgoing transmission line in normal connection state are transmitted through the outgoing transmission line and a relay station and received by a station B. The 1st code W is separated and extracted for identification and it is discriminated that the system is in the normal connecting state. When a loopback command is given from the station A to the relay station C, the relay station C applies loopback connection to the incoming/outgoing connection. In this case, the 1st specific code W transmitted from the station A to the outgoing transmission line is transmitted from the relay station C while being subject to loopback into the incoming transmission line and detected by the reception section of the station A. The reception part of the station A discriminates that the reception signal is a loopback signal because the specific code is the 1st code W.

Loop form local area network

Abstract: PURPOSE: To miniaturize the transmission delay to improve the reliability by applying the communication between terminals connected to the transmission line via a double loop transmission line of the shortest distance, dividing the time slot constituting the time division multiplex frame into two regions on the line and assigning the result to each of the lines. CONSTITUTION: One time slot is divided into two regions, a slot 72 is assigned for the system 1 and a slot 73 is for the system 0. In the case or two-way communication between terminal equipments 3a, 3b, nodes 2a, 2b use a terminal interface section 28 to select the lines #0, #1 of the systems 0, 1 for communication so as to minimize the communication delay between terminal equipments. If a fault takes place in the line, then the nodes 2a, 2b change over each matrix switch 25 so that the outgoing line of the line #0 is subjected to loopback to the incoming line of the line #1 and the outgoing line of the line #1 is subjected to loopback to the incoming line of the line #0 respectively. Thus, the signal of the system 0 from the terminal equipment 3a is given to a terminal equipment 3b via a line #1 and the signal of the system 1 from the equipment 3b reaches the terminal equipment 3a via the line #0. COPYRIGHT: (C)1987,JPO&Japio

Test system of synchronous type line control circuit

Abstract: PURPOSE:To facilitate a loopback test by synchronizing a signal in a transmission timing sent by a transmission timing sending setting means when a line loopback setting means applies loopback test to a MODEM interface signal of a line control circuit. CONSTITUTION:An interface signal (a) sent from a line interface circuit 9, that is, a transmission data SD, a transmission request signal RS and a transmission synchronizing timing ST1i are reflected by an external connector (b) to apply function test as a reception data RD, a transmission permission signal CS and a reception timing signal RT. The timing signal ST1i is reflected at a terminal TEST for ground of a terminal FG, a level of a setting terminal A of a resistor R is suppressed to OV, an AND circuit 11 sends the timing ST1i to a NOR circuit 13 and the timing ST1i is sent to a terminal ST1 via a NAND circuit 16.

Radio station equipment

Abstract: PURPOSE:To simplify the operation, to attain miniaturization and economy by using a transmission shutter and a reception shutter. CONSTITUTION:In closing a transmission shutter 9 at intra-station loopback test, a transmission signal from a transmitter 6 is reflected by a transmission shutter 9, terminated by a terminator 4 through a circulator 8 so as to keep the load condition of the transmitter 6 nearly in the normal operating state. In closing the reception shutter, a reception signal from an antenna 1 is reflected in the reception shutter 2 and not inputted to a receiver 5. Thus, the intra- station loopback test is conducted without giving effect onto an opposite radio station or an opposite communication satellite.

Synchronization establishing system

Abstract: PURPOSE:To ensure the retraining operation by bringing an MODEM of the calling mode at carrier interruption detection into the retraining signal state in advance and sending a training signal before the MODEM of the calling mode. CONSTITUTION:An MODEM 2 is used in the calling mode and an MODEM 3 is used in the incoming mode. When a control section 322 of the MODEM 3 detects carrier interruption, a carrier interruption detection signal is sent to an interface control section 34. On the other hand, the control section 322identifying the divergence of an EQL 323 commands the start of retraining sequence to a training section TRN 311 via the control section 34. A carrier interruption control section 33 also identifies the carrier interruption to control the retraining sequence and sends a null signal Sa before the transmission of the retraining signal S1 and sends the signal S1. When the MODEM 2 receives the signal Sa, the MODEM 2 identifies it as carrier interruption and sends the signal S1 to the MODEM 3. The MODEM 3 identifies the signal S1 to send a loopback signal S1 to the MODEM 2. Thus, the sequence synchronization between the MODEMS 2 and 3 is ensured.

Loop transmission equipment

Abstract: PURPOSE:To improve remarkably the reliability of the entire system by providing the 2nd transmission line transmitting a data in opposite direction in addition to the 1st transmission line transmitting data normally and forming a new loop with the 1st and 2nd transmission lines when a station existing just at the downstream position of an open line fault detects the open line fault so as to continue communication. CONSTITUTION:A CPU 4 controls a transmission/reception switch circuit 2 and an error signal generating circuit 13, an error signal is being outputted during the open line fault from the error signal generating circuit 13 and the signal is transmitted to an upperstream station Ti-1 through a transmission circuit 8 and a transmission line Li-1. Through the constitution above, if an open line fault takes place between stations ST 2 and ST 3, a signal from a transmission line R1 is reflected on the station ST 2 and transmitted in the part of ST2 L1 ST1 Ln - L3 ST3, while the data signal from a transmission line L3 is reflected on the station ST 3 and transmitted in the path of ST3 R3 ST4 - R1 ST2, finally a new loop subject to loopback by the stations STs 2, 3 is constituted to continue the communication.

Loopback extension control system

Abstract: PURPOSE:To attain the automatic extension of a loop and the quick recovery of a communication system by providing a means commanding the maintenance or release of loopback constitution based on the reception state of a signal on the transmission line of a required node after the loopback constitution is set. CONSTITUTION:When the loopback is constituted as shown in the figure, for example, a loopback control section 46 commands loopback setting, e.g., from the system 0 to the system 1 to nodes 34, 35. When transmission lines 41, 43 are normal and both the nodes are recovered, a loopback shown in broken lines is set in both the nodes 34, 35. Then the loopback control section 46 inquires about the state to the end node 36 of the loopback loop and detects that the reception from the outside of the loop is normal, the section 46 commands the loopback release to the node 36 to extend the loop up to the node 34, inquires similarly about the state to the node 34, and when the state is normal, the section 46 commands the loopback release.

Remote loopback system

Abstract: PURPOSE:To prevent forming of a closed loop between opposite stations by inhibiting the transmission of a loopback instruction from the own station when the loopback instruction from an opposite station is received in a system executing loopback mutually to stations opposite to each other. CONSTITUTION:When remote loopback is executed by the loopback instruction from the own station A in the opposite station B, the opposite station B receives the loopback instruction from the own station A, a loopback instruction receiver 6B generates an inhibit signal 9B to control a remote loopback instruction transmitter 4B and to inhibit the transmission of remote loopback instruction. Thus, when the opposite station B is in the remote loopback state by the loopback instruction from the own station A, no remote loopback instruction is transmitted from the opposite station B and the forming of a closed loop is avoided because of the loopback state for both the stations at the same time.

Time division multiplexer

Abstract: PURPOSE:To reduce the time required for the restoration of an error by applying loopback data communication between a terminal interface and a multiplex controller when the error is detected from the check of a redundancy polynomial so as to detect a part having the error. CONSTITUTION:A time division multiplex connects a multiplex control section 6 to plural terminal interfaces 5a-5n via buses 7, 8 and its operation is controlled by a device control section 9. the information from the control section 9 is given to a processor 11 via a buffer 13 of the terminal interfaces 5a-5n. A redundant polynomial calculated by a redundancy polynomial generating section 21 is added to a transmission data and sent to the bus 7. An error of the received data is detected at a redundancy polynomial check section 22 by checking the redundancy polynomial. When the error is checked. loopback data communication is applied between the terminal interfaces 5a-5n and the control section 6 to specify the error occurrence part. Thus, the time required for error recovery is reduced.

Communication system between subscriber's equipments

Abstract: PURPOSE:To eliminate the limit of a quantity between exchange of high speed data by using an S bit area for a data communication enough for a low speed in a subscriber's system having a spare bit area. CONSTITUTION:A network terminator 3-1 is provided with a selection cicuit 8 selecting whether a spare bit is subject to loopback or a line is connected to a subscriber line and subscriber equipments 2-1-1, 2-N-1 have a spare bit control circuit 19 possible for communication using the S bit area. In making communication while using the S bit area, the subscriber equipment 2-1-1 uses a signal CH bit area to transmit an S-bit using request signal and a digital exchange 4 transmits the S bit using signal. This signal is separated by the subscriber's equipment 2-1-1, multiplexed and reaches a subscriber's equipment control circuit 18, the S-bit using enable signal is fed to the spare bit control circuit 19 to attain loopback state for the S-bit area.

Loopback control system

Abstract: PURPOSE: To shorten a loopback time at the time of restoring a fault by constituting the titled system so that a master station calculates the propagation delay time of a carrier wave, based on the number of stages to a slave station for executing a loopback instruction, from constituting information of a network. CONSTITUTION: A master station 1 derives the number of stages of a slave station 2, to the slave station 2 for executing a loopback, from network constituting information in its own station storing the positional relation of the master station 1 and the slave station 2 which are connected in the shape of a loop, calculates the propagation delay time of a carrier wave turned back by the slave station 2 for executing a loopback, from the number of stages of the slave station 2, and repeates to execute a loopback instruction to the next slave station 2, as a loopback failure, in case the master station 1 cannot receive the carrier wave even if the propagation delay times elapses. In such a way, the loopback time at the time when a fault has occureed can be shortened, therefore, a line stop time at the time when a fault has occurred can be shortened. COPYRIGHT: (C)1988,JPO&Japio

Loop back test system

Abstract: PURPOSE:To attain a loop back test of a digital subscriber circuit with an electronic exchange by having collation between a transmitted random pattern and another random pattern received via a network. CONSTITUTION:A central processing unit 1 delivers a loop back command to a line processor 4' when a loop back test is given to a digital subscriber circuit 4. Then the processor 4' sets its own loop back circuit 9 under a return connection state. The unit 1 drives a signal reception/distribution device 2 and controls a network 5 to connect the output of a random pattern transmission circuit and the input of a random pattern reception circuit to a network inter face 11 of the circuit 4 via the network 5. When the unit 1 delivers a loop back test command, a random pattern is returned by the circuit 9 via the inter face 11.

Fault location retrieval system in optical relay transmission system

Abstract: PURPOSE:To retrieve a faulty location even when any terminal station by applying loopback automatically to a repeater of a faulty location and allocating a specific delay to each repeater when a transmission line is faulty. CONSTITUTION:A violent code detector 71a of a repeater 4 detects a violent code due to a fault at a point P to drive a changeover circuit 72 for loopback. As a result, since an input signal of an outgoing transmission line 6b of a repeater 3 does not satisfy a code mark inversion (CMT) code rule, the repeater 3 applies automatically loopback. When loopback is applied in a transmission line at a fault, a reference loopback pulse pattern for measure measurement inputted to a CMI coding circuit of a terminal station 1 is sent to a transmission line 6 by a signal sending circuit as the CMI code and subject to loopback by a delay amount. Then the signal is received by the signal reception circuit of the same terminal station 1 as the transmission and the CMI coding circuit outputs the original measuring pulse pattern. In this case, the time difference between the reference pulse pattern and the reception pulse pattern is read to decide a faulty location.

Test system of frequency synchronization

Abstract: PURPOSE:To attain the test of a line by detecting whether or not a data number in a synchronizing buffer exists between an upper limit and a lower limit value. CONSTITUTION:In testing a line between nodes ND-A and ND-B, an output and an input of a terminal DTEb side of the node ND-B are connected, the test data is transmitted from a terminal DTEa connected to the node ND-A and the terminal device DTEa receives the test data. That is, a loopback line is formed for the test. The test is conducted by the test system like this and the data number in the data speed adjustment buffer built in a multiplex MXa of the node ND-A side is checked to check the operating state of a loopback line.

Collision detection system

Abstract: PURPOSE: To improve the detection capability of collision by connecting a comparison means to a data storage means and a reception section, comparing transmission packet data with loopback packet data to decide the presence of collision. CONSTITUTION: While transmission packet data sent from a terminal equipment 1 to a transmission line 3 via a transmission section 2 is stored in a data storage emans 5, the end of preamble of the loopback packet received by a reception section 4 via the line 3 is detected by a data comparison control means 7 to output sequentially the transmission packet data from the data storage means 5, the output data and the reflected packet data are compared sequentially by a comparison means 6 to detect the collision. Through the ocnstitution above, the send data is compared sequentially with the loopback packet data and if a predetermined relation is not preserved between the data, an output representing the occurrence of collision is sent to the terminal equipment 1. COPYRIGHT: (C)1987,JPO&Japio