Showing papers on "Loopback published in 1992"

Transceiver self-diagnostic testing apparatus and method

Abstract: The present invention includes an apparatus and a method for transceiver self-diagnostic testing in a communication system. A feedback unit (228, 326) is utilized that allows performance of a loopback test independent of a transmit frequency to receive frequency difference without undue proliferation of circuitry.

Testing system for digital transmission lines

Abstract: A testing system for digital transmission lines with a metallic loopback and direct current bypass for use with regenerative repeaters. The Bell telephone network typically includes transmit and receive lines interconnected to a central office. Regenerative repeaters positioned along the lines detect signals and regenerate new signals. The present invention includes a controller, loopback line, and bypass. The loopback line interconnects the transmit and receive lines upon receiving a test activation signal from the controller. The bypass allows direct current to pass through to the rest of the line during a test. Accordingly, when a test of the telephone lines is to be performed, lines will allow the test signal to loop back to the source of origin, but will block the loopback of DC power signals. Moreover, DC power is supplied to the rest of the transmission line, in the same manner as when the testing procedure is not occurring. Moreover, the loopback line is positioned such that the overload protection circuitry is also subject to the performance test.

Method and apparatus for permitting intranework testing of internetwork functions

Abstract: Testing according to this invention allows functions of a first network which is accessible by other networks to be tested without requiring a separate simulator of the other network or interaction with the other networks. This capability is generally accomplished by utilizing a gateway node in the first network to loop-back a query originated in the first network so that it appears as though it originated from another network. The first network then processes the query and originates a reply to the query which is forwarded to the gateway node. Again, the gateway node loops back the reply to the node in the first network which originated the query. Receipt of the loopback reply at the first node provides an indication that the first network can properly respond to queries originated in another network corresponding to the test query.

Optical line monitor

Abstract: A relatively simple, low cost apparatus detects the presence and location of faults in an optical transmission system. It is particularly applicable to underwater optical transmission systems. The optical transmission system contains at least one optical fiber pair extending between two terminals. Optical amplifier based repeaters are located at predetermined positions along fibers. Each repeater has a simple high-loss optical loopback circuit which is used to provide fault identification and location. The loopback circuit couples a portion of the optical signal travelling from a transmitting station through one of the fibers, attenuates that portion of the optical signal, and adds the attenuated signal to the optical signal in the other fiber for return to the transmining station. Fault location is accomplished by launching a supervisory signal into the fiber from one of the terminals. At each repeater, the loopback circuit causes an attenuated version of the supervisory signal to return to the station from which it was launched, combined with any noise and signal in the return lines. The supervisory signal is a pseudo-random word which can be recovered from the signal and noise in the return line via a correlation technique. The loopback circuit in the repeaters is composed of passive components which may comprise a pair of optical couplers each of which is adjacent one of the two transmission fibers. The optical couplers are connected by a fiber containing a preselected amount of attenuation. There is no need for any sensing circuitry in the repeater to activate the loopback in response to command signals in the supervisory signal. The production of the supervisory signal consequently is simplified because there is no need for command information to be a part of the supervisory signal. Degradation of signals through the optical transmission system is easily detected in a reasonable amount of time at the terminals of the system via the correlation technique. In addition, the correlation technique allows one to easily identify the location of the degradation on the transmission line.

Optical loopback tester with air gap attenuator

Abstract: An FDDI loopback connector or optical network is suitable for testing in fiber-to-fiber applications and designed to be interchangeable with a complimentary connector. The loopback tester is afforded a desired level of attenuation by providing a fiber loop having a controlled air gap. Adjustment of the air gap will afford a desired attenuation level.

Segment tester for a repeater interface controller

Abstract: The nodes of a repeater interface controller which repeats data packets received from one segment of a local area network onto the remaining segments of the local area network include loopback circuitry that allow the data packets received from the one segment to be repeated back onto the one segment in addition to the remaining segments of the local area network, thereby allowing the integrity of the one segment to be verified.

Abnormality diagnostic system for loop transmission system

Abstract: PURPOSE:To automatically correspond to multiple fault by smoothly operating, stopping, and restarting the duplexed loop transmission line system. CONSTITUTION:Monitoring nodes A-H are provided in the duplexed loop transmission line system, from which two types of monitoring packets are transmitted to two transmission lines I and J to recognize the state of the both transmission lines I and J. At the fault generation, it is detected in a node unit, and the loopback processing is performed to transfer fault generation information by means of a monitoring packet to monitoring nodes A-H where the generation of fault is recognized based on the monitoring packet information. The monitoring nodes A-H are isolated due to the multiple fault, and even though the transmission line without monitoring nodes A-H are generated, a new one is automatically generated so that the state of the remaining transmission line can be automatically and distributedly monitored.

Rueckfuehrungseinrichtung fuer ein diagnose-untersystem fuer eine entfernte basisstation

Abstract: Radio system infrastructure equipment is provided which comprises base station transceiver equipment 20 for communication with a mobile transceiver and diagnostic transceiver equipment 35 associated with the base station transceiver equipment for generating test signals and feeding them to the base station transceiver equipment A loopback facility is provided within the infrastructure equipment for looping back a signal received from the diagnostic transceiver equipment at a point within the infrastructure equipment This signal is returned to the diagnostic transceiver equipment, where it is tested, for example by comparison with the original signal, and faults are diagnosed The test signal may be looped back from various points so that various parts of the equipment may be tested In order to facilitate a loop back via the public service telephone network 30 without the test signal being cancelled by echo cancellers 31, 32, a maintenance terminal unit is connected to the network 30 and incorporates means for receiving a signal from the network, means for storing the signal, and means for automatically retransmitting the signal to the network after a predetermined delay, (Fig 6)

Mobile station equipment

Abstract: PURPOSE:To provide a loopback transmission line on an information channel during talking with respect to the mobile station equipment in the digital mobile communication system CONSTITUTION:The equipment is provided with a radio interface means 11 sending/receiving user information and control information through a radio line applying time division multiplex transmission to an information channel being a transmission line for the user information and a control channel being a transmission line for the control information relating to the information channel, a demultiplexer means 13 demultiplexing the user information and the control information received from the radio line based on the time division multiplex transmission system, a control means 15 processing the demultiplexed control information and generating transmission control information according to the processing procedure, a user information selection means 17 selecting either the user information or the transmission user information according to the processing result, and a synthesis means 19 synthesizing the selected user information and transmission control information and giving the result to the radio interface means 11 based on the time division multiplex transmission system

Channel continuity test system

Abstract: PURPOSE:To eliminate the need for the connection of a tested subscriber circuit to an external test circuit and to simplify the control of an exchange by confirming the continuity of a channel through the loopback of a test signal in a subscriber circuit. CONSTITUTION:When the subscriber circuit continuity test is executed, an exchange processing unit 3 sends a control signal Sc to a subscriber control section 15 to operate a test connection changeover device 14 thereby connecting a test circuit 13 to a 2/4-wire conversion circuit 12. Moreover, the exchange processing unit 3 controls a time division channel 2 to set a channel from a digital test signal transmitter 4 to the subscriber circuit 1 and to a channel from the subscriber circuit 1 to a digital test signal receiver 5. When the receiver 5 receives the test signal looped back normally, the normality of the continuity of the channel is confirmed and when the test signal is not normally received, it is discriminated that a fault exists in the continuity of the channel.

Communication control system and switching unit used for the same

Abstract: PURPOSE:To obtain the communication control system and the switching unit to enable a loop back test while saving labor and to eliminate necessity for completely stopping communication between a communication control equipment in an operating state and a terminal equipment. CONSTITUTION:A switching unit 30 is equipped with a selecting means 14 and a loop back means 1. The selecting means 14 selects either a first or second operatable switching unit 2 or 4 and enables communication with a terminal equipment 6. While responding to a loop back test command, the loop back means 1 returns a communication data, which is transmitted from the communication control equipments 2 and 4 through the selecting means 14 for the loop back test, through the selecting means 14 to the communication control equipments 2 and 4 outputting the command. The first or second communication control equipment 2 or 4 observers the operating state of a communicating party in the state of being set standby, outputs the loop back test command to the loop back means 1 during the communication stop period of not executing communication between the party and the terminal equipment 6, and executes the loop back test.

Modem and transmission level setting method for the modem

Abstract: PURPOSE:To set a transmission level of a MODEM without a caring about characteristic of an applied communication line and without implementing a troublesome level adjustment job CONSTITUTION:When a timer 16 is operated for a prescribed time with application of power to a MODEM 1, a transmission level correction circuit 18 implements control to increase a transmission level of a transmission circuit 9 gradually during that time and a transmission signal from the transmission circuit 9 is returned to its own MODEM by a loopback function in an opposite MODEM to continue the monitoring operation of the reception level at the reception circuit 12 till the reception level is in agreement with an object value (k) Then the transmission level correction circuit 18 calculates an optimum transmission level (x) depending on, eg x=(k+y)/2 based on a transmission level (y) and the object value (k) in the case of the coincidence and sets the result to the transmission circuit 9 automatically

Atm communication system in dual ring network

Abstract: PURPOSE:To allow each node on a ring transmission line to easily restart the communication by separating an ATM cell only when information from the ring transmission line receiving an ATM cell and information by 2nd identification information are coincident and information of 1st identification information is only the information relating to a node number of a separated node. CONSTITUTION:Let a ring transmission line clockwise be a 0 system ring and a ring transmission line counter clockwise be a 1 system, then each node has a function of loopback connection of a 0 system ring output to a 1 system ring input and a 1 system ring output to a 0 system ring input so as to allow both nodes 1-3,1-4 at both ends of, e.g. a fault location 2 to activate a loopback function. On the other hand, as a VPI(virtual path identifier) as an asynchronous transfer mode(ATM) cell header information, the same 1st identification information (a) is defined in two-ways between an inserted node 1-2 and a separated node 1-4 and transmission line identification information identifying the 0 system ring and the 1 system ring is defined. Thus, the fault is coped with by allowing nodes at both ends of the fault location 2 to have only to apply loopback connection to the ring.

The link evaluation terminal for the advanced communications technology satellite experiments program

Abstract: The experimental NASA satellite, Advanced Communications Technology Satellite (ACTS), introduces new technology for high throughput 30 to 20 GHz satellite services. Contained in a single communication payload is both a regenerative TDMA system and multiple 800 MHz 'bent pipe' channels routed to spot beams by a switch matrix. While only one mode of operation is typical during any experiment, both modes can operate simultaneously with reduced capability due to sharing of the transponder. NASA-Lewis instituted a ground terminal development program in anticipation of the satellite launch to verify the performance of the switch matrix mode of operations. Specific functions are built into the ground terminal to evaluate rain fade compensation with uplink power control and to monitor satellite transponder performance with bit error rate measurements. These functions were the genesis of the ground terminal's name, Link Evaluation Terminal, often referred to as LET. Connectors are included in LET that allow independent experimenters to run unique modulation or network experiments through ACTS using only the RF transmit and receive portions of LET. Test data indicate that LET will be able to verify important parts of ACTS technology and provide independent experimenters with a useful ground terminal. Lab measurements of major subsystems integrated into LET are presented. Bit error rate is measured with LET in an internal loopback mode.

Radio transmitter-receiver

Abstract: PURPOSE:To input an AIS to a multiplex signal demultiplexer connected to a base band reception output terminal at a loopback test, to eliminate malfunction due to a line test signal and to inform the testing state to the demultiplexer by providing a selection circuit and an AIS generating circuit to the output terminal. CONSTITUTION:When a loopback test is executed, a switch circuit 1 connects a reception section and a transmission section, a selecting circuit 2 interrupts the output of a reception signal processing section 7 to connect the output of an AIS generating circuit 3. Thus, a test signal inputted from an input terminal 4 of the reception section is looped back to a transmission signal processing section 8 by the circuit 1 through a reception high frequency section 5, a demodulation section 6 and the processing section 7 and outputted from an output terminal 11 through a modulation section 9 and a transmission high frequency section 10. Moreover, an alarm signal caused in the circuit 3 passes through the circuit 2 and it outputted to a reception output terminal 12 to inform the testing state to the multiplex signal demultiplexer and to prevent malfunction by the test signal.

Radio communication equipment

Abstract: PURPOSE:To allow a time slot control section that sets a transmission signal in a transmission slot and extracts a reception signal from a reception slot to diagnose by means of the loopback method in which a specified signal is transmitted and compared with a received signal in the radio communication equipment implementing two-way communication in which a digitized transmission signal and a reception signal are allocated in different time slots. CONSTITUTION:A diagnosis control section 15 selects a switch 14 so that a output of a transmitter side time slot control section 13 is connected to an input of a receiver side time slot control section 8 only at diagnosis and controls the transmitter side time slot control section 13 so that a timing of transmission of transmission data within a specified time slot is matching a time of the reception slot. Thus, the time slot control section is diagnosed by the usual loopback method.

Optical communication equipment

Abstract: PURPOSE: To accept an instruction from an entire maintenance management equipment even in the loopback operation and to obtain the normal communication state by restoring the loopback state. CONSTITUTION: An individual maintenance management unit 5 restores a loopback changeover section 3 after lapse of a prescribed time from the reception of a loopback start instruction to release the loopback state or receives directly an electric signal from an electric signal-optical signal conversion section 2 to detect a loopback release instruction from an entire maintenance management equipment 6 to release the loopback state. COPYRIGHT: (C)1993,JPO&Japio

Loopback test control system

Abstract: PURPOSE:To facilitate specific individual channel loopback at a multiplex stage and to attain a flexible loopback test control to a medium speed by multiplexing a test instruction signal corresponding to each data signal with the same multiplex rule, as well as soon as plural data signals are multiplexed. CONSTITUTION:A multiplex section 2 multiplexes the output data signal of various terminal interface sections 1A-1N and multiplexes a test instruction signal with a same multiplex rule as that for the data signal. Thus, a multiplexed data signal resulting from time division multiplexing data signals A-C and a multiplexed test instruction signal applying time division multiplex to various test instruction signals 0, 1, 0 are obtained as the output signals of the multiplex section 2 and the multiplexed test instruction signals are fed to a selective circuit 3 as a control signal 6. On the other hand, the output signal from the multiplex section 2 is inputted to the selective circuit 3 as a loopback signal 7. Thus, a specific data signal is selected from the plural multiplexed signals with a simple circuit and looped back.

Loopback test method for atm network

Abstract: PURPOSE:To eliminate the need for the addition of a virtual channel identifier recognition function to each node by including an identifier different from a normal cell virtual pass identifier to a cell for loopback test CONSTITUTION:Lots of nodes 50-1-50-3 are interlinked to an ATM system network A fixed length cell including a VCI identifying a virtual channel set to the network and a VPI#a identifying a virtual path being a bundle of virtual channels is multiplexed and sent, and a path is switched by recognition of VPI in the cell at the nodes 50-1-50-3 In a loopback in which the loopback test is estimated for execution, the loopback use VPI#a' is allocated in advance In the case of conducting a loopback test, the loopback cell including the VPI#a' corresponding to the loopback path to be tested is sent Thus, it is not required to add a VCI recognition function to each node

Loop back control circuit

Abstract: PURPOSE:To execute a loop back test without being affected by the abnormality of a clock supplied from the outside by providing a loop back select part, loop back control part, loop back monitor part and internal clock generation part CONSTITUTION:A clock monitor part 3 monitors the abnormality of the external clock supplied from the outside for operating a loop back select part 1 and a device to be tested When any abnormality is detected, the clock supplied to the loop back select part 1 and the device to be tested is automatically switched to an internal clock generated by an internal clock generation part 2 by a loop back control part 4 Thus, without requiring any complicated operations, the loop back test can be executed without being affected by the abnormality of the clock supplied from the outside

Signal loopback system for pcm repeater

Abstract: PURPOSE:To search the fault of a relevant repeater even when the repeater at the stage behind a standardizing point generates the fault in the case of standardizing the fault point according to a test signal by setting and resetting the loopback signal of each repeater. CONSTITUTION:A tester 1 generates the first and second test signals according to positive and negative pulse trio signals a1 and a2 for setting and resetting the loopback to PCM repeating lines and transmits these test signals to the PCM repeating lines with a frequency corresponding to a filter 4 for monitoring repeaters 2 and 3. For these repeaters 2 and 3, when the number of pulses in the positive pulse trio signal detecting the first test signal by a first detection circuit 13 is a value set in advance, a first counter 15 sets the loopback of the ascending and descending PCM repeating lines. When the number of pulses in the negative pulse trio signal detecting the second test signal by a second detection circuit 16 is a value set in advance, a second counter 17 resets the return. Thus, even when the repeater in the stage behind the standardizing point generates the fault in the case of standardizing the fault according to the test signal, the relevant repeater can be searched.

Optical loopback test equipment

Abstract: PURPOSE:To conduct the loop test having an optical loopback function warranting a transmission characteristic capability with low insertion loss economically by looping back an optical transmission signal to a coupler with a loss almost equal to an optical loss between a network terminal and a line terminal when a control signal for loopback test is inputted CONSTITUTION:An optical directional coupler 9 formed in a way that an optical loss of a smaller coupling loss is slightly smaller than an optical loss between a network terminal(NT) and a line terminal(LT) and a 1X2 optical switch 10 receiving a terminal output with a larger coupling ratio of the coupler 9 are connected in cascade Then one output of the optical switch 10 connects to a line and the other output connects to the terminal with a smaller coupling ratio of the coupler and when a loopback test use control signal is inputted, the optical transmission signal is reflected to the coupler 9 while the loss of the optical transmission signal is almost equal to the optical loss between the NT and the LT Thus, the loop is tested while the transmission capability is warranted and the blocking is made clear, then a fault location and a fault time are reduced and the miniaturization and economy are attained

Transmission delay measurement device

Abstract: PURPOSE:To accurately measure a transmission delay time of a transmission line. CONSTITUTION:A request transmission means 3 of the transmission delay measurement device A sends a loopback request frame to a transmission line 10 via a transmission reception circuit 7 and a transmission time storage means 1 stores a transmission time of the loopback request frame. The transmission delay measurement device B uses an identification means 5 to receive the loopback request frame and informs it to a reply transmission means 4. The reply transmission means 4 sends a processing time required to send a loopback reply frame after the loopback request frame is received. A reception time storage means 2 of the transmission delay measurement device A stores the reception time when the loopback reply frame is received, A delay time calculation means 6 informed of the reception of the loopback reply frame obtains a round transmission delay time from the transmission time, the reception time and the processing time in the transmission delay measurement device B and calculates further a delay time in the transmission line 10.

Fault processing system

Abstract: PURPOSE:To implement fault processing quickly and automatically without modification of a transceiver in the fault processing system implementing fault processing of a device connected to a local area network (LAN). CONSTITUTION:An LAN controller 13 is provided with an LAN control LSI 15, a power supply interrupt means 17 for a transceiver 12, a 1st self-diagnostic processing means 19A self-diagnosing the LAN controller 13 based on an internal data loopback in the LAN controller 13 and a 2nd self-diagnostic processing means 19B self-diagnosing the transceiver 12 sending its own data to the LAN and receiving a data.

Duplex communication system

Abstract: PURPOSE:To supply a duplex communication system which can detect a fault in a transmission line which is usually used among duplex transmission lines on the terminal-side of an opposite-side at the time of maintenance on the duplex communication system having first and second terminals which are respectively connected to both sides of a terminal station equipment by the duplex transmission lines. CONSTITUTION:Transmission means 31 inserting codes showing first and second network ports into the prescribed positions of transmission frames and transmitting them, selection/return means 32 eliminating and returning the code which does not correspond to the network port at the time of loop back when the frame is inputted, and judgement means 33, which extract the code from the returned frame by loop back, compare it with the code showing the first and second network ports and judge whether in which network port of the opposite terminal the code is looped back are given to the first and second network ports 21 and 22 of the first and second terminals 11 and 12.

Transmission line test method and its system

Abstract: PURPOSE:To attain loopback test of each transmitter through the use of test codes of one kind of interval by sending the test codes with a prescribed detection interval of one kind to a transmission line and detecting it at each transmitter and selecting the transmission line in the transmitter corresponding to the detection interval into the loopback state. CONSTITUTION:The system consists of plural transmitters 13 provided to a transmission line comprising a forward transmission line 11 and return transmission lines 12a, 12b and a test equipment 14 as a test code transmission means. Then test codes 211, 212,... with a prescribed detection interval (t) of one kind are sent and each transmitter 13 detects the test codes 211, 212,... and the transmission line in the transmitter 13 corresponding to the detection interval (t) of the detected test codes 211, 212,... is switched into the loopback state.

Remote testing system

Abstract: PURPOSE:To test a digital line terminating device, which is spontaneously installed by a user itself, from a distant place by the user. CONSTITUTION:A second terminal equipment 21 transmits loop control information meaning the start of a loop test from a loop control information transmission and test data transmission line 22 by using a user channel. When the loop control information from the second terminal equipment 21 is detected by a loop control information detection circuit 1, a first digital line terminating device 10 operates an alarm control information transmission circuit 2 before a loop circuit 3 is operated into a loopback state, and alarm control information is transmitted to an ISDN network 30 by using an overhead channel allocated separately from the user channel. When the alarm control information meaning the start of the loop test is received by an alarm control information reception circuit 31, the ISDN network 30 controls an alarm transmission part 32 and stops the transmission of an alarm.

Control system for duplicate terminal block

Abstract: PURPOSE:To allow a terminal equipment to implement loopback to a network side normally at all times by always making the selection of a terminal equipment system match with the selection of a network side system at all times CONSTITUTION:Pattern generating means 3, 4 are provided to a terminal equipment side to insert a different pattern to an idle area with respect to lines in duplicate and pattern check means 5, 6 are provided to extract a pattern from the idle area with respect to lines in duplicate and to detect the matching with the inserted pattern Then a reception signal control means 7 is provided to control a selector 1 so that a line whose pattern match is detected is selected, and a loopback means 8 is provided to a post stage of a selector 2 of a network side to loop back the idle area Thus, the loopback toward the network side is always implemented normally by the terminal equipment side

Test control system for transmission line

Abstract: PURPOSE:To release loopback without using other code to release the loop back by providing a loopback means connecting a reception line to a transmission line for a preset time only with loopback CONSTITUTION:When a detection circuit 1 detects a loopback code from a reception line 4, a timer 2 is started A setting time is set to the timer 2 in advance The timer 2 started by the detection circuit 1 controls a changeover switch 3 by the time to select the switch 3 That is, the signal inputted from the reception line 4 is sent to the transmission line 5 via a changeover switch 3 by the control to set loopback Thus, the loopback is released without use of other code releasing the loopback state by detecting the loopback state of the transmission lines 4, 5 for a prescribed time only after the detection of the loopback code in this way