Abstract: A telephone line measurement circuit is disclosed for detecting a variation of a characteristic between a first and a second leads of a telephone line. The circuit comprises a first circuit having a first and a second inputs and an output. The circuit also has a second circuit having a first and a second inputs and an output. The first input of the first circuit and the second input of the second circuit are coupled to the first lead of the telephone line and the second input of the first circuit and the first input of the second circuit are coupled to the second lead of the telephone line. The outputs of the first and the second circuits are then coupled together to provide an output for the measurement circuit.

Abstract: A wide band noise extrapolation test system, which may reside within a processor-controlled test head installed in a central office, or as part of test signal generation and processing circuitry of a craftsperson's test set, processes data derived from applying single ended stimuli to a plurality of wirelines. The processing mechanism accurately and reliably identifies the locations and amplitudes of remote noise sources for each of the wirelines, by determining attenuation along and the lengths of the wirelines, and then modifying values of noise measurements in accordance with the determined attenuation and length values, so as to extrapolate the amplitudes of the noise at their identified source locations.

Abstract: A long-distance transmission system includes a network terminal that accommodates terminal equipment, and a line terminal connected to the network terminal via a two-wire metallic subscriber line. The network terminal includes an amplifier, which amplifies a transmission level of a transmission signal to be transmitted to the line terminal via the two-wire metallic subscriber line on the basis of a characteristic of the two-wire transmission line.

Abstract: A system and method for determining transmission characteristics for a communications channel and for transmitting data on the communications channel. In one embodiment, the method starts by determining the channel's transfer function and determining interference characteristics for the channel. The interference characteristics preferably include transfer functions describing the channel's susceptibility to cross talk from neighboring channels. The channel transfer function and the interference characteristics are then examined and a transmit spectrum (or power spectral density function) is constructed for the channel. The transmit spectrum preferably uses orthogonal separation of upstream and downstream communications to increase channel capacity.

Abstract: A line circuit for serving a digital telephone set over a link of indeterminate length and attenuation characteristics includes a processor for issuing test messages over the link to the telephone set and which responds to the receipt of an acknowledgment message from the telephone set by inserting increasing amounts of finite attenuation into the link until the acknowledgment message fails to be received, at which point the value of inserted attenuation is a measure of the excess link margin.

Abstract: A communications system is tested to simulate a realistic conversation. A first measurement device make a call, through the system it is testing, to a second measurement device and the two devices converse using predetermined speech generated dynamically by each device in response to the signals received from the other, to simulate aspects of conversation over non-perfect communications system link. The progress of the conversation will therefore take different courses according to the quality of the link. For example, if an expected signal is detected by one device, it transmits an appropriate predetermined response to the other device. However, if the expected signal is corrupted, or not received at all, different predetermined responses (or no response at all) are transmitted to the other device. This in turn may cause the other device to repeat the original signal.

Abstract: A communication line tester system and method allows for effective measurement and presentation of communication line characteristics. The communication line tester includes a transmitter, an analog-to-digital converter and a main processor. The transmitter is electrically coupled to the communication line. The analog-to-digital converter is electrically coupled to the communication line. The main processor is electrically coupled to the analog-to-digital converter. The main processor include a pseudo-random code processor configured to generate pseudo-random coded signals for transmission by the transmitter on to the communication line and to decode pseudo-random coded signals received by the main processor from the analog-to-digital converter.

Abstract: A system and method for telephone trouble reporting. One aspect of the present invention is a context-sensitive graphical user interface (GUI). The GUI allows a user to select a trouble reporting option at various stages of a telephone call in a telephony-over-LAN system. Thus, a series of menus listing potential call difficulties are provided in the interface of the digital or IP phone or telephony-enabled computer to the user during the telephone call. Selecting one of the options allows the user to report the problem to the server or other central switch.

Abstract: A system and method to detect ground faults in a multi-processor communication system that includes a communications link that extends between the processors. The processors isolate different sections of the link. Measurements made with different isolated sections establish the location of the fault. The processors can also make measurements of the link to establish the magnitude of a shunt impedance on the link. Where an abnormal value of shunt impedance is detected, the respective devices can activate or deactivate solid state isolation circuitry to disconnect a section of the link exhibiting the abnormal level of shunt impedance.

Abstract: A method and apparatus for single-ended qualification of subscriber loops for xDSL services is described. The method involves first screening a subscriber loop database record for disqualifying devices or services on the subscriber loop. If none are found, a set of predetermined electrical characteristics of the subscriber loop are derived from information in the database, or directly measured using test equipment at a central office end of the subscriber loop. The electrical characteristics are used to compute an available bandwidth on the subscriber loop for xDSL services. The advantage is the rapid and inexpensive qualification of subscriber loops which reduces response time to potential customer queries and facilitates deployment of xDSL services.

Abstract: A loop loss measurement and reporting mechanism for a digital data services unit obviates interaction with a test unit at a far end of the loop, by relying upon a priori knowledge of the signal power and spectral content of a data port at the far end of the loop to conduct threshold detection and power level measurements. A received signal is amplified by amplifier circuitry, the gain of which is controllably adjusted by the microcontroller based upon the outputs of threshold detectors and power level measurement circuitry that monitor the amplified received signal. A front panel display is controlled by the microcontroller to display loop loss parameter information. To measure and report loop loss, the digital data services unit turns off its transmitter for a prescribed period of time and monitors an in-band signal of known power and spectral content sourced from the far end of the loop.

Abstract: A method and apparatus is provided for regulating transmission power of a signal on a line. The method includes determining characteristics of the line, determining the transmission power needed to transmit the signal in response to the characteristics of the line, and transmitting the signal on the line in response to determining the transmission power.

Abstract: In a communications environment where it is desirable to allow the simultaneous transmission of digital subscriber line (DSL) signals and conventional plain old telephone service (POTS) signals on a single two-wire communication line, a method and apparatus is configured to automatically measure the distortion caused by a telephone or other attached device such as a dial modem due to the presence of a DSL signal on the same communication line, and to use such measurement to automatically and adaptively adjust the DSL output signal to achieve the highest DSL data rate commensurate with an acceptable level of distortion as required by the POTS devices.

Abstract: A line pair testing and fault diagnostic apparatus implementing three-terminal measurement techniques using a multiple frequency source waveform transmission to propagate a reflected waveform. The apparatus implements a microcomputer circuit executing a program. The program has frequency domain analysis algorithms to process the reflected waveform to provide a craftsperson with the electrical characteristic data of a line pair to inform the craftsperson the existence of a line pair fault and the location of the fault in the line pair. The apparatus implements relays for switching between several diagnostics circuits within the apparatus for providing the craftsperson with numerous methods and techniques for troubleshooting a line pair.

Abstract: A multiple tone detector includes n tone detectors, each detecting one of n distinct tones, where n.gtoreq.2, and a background detector which generates a measure of accumulative background energy E.sub.avg in a frequency band or bands which do not include at least a subset of the n tones. The output of the background detector is applied to a smoothing filter, which generates the accumulative background energy measure E.sub.avg for a current frame as a weighted sum of the background detector output for the current frame and the background energy measure E.sub.avg from a previous frame. A parameter controlling response time of the smoothing filter is varied depending upon whether or not speech is determined to be present in the background portion of the input signal. A processor uses the energy measures from the n tone detectors and the background detector to compute n ratios, where a given ratio is the ratio of the energy measure of the ith tone to the accumulative background energy measure E.sub.avg.

Abstract: A safety protection system and a related operational method for the electrical protection of users of XDSL communication circuitry. The system is based on continuous monitoring of the current parameters on both the exchange and the remote subscriber ends of the XDSL communication system. The safety protection system samples, digitizes and compares the currents at both XDSL communication system ends. The measured currents are compared to specific limiting current and currents difference levels, based on the relevant safety requirements. Whenever required, based on the measured currents status, the safety system shuts down the XDSL communication system, or limits its maximum current. In another embodiment of the invention the safety system is based on continuous monitoring of the voltages related to ground of the two system communication wires, on one or both of the exchange and the remote subscriber ends of the XDSL communication system.

Abstract: A telephone wire pair is qualified for digital signal transmission by central office testing. The tip-to-ring capacitance of the wire pair is measured while applying an test signal in the 20-30 Hz range to the wire pair. The tip-to-ring capacitance is used to compute a first length, and the first length is compared to a pre-determined length. If the first length exceeds the pre-determined length, then the wire pair is qualified based upon another comparison of the measured capacitance to a pre-determined capacitance. On the other hand, the first length is less than the pre-determined length, the tip-to-ring capacitance is measured at a frequency of, preferably, 600 Hz. The test signal at this frequency minimizes errors due to resistive and inductive components of the primary constants of the wire pair and/or a ringing device connected to the wire pair.

Abstract: A hand-held electronic instrument including a unitary, sleeve-shaped housing having a battery compartment and an electronics compartment housing a microcomputer. A sensing probe and a probe mounting member are removably mounted and fluidically sealed to the front end portion of the housing. A battery door assembly fluidically seals the rear end portion of the housing and is removable to provide access to the battery compartment for replacing spent batteries. A latch pin extending laterally from the latch operator of the battery door assembly engages a partition on the housing to retain the assembly to the housing. A battery polarizing plate disposed intermediate the battery and the electrical contacts for the battery ensure that the proper polarity is applied. Software stored in the microcomputer includes a calibration routine for facilitating calibration of the instrument and an energy savings routine for extending the life of the battery.

Abstract: An FTTH (Fiber to the HOME) or FITL (Fiber in the Loop) system comprises a FSN (Fiber Service Node) accommodating various types of subscribers and a RT (Remote Terminal) connected through an optical fiber cable to the FSN and connected through a multiplex transmission line to a central office exchange. A test unit for performing a test of the subscriber is provided within the FSN. A test start message is issued through the central office exchange to the test unit of the FSN and the test results are received through the central office exchange from the test unit of the FSN. Communication between the RT and the FSN is carried out using overhead bits of multi-frames and according to a bit-oriented process. A test command transmitted from the RT to FSN does not include subscriber types and the test unit obtains that information from subscriber circuits. Therefore, the FSN becomes compact and costs are low.

Abstract: A digital signal processor is provided with the facility to measure accurately, and nonintrusively, the levels of noise and/or speech signals appearing on an in-service network connection.

Abstract: A telephone wire pair is qualified for digital signal transmission by central office testing. The tip-to-ring capacitance of the wire pair is measured while applying to the wire pair an AC test signal at 600 Hz. The test signal at this frequency minimizes errors due to line inductance and/or a ringing device connected to the wire pair. Reliable measurement of the length of the wire pair is achieved. Flaws in cable sheathing can also be detected based on measurement of tip-to-ground capacitance and/or ring-to-ground capacitance.

Abstract: The present invention is directed to an adaptor for measuring an echo return loss in a communication system. The adaptor includes two transformers, each having a primary winding and two secondary windings. The secondary windings are cross-connected to form first and second out of phase circuits. The first circuit includes impedance elements which match an impedance of an external device. When the external device is attached to the second circuit, the first and second circuits are schematically equivalent, albeit out of phase. When an oscillation signal is input to one transformer, the matched impedance and out-of-phase connection of the secondary windings cancel the signal such that only an echo signal is output by the other transformer.

Abstract: In a telephone system wherein a number of distant terminals are each connected to a remote terminal and in which a number of remote terminals are each connected to a central office, a distant terminal includes a drop testing circuit for making sequential measurements on a plurality of customer telephones. The drop test circuit is included in a measurement system for providing condition responsive signals describing parameters of the telephone system, The drop test circuit includes circuitry such as scaling resistors, voltage sources, switching elements, and a multiplexed analog to digital voltage-sensing converter for providing digital data for transmission to the remote terminal or other more central location. The remote terminal comprises a computer based analyzer for interpreting, processing, and storing the data transmitted to it.

Abstract: Method and apparatus for detecting whether load coils are attached to a telephone line. A stimulus waveform having multiple frequency components is applied to the line. The current and voltage at the near end of the line are coherently sampled and transformed to the frequency domain. The frequency spectra are used to compute auto and cross power spectra of the current and voltage. These power spectra are then used to compute the impedance on the line as well as a coherence function that indicates the extent to which the computed impedance was influenced by noise. If the coherence values indicate that the computed impedance is sufficiently reliable, load coils are detected by finding peaks in the magnitude of the impedance function or sign changes in the phase of the impedance function. Calibration, offset adjustments and ensemble smoothing are used to increase the accuracy of the results. The computation is fast because computing the spectra avoids the need for individual measurements at multiple frequencies.

Abstract: A telephone wire pair is qualified for digital signal transmission by central office testing. The tip-to-ring capacitance of the wire pair is measured while applying to the wire pair an AC test signal at 600 Hz. The test signal at this frequency minimizes errors due to line inductance and/or a ringing device connected to the wire pair. Reliable measurement of the length of the wire pair is achieved. Flaws in cable sheathing can also be detected based on measurement of tip-to-ground capacitance and/or ring-to-ground capacitance.

Abstract: A bridge for simultaneous connection to n LANs, where n is greater than 2, and methods for determining whether the bridge has been connected properly. The bridge includes storage for respectively associating the (n.sup.2 -n)/2 unique pairs of LANs connected by the bridge with (n.sup.2 -n)/2 parallel bridge numbers. Messages received from a first LAN are forwarded to a second LAN only if the message identifies the second LAN and the parallel bridge number which is associated in the storage with the first and second LANs. To determine whether two or more ports of the bridge are connected to the same LAN, the bridge attempts to transmit messages from each of its ports to each other respective port by addressing the messages to the data link addresses of the other ports. After transmission, the bridge waits a short time interval and determines whether any of the messages are received at any of its ports.

Abstract: A measurement method and measuring circuit are described for high-speed measurement of subscriber line impedance without the influence of counter electromotive force of the bell circuit or hum noise. A measurement current is supplied from a controlled-current source to each of a pair of subscriber lines by way of switches, and subscriber line voltage and current values are measured during the transient state. A measurement time interval is divided into a first-half and a second-half interval, the average values of the voltage and current are detected for each time interval, and moreover, the difference between voltages at the beginning and end of each time interval is detected. In this case, the controlled-current source is controlled by a control means such that the rate of change of the current value over time remains at or below a fixed value.

Abstract: A method for providing an echo power measurement of a transmission line having an echo path delay wherein a frequency domain adaptive filter is converged using samples collected from the transmission line that have been converted from a time domain to a frequency domain. A regression method is used to estimate the magnitude of taps of the frequency bins of the frequency domain adaptive filter that have been determined to be not accurately converged. In addition, a method and apparatus for measuring the echo path delay of a transmission line wherein a predetermined number of first time domain adaptive filters covering predetermined time periods are converged using samples collected from the transmission line that have been subband filtered to calculate a rough estimate of the echo path delay. Then, a second time domain adaptive filter is converged using the non-filtered samples to calculate a final echo path delay.

Abstract: Apparatus and method for testing lines. The apparatus is particularly useful for testing lines in a switched network, such as might be used to electronically route telephone and computer data lines to various offices in an office building. The apparatus includes an AC test source and a DC measurement device located at a near end switch. A DC transform circuit is located at a far end switch. According to the test method, an AC test signal is injected onto a line under test at the near end. At the far end, the received signal is converted to DC, which is sent to the near end. Line attenuation, and hence fault conditions, are detected by comparing the DC signal to the transmitted AC signal. Techniques to increase the signal to noise ratio of the DC signal are also disclosed.

Abstract: An interface scanning circuit includes a current source at the input to a multiplexer. The current source includes a transistor disposed between two resistors, the second one of which limits reverse current. Also provided are an attenuating network including two resistors, and a low pass filter capacitor associated with the attenuating network.

Abstract: For measuring characteristics (resistance, capacitance, and foreign voltage) on a telephone line, source voltages are coupled via source resistances to the line in three test conditions and the parameters are calculated from steady state voltages at the terminals of the line. Each steady state voltage is predictively calculated from nine samples of the voltage at the terminal using a closed form second order solution of a circuit model of the telephone line derived from a transformation of the circuit model into the Z domain and using the matched pole-zero technique. The steady state voltages can thus be determined without waiting for transients, due to the time constants of the telephone line, to die out, resulting in much faster measurements for telephone lines with large time constants.

Abstract: Resistive faults are analyzed on a conductor in a telephone line by first charging the conductor to an initial voltage. The conductor is allowed to float for a finite amount of time, allowing some of the charge on the conductor to leak through any resistive fault. Then, the voltage of the conductor is measured and compared to the initial voltage. Loss of voltage indicates a resistive fault. This information can be used to provide an indication of the accuracy of a capacitance measurement and can be used to correct the capacitance measurement to account for the error due to the resistive fault.

Abstract: A device, for digitally measuring in real-time analog telephony signals appearing on a subscriber line during a telephone call thereover, having a converter for converting analog subscriber line voltages into corresponding digital samples, a memory for storing a number of these samples and a processor which resides in any one of various states. For each such state, the processor generates at least one different mask condition, the condition being a limit value of a pre-defined characteristic of at least a particular one of the stored digital samples relative to other such samples. The processor occupies various states with the selection of any one of these states depending upon a particular previous and/or subsequent history of the line voltages with respect to that call, i.e. the state of the call. The processor checks whether some of the stored digital samples satisfies the mask condition.

Abstract: A pulse-based cable attenuation measurement system provides a measurement of attenuation characteristics of a cable over a wide frequency spectrum. A main test and troubleshooting unit of a cable test instrument applies stimulus signals via a selected one twisted pair in a LAN cable to a pulse receiver in a remote unit that in turn causes a pulse generator to produce a specified pulse of known amplitude and duration that is applied as a measurement pulse to a separate but adjacent twisted pair within the same bundle or cable. A measurement system analyzes the measurement pulse after it reaches the main unit, and provides attenuation versus frequency information to determine whether the amount of signal loss due to attenuation in the cable is acceptable or not.

Abstract: A microprocessor-controlled voltage source selectively provides to a telephone line either a DC or an AC voltage, prescribed characteristics of which are programmably adjustable, enabling test equipment to controllably condition and test the line with essentially any desired line conditioning voltage or signal waveform. A digital-to-analog converter (DAC) provides an output voltage having an amplitude that is digitally programmable. This output voltage is available to be applied either directly or through controlled amplifier circuitry to the line. In order to generate an AC signal having both an adjustable amplitude and waveform characteristic, the output of the DAC sets the amplitude for a combination of signals from a plurality of squarewave generators having programmable frequency characteristics. The output of the combining unit is coupled to a switched capacitor filter which filters the controllably-interrupted, digitally-controllable output voltage, (e.g.

Abstract: In a quaded cable, coupling between circuits (side circuit 1, side circuit 2, and phantom circuit) is compensated for at the receiving end of a transmission system. By transmitting known signals from the transmission end separately on each circuit, coupling between circuits is initially estimated by measuring the signals received at the opposite end on each of the circuits. Following startup, during data transmission the received data signals are modified in accordance with this initially determined coupling between circuits to produce estimated transmitted data signals. During data transmission the coupling between circuits is reestimated by storing (303) N data signals received on each circuit and the corresponding N estimated transmitted data signals on each circuit. The coupling between circuits is determined as a function of the covariance of these N received signals on each circuit and the covariance of these N estimated transmitted data signals on each circuit.

Abstract: A connector unit (21) for automatically terminating a digital data services (DDS) line whenever a mating modular plug (30) is not inserted into the connector. The connector utilizes a switchable DDS jack (25) that mates with the modular plug (30) for connecting a data-transmit line and a data-receive line of a DDS network (41) to a customer's equipment (45). The connector unit has a maintenance termination circuit (40) with terminating impedances (r, r1, C and C1) and diodes (D and D1). When the plug and jack are not engaged, the maintenance termination circuit is connected to the data-transmit and data-receive lines via the normally closed jack contacts (33 and 34). As the plug and jack are engaged, the plug abuts against and, as movement continues, increasingly opens the jack contacts, causing the maintenance termination circuit to be disconnected from the customer's equipment and to be connected to the DDS network.

Abstract: The relevant data on the quality of service at different positions within a coverage area which is to be monitored of a mobile radio installation are ascertained by test mobile remote units (16) that are preferably mounted on vehicles which travel regularly on random routes (20) in the area. The test mobile remote units (16) acquire and store the call identification and connection parameters and the time and position data. Evaluation is effected via a test control unit (17), which is connected to a mobile switching center (15).

Abstract: For measuring characteristics (resistance, capacitance, and foreign voltage) on a telephone line, source voltages are coupled via source resistances to the line in three test conditions and the parameters are calculated from steady state voltages at the terminals of the line. Each steady state voltage is predictively calculated from nine samples of the voltage at the terminal using a closed form second order solution of a circuit model of the telephone line derived from a transformation of the circuit model into the Z domain and using the matched pole-zero technique. The steady state voltages can thus be determined without waiting for transients, due to the time constants of the telephone line, to die out, resulting in much faster measurements for telephone lines with large time constants.

Abstract: A method for determining the length of a telephone line from an exchange to a subscriber. The method is based on the availability in the exchange of so-called line circuits, each having a given amplification factor G for the signal transmitted from a given subscriber through the line, this factor being stored and made available to the microprocessor of the line circuit card. The attenuation for each unit of line length D between the exchange and the subscriber is known. Since these magnitudes are known, the line length L is calculated in the microprocessor from the equation L=k.G/D, where k is a constant which is calculated for a given determined length, amplification factor and attenuation/length unit.

Abstract: The rate of change of a metallic subscriber loop charging characteristic and the period of time elapsed subsequent to the coupling of testing circuitry of a remote test unit coupled to the line are measured. The operation of the testing circuitry within the remote test unit is initiated in response to the rate of change of line voltage reaching a preselected rate of change, prior to the elapsed period of time reaching a prescribed time value. If the measured period of time reaches a prescribed value prior to the monitored rate of change of line voltage reaching the preselected rate of change, the last sampled value of the line voltage is stored and reported to a mechanized loop test system supervisory site.

Abstract: An open power loop detector for digital transmission line elements using a pulsed, direct current test. The element detects when a fault in transmission lines has been corrected and the element should move from a loop powered mode back to a normal through powered mode. The detector includes a voltage regulator, voltage booster, current detector, and controller. The controller periodically activates the voltage booster to increase the direct current load between the transmit and receive cable pairs of the transmission lines. The current detector then senses whether a current is flowing between the center tap leads of the transmit cable pair. If no current is detected, indicating that the downstream transmission line still has a discontinuity, the controller waits a predetermined period of time before again activating the voltage booster and performing another test.

Abstract: For obtaining a longitudinal balance of a pair of relatively long wires, a sinusoidal stimulus signal is generated by processing digital reference signals and is applied to the pair in at least two different connection profiles. Voltages at each wire are measured in each connection profile and are combined with the digital reference signals to derive drive representative values and metallic representative values of the pair of the long wire. The longitudinal balance is calculated from these representative values. The invention requires no highly balanced circuit to provide highly accurate measurements. The measurement inaccuracies and inherent unbalance of the measuring circuitry are eliminated by the use of at least two connection profiles and signal processing.

Abstract: Method and apparatus for detecting make-break clicks on a telephone line, i.e., clicks produced by going on-hook or off-hook. A click is detected by analyzing time slices of a telephone signal to detect a sharp positive transition in signal energy followed by a diminishing envelope of short duration. Three signal measures are utilized to determine whether a click has occurred: (a) a magnitude transition, i.e., a change of the magnitude of the amplitude of the signal over a short period of time; (b) a peak magnitude, i.e., a magnitude of the amplitude of the signal corresponding to the first acceptably large magnitude transition (the beginning of the click); and (c) a duration of the signal envelope. In accordance with the present invention: (a) the minimum allowable peak magnitude of a valid click is scaled to the maximum magnitude encountered as the telephone signal is analyzed, i.e.

Abstract: In digital measurement of the amplitude and phase of a sinusoidal signal of known frequency by the least square error method, the sampling frequency and sample size are carefully selected to satisfy a certain relationship. Under these conditions, the measurements are simplified and accuracy improved. This technique of measuring a sinusoidal signal is applied to the detection of a load coil in a telephone subscriber's loop circuit. The magnitude and phase of the driving point impedance of the loop are measured through the use of a series of discrete sinusoidal stimulus signals of predetermined frequencies and a digital signal processing technique.

Abstract: A method of performing a continuity check on a speech channel in an electronic exchange system includes indicating and transmitting a continuity check request on a continuity check indicator located in a head address message if characteristics of a trunk module turn out the continuity check request while handling an outgoing call to a counterpart, and connecting a speech channel with a continuity check tone transceiver to transmit therethrough a continuity check tone; monitoring whether the continuing check tone that was transmitted through a forward channel is received back through a backward channel within a predetermined time; and if said continuity check tone is received back, terminating transmission of the speech channel from the continuity check tone, causing a timer to stop counting, and disconnecting said continuity check tone transceiver.

Abstract: An "intelligent" maintenance termination unit (MTU) that can be installed at or near the demarcation point between the telecommunications network and Customer Premises Equipment (CPE), includes a program controlled processor arranged to perform numerous testing and evaluation functions on (1) the CPE and the drop portion of the telecommunications circuit located on the customer side of the MTU, as well as (2) the line portion of the telecommunications circuit on the network side of the MTU. Testing may be initiated in response to actuation of a pushbutton switch or other initiation means by the customer. Specific tests are then performed in response to receipt of signal sequences (such as Touch-Tone signals) received from a technician at a remote test center.

Abstract: A system for determining the physical location of nodes on a network. The system includes two stations each of which has a clock. Each station uses its clock to determine the arrival times at the station of a packet transmitted over the network from a first node to a second node and of a reply packet sent by the second node to the first node. The arrival times of the packets and the corresponding reply packets are then used to calculate the distance along the network which separates the first and second node. Measurement of packet arrival times for all of the nodes yields the position of all of the nodes on the network.

Abstract: The equipment includes a front panel with LED indicators, key pad and a number of special function keys as well as an LCD message printout and volt/ohm meter. A hand set is readily available at the front panel as the line check unit functions with a commercially available craft terminal, a CMC Type 7910D terminal known as DATASTAR.TM., which includes the master central processing unit and random access memory for interactive function with the line check system. The DATASTAR.TM. unit communicates directly with a controller section that includes speaker power amp, LCD circuitry and 128K random access memory as well as a digital bus interface. The controller board is then connected through both a digital bus and an analog signal bus to an analog circuitry that includes relay control and various signal routing and test signal functions. The analog circuitry is then in communication with the volt/ohm meter and analyzer circuitry.

Abstract: A telephone system comprises a multi-channel transmission apparatus for connecting a subscriber line to a telephone exchanger, where the transmission apparatus comprises: a subscriber interface for interfacing said subscriber line; a detecting circuit in the subscriber interface for detecting a change in a voltage on the subscriber line; and a discriminating circuit for discriminating whether the change detected by the detecting circuit is continuous or intermittent, upon discriminating the detected change in voltage as intermittent the discriminating circuit outputs a first alarm signal. The discriminating circuit may be formed of a software counter which counts a number of the intermittent signals for a predetermined period. The software counter does not require a bulky and expensive components, such as a 60 Hz filter. If the counted number is larger than a predetermined number the signal is determined to be intermittent.