Abstract: Techniques for estimating distances to irregularities on a subscriber loop are described. A loop response is measured in the frequency domain. The loop response is weighted by a prolate spheroidal wave function to yield a weighted response. The weighted response is transformed to a spectral domain, and peaks in the spectral domain are identified as the distances to the irregularities.

Abstract: A method tests a subscriber line. The method includes providing a classifier to predict a performance characteristic of the line based at least in part on a value of an auxiliary variable. Each value of the auxiliary variable represents a property of the line. The method also includes performing electrical measurements on the subscriber line, using the measurements to predict a value of the auxiliary variable, and predicting the performance characteristic of the line. The act of predicting the characteristic applies the classifier to the predicted value of auxiliary variable.

Abstract: SELP techniques that provide an accurate estimate of the length of a transmission medium (e.g., subscriber loop in a DSL system) are disclosed. A probe signal is transmitted over the transmission medium at one or more frequencies. A reflected version of the probe signal is then received. Transmission medium impedance is determined based on the ratio of the reflected version of the probe signal and the transmitted probe signal. An estimate of transmission medium length is determined by comparing its impedance to a plurality of predetermined impedances, each of which is associated with a transmission medium having known length. Thus, the length of the systems transmission medium is identified. The transmission medium impedance can also be used to identify the presence of load coils and short circuits in the transmission medium.

Abstract: The invention concerns a time domain reflectometry method for estimating properties of a transmission channel, for instance a channel for transmitting electric or acoustic signals. This method includes the steps of generating, at one end of the channel, a plurality of pulses (40, 42, 44) covering differency frequency bands, and processing the echoes provided by these pulses at the same end of the channel. The frequency bands of the generated pulses are preferably overlapping. The invention is particularly applicable to the testing of ADSL services.

Abstract: The present invention synthesizes a prescribed impedance. The impedance is synthesized by generating a current having a value substantially equal to a voltage divided by a prescribed impedance. Sensing the line voltage and converting that sensed line voltage to its digital equivalent accomplish this first step. The digital line voltage is processed by a factor related to the prescribed impedance to produce an output voltage that has a value substantially equal to the sensed voltage divided by the prescribed impedance. The output voltage controls a voltage to current converter that generates the appropriate current across the points or terminals where the line voltage was measured. Thus, the prescribed impedance is generated across these points or terminals because the line voltage divided by the generated current is substantially equal to the prescribed impedance.

Abstract: A system and method of communicating between a central office and a plurality of subscriber sites. Subscriber sites are separated into frequency groups. Each group spans a distance along the cable such that no more than a predetermined amount of attenuation is required to equalize the signal power of signals sent from a site in the group. Frequency groups closer to the central office are assigned higher frequency bands than frequency groups farther away from the central office. The central office includes a plurality of filters, each of which has a passband for passing the frequency band of a group and a stop band that substantially attenuates the frequencies of the other groups. The frequency group nearest the central office has no filter. The passband of a filter may also provide any needed attenuation to assure that signals arriving at the central office have approximately the same power levels.

Abstract: The loop length, the number of bridge taps and the length of the bridged taps can be estimated by comparing through the use of differential evolution a measured frequency domain channel impulse response of the transmission line to a model of a transmission line that is composed of multiple sections and multiple bridge taps. The diagnostic and test information describing the condition of the line can then be exchanged, for example, by two transceivers during a diagnostic link mode, or the like.

Abstract: The present invention provides for an apparatus and a method for testing and evaluating a transmission line. A set of command and data signals is received through an input/output interface. The command and data signals from the input/output interface are processed for controlling at least one relay. At least one switch is activated for testing a transmission signal line using the relay. The transmission signal line is tested based upon the activated switch.

Abstract: A system for performing broadband differential time domain measurement on a subscriber loop. The system comprises a waveform generator coupled to a sampling head. The sampling head includes positive and negative pulse generators each coupled to one of the lines of the subscriber loop. The subscriber lines are in turn also coupled to two inputs of a differential amplifier, whose output is connected to an oscilloscope or other detector.

Abstract: A single ended, frequency domain reflectometry signal processing based scheme measures loop loss of a telecommunications wireline. A distortion-corrected, normalized data array is differentially combined with an associated set of wireline noise spectrum values. The resulting noise margin data is processed by a Shannon Theorem operator, to produce a set of N frequency bins, each containing the number of bits which the link will support for a respective tone. The bit contents of the bins represent a composite bit rate that is available for use for ADSL signalling.

Abstract: A line card or other telephone or communications interface provided with a ringing SLIC outputs relatively high voltage, such as in excess of about 90 volts, and/or relatively high current such as in excess of about 20 milliamps during normal use, but decreases the voltage or current of a ringing signal or other signal upon occurrence of a tip and/or ring line fault or other abnormal condition. The abnormal condition is detected by measuring voltage and/or current on the tip line and/or ring line. In response to an excess voltage or current, the ringing current or other output current is reduced to achieve desired safety and/or compliance with standards.

Abstract: A noise monitor for transmitting an actual sound (noise) when the noise level becomes higher than a regulation standard. In each noise detecting unit, the level of noise is measured through a microphone and a noise meter and input into a radio set. At the same time, an actual sound as noise is input through a microphone and a microphone amplifier into a PHS. In a noise monitoring unit, a PC communicates with the radio set in each noise detecting unit through a radio set to input the noise level measured by each noise detecting unit. The PC determines whether or not the noise level is higher than a regulation standard. If the noise level is higher than the regulation standard, the PC requests a PHS to call the PHS in the specified noise detecting unit to establish the communication between the PHS and the PHS. At this time, a maintenance worker can hear the actual sound from the PHS. Further, the actual sound is recorded by an MD recorder.

Abstract: Single Ended Line Probing (SELP) techniques for devices having transformerless hybrid circuits are disclosed. These SELP techniques provide an accurate estimate of the length of a transmission medium (e.g., subscriber loop in Digital Subscriber Line (DSL) system) by computing a transfer function that accounts for the characteristics of the transformerless hybrid circuit and the transmission medium, and relating the transfer function to the length of the transmission medium at one or more frequencies.

Abstract: A system and method for verifying the integrity of a DSL circuit on a shared telephone line. The invention uses the amplitude modulation principles to overcome the difficulty associated with a blocking capacitor that isolates a DSLAM on the DSL circuit from the rest of the shared telephone line. A transmitter of the invention mixes a high frequency carrier signal and a low frequency audio signal to produce an amplitude-modulated test signal. The amplitude modulated signal is supplied to the telephone line at a main distributing frame side of the blocking capacitor and is detected by a receiver at the DSLAM side of the blocking capacitor.

Abstract: An apparatus and a method for recreating radio frequency (RF) conditions of a cellular network extracts significant RF effects from field test data, and recreates variable RF attenuation using a multi-channel attenuator. A field data processor converts the field test data to time-varying attenuator control values for each channel of the multi-channel attenuator. Accordingly, a mobile in the lab which is connected to the multi-channel attenuator sees the same carrier and interference levels that were observed in the field environment, allowing cellular communication equipment testing without repeated field testing.

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: An equivalent working length (EWL) determinative system (11) for use in a digital subscriber line (DSL) telecommunication network (10) is provided. The EWL system (11) includes a DSL circuit (32) having a customer site (14) with customer premises equipment (30). The customer premises equipment (30) receives and transmits communication signals and generates a first attenuation signal in response to the communication signals. A remote terminal (20) forms a loop (31) with the customer site (14) and has a loop length. The remote terminal (20) includes a remote terminal transceiver (40) that is in communication with the customer premises equipment (30). A main controller (37) is electrically coupled to the customer premises equipment (30) and determines an EWL of the loop (31) in response to the first attenuation signal. A method of performing the same is also provided.

Abstract: Line states are detected accurately to efficiently test subscriber lines, thereby improving the reliability and quality of maintenance and operation. Line monitoring means monitors line states based on at least one of loop information of lines and status information of bearer channels. Subscriber line testing means conducts subscriber line testing in accordance with the line states.

Abstract: Enhanced subscriber line monitoring is provided for telephone calls in a telecommunications network. A telecommunications switch (102) is coupled to adjunct processor (104). Subscriber lines (110) terminated by the telecommunications switch are selectively monitored. Call identifying information and call content received by the telecommunications switch is forwarded to the adjunct processor for storage and analysis. The analysis includes determining the class of call content, e.g., voice or data. Call content is used to determine quality associated with a call. The call analysis is used for network management, new service development, long term usage forecasting, service differentiation for billing and targeted marketing opportunities.

Abstract: A frequency domain reflectometry-based bridged tap detection system for a telecommunication wireline employs a prescribed filtering operator, such as a ‘best-fit’ curve filter or a piecewise high pass filter bank, upstream of a Fourier processing operator, to improve the signal-to-noise ratio of the digitized amplitude array of the swept frequency band. To fit the response tones within the dynamic range of the analog-to-digital converter that digitizes the response tones detected from the wireline, a signal conditioning circuit, comprised of a comb filter bank, envelope detector and compander, is installed between the test head and the input to the analog-to-digital converter.

Abstract: A method for testing various types of devices or systems employs a modular test instrument comprising a base unit and one of a selection of application modules, neither being capable of performing end-user functions without the other. When physically assembled to one another, the base unit and application module comprise a structurally unitary device specialized for performance of application-specific end-user functions. The base unit is generic to all types of test to be provided, and comprises a display, a power supply, a user interface, and generic software to operate the display and user interface. Each application module is connected to the base unit in the same manner, so that the same base unit can be employed with a wide variety of application modules. The application modules can be readily and conveniently removed from and assembled to the base unit.

Abstract: A method for reducing audible noise in a telephone from a splitterless asymmetric digital subscriber line modem. The modem examines the shape of the power spectrum of fast retrain signals both when the telephone is on-hook and off-hook. By comparing the spectra, in particular the slopes of the spectra, the modem may determine the quality of the telephone that shares the telephone loop with the modem. The modem cuts back its transmitted power depending on the quality of the telephone by an amount that suppresses the audible noise in the telephone. In this manner, a customer may simultaneously use the telephone and the modem on the same telephone loop.

Abstract: The present invention synthesizes a prescribed impedance. The impedance is synthesized by generating a current having a value substantially equal to a voltage divided by a prescribed impedance. Sensing the line voltage and converting that sensed line voltage to its digital equivalent accomplish this first step. The digital line voltage is processed by a factor related to the prescribed impedance to produce an output voltage that has a value substantially equal to the sensed voltage divided by the prescribed impedance. The output voltage controls a voltage to current converter that generates the appropriate current across the points or terminals where the line voltage was measured. Thus, the prescribed impedance is generated across these points or terminals because the line voltage divided by the generated current is substantially equal to the prescribed impedance.

Abstract: A signal acquisition device captures signals from a telecommunication line such as a local loop. The captured signals are spectrally analyzed using a signal-processing unit. The output of the signal-processing unit—in the form of a test spectrum—is provided to a signal identification system. The signal identification system comprises at least one of a plurality of spectra of known signals stored as templates. Using a matching algorithm, the spectrum of the test signal (unknown signal) is correlated with spectra of at least two known signals. The unknown signal is determined to be the same type as that of the known signal with whose spectrum the unknown signal produces the largest absolute correlation score. Alternatively, an unknown signals is determined to be that of a known signal if a correlation of both signals results in a score the absolute value of which is greater or equal to a predetermined threshold level.

Abstract: A method tests a subscriber line. The method includes determining values of electrical line features from electrical measurements on the subscriber line and processing a portion of the values of the electrical features with a neural network. The neural network predicts whether the line qualifies to support one or more preselected data services from the portion of the values.

Abstract: Single ended line probing techniques for determining if a telephone line qualifies for digital subscriber line service are disclosed.

Abstract: A system and method of troubleshooting a communication connection for a remotely located security system is disclosed. A communication line test unit is incorporated into the remote security system and its communication unit. A central control unit can then contact the remote security system communication unit, enable the communication line test unit and perform tests on various operational parameters of the communication unit located in the remote unit and the communication connection of the local unit. The tests conducted can include loop current, tip to ring voltage, ring to ground current, circuit loss, circuit noise, power influence as well as other tests. Based on the results of these tests a determination can be made if the problem is an extraneous influence, such as a poor local telephone line connection, or some problem with the security system communication unit itself.

Abstract: A method and apparatus for selecting a supported signal path for a transceiver in a communication system is provided. An exemplary embodiment of the apparatus includes a relay for selecting a first test signal path from a first signal path and a second signal path. A signal detector coupled to the relay may be used to determine whether a specified signal type is present on the first test signal path. A relay controller causes the relay to select a second test signal path from the first signal path and the second signal path in response to the signal detector determining that the specified signal type is not present on the first test signal path.

Abstract: A system and method for transmitting data over a twisted pair with or without load coils using a transmitter and receiver is disclosed. The system detects load coils by generating and transmitting a test signal having signal power concentrated in two different frequency bands across the twisted pair and comparing the signal power of the received signal to determine whether the twisted pair is loaded or unloaded. If load coils are detected, an adjustment circuit is used to configure the receiver for reception of data over a twisted pair having load coils. Otherwise, the adjustment circuit configures the receiver for reception of data over a twisted pair without load coils.

Abstract: A method for rapid noise reduction from a splitterless ADSL modem. The modem stores a value for the power level of its transmitter in a table along with transmission characteristics of the telephone loop. The stored value for its power level is the power level that was previously successful with the transmission characteristics in achieving the Showtime data transfer mode. When the modem measures similar transmission characteristics of the telephone loop, such as a slope of the frequency response of the loop, a power level that would suppress downstream noise, or the dc voltage of the loop, the modem searches the table for matching transmission characteristics. If the table contains a table entry that matches these measured transmission to characteristics, the modem restores the stored transmitter power of the modem. In this manner, the modem may rapidly achieve Showtime because it is restoring a transmitter power level that was previously successful under the same condition of the telephone loop.

Abstract: Circuits for testing POTS service on a shared POTS/xDSL carrier include microfilters for selective coupling to the subscriber loop side of an xDSL filter associated with a subscriber line interface circuit. Such configurations facilitate testing of the POTS service using an insertion point that is between the xDSL filter and the subscriber loop in a manner that is transparent to subscribers.

Abstract: A portable, automated telephone line test device includes a test module which applies test signals to a telephone line to be tested and detects electrical characteristics of the telephone line, and a user interface module. The user interface module includes a microprocessor, a display, a keyboard and a program memory in accordance with a standard microcomputer architecture. The processor of the user interface module is programmed to control the test module to perform a pre-programmed sequence of tests. The display provides indications of the tests being performed. The programmed sequence is varied by the device according to test results. Depending on the results obtained, the device also provides interpretative diagnostic messages and instructs the user to carry out additional test procedures.

Abstract: Method for measuring a load impedance (ZL) of a load circuit which is connected to an SLIC circuit (6) of an analog terminal connection of a terminal device, having the following steps: specifically a digital toll signal (x1) is generated by means of a Codec circuit (13) connected to the SLIC circuit (6), said toll signal (x1) being converted into an analog toll signal; the analog toll signal is output by the SLIC circuit (6) to the load circuit; an analog voltage which is brought about at the terminal connection (4,5) of the terminal device of the SLIC circuit (6) via the analog toll signal is sensed; the digital toll signal (x1) is filtered by means of an adaptive filter (39) which is provided in the Codec circuit (13) and has adjustable filter coefficients (g1, g2) for generating a filtered digital comparison signal (yv) which is converted into an analog comparison voltage (Uv); the filter coefficients (g1, g2) of the adaptive filter (39) are adjusted until the analog comparison voltage (Uv) and the analog

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 for testing telephone equipment for longitudinal balance. A signal generating circuit places a test signal at a certain frequency on the tip and ring wires of a telephone line. The telephone line is monitored and the signals on the tip and ring wires are measured and compared against each other. The frequency is gradually increased in set increments until the test frequency is in the megahertz range.

Abstract: The method is for controlling the transmission power for a session in a system when transmitting data via a telephone line by using a digital subscriber line between a user terminal and a central unit. The transmission power is increased or decreased between given limit values so that the transmission power is kept as low as possible while still providing a sufficient transmission quality. The transmission quality, and therefore the transmission power, is controlled by the value of the signal-to-noise ratio and the number of bit errors BER within a given time interval.

Abstract: The invention relates to a method for measuring the quality of a network (10) for the transmission of digital or analog signals, including the connections (16,18) associated with said network (10) which are used to connect telecommunication terminals such as telephones (22), fax machines (26), modems (24), mobile telephones (20) or the like to the network (10), by means of an INMD measuring method.

Abstract: A method for controlling transmission power from a customer premise equipment device over a local loop of a digital subscriber line involves determinating a maximum power level for transmissions over the local loop. The maximum power level is based on a response of the local loop to a test signal to allow a different loop in the binder group to have a different maximum power level to reduce potential for crosstalk in the binder group.

Abstract: The invention provides a system and method for testing a telephone or communications line to determine if the line qualifies for a particular type or class of communications service, for example DSL service. In accordance with one embodiment, a potential customer can download a software program. The program first performs a DSL distance qualification calculation. If the customer's line passes this step, the program determines whether the line coupled between the customer and a central office servicing that customer is electrically qualified for DSL communications. A series of tests to measure signal levels, noise, and other characteristics are performed by a test server, which generally include local loop tests to determine the presence of bridged taps, load coils, and subscriber line concentrators. After the tests are completed, the customer can receive the results, order completion and other instructions.

Abstract: A method tests a subscriber line. The method includes providing a classifier to predict a performance characteristic of the line based at least in part on a value of an auxiliary variable. Each value of the auxiliary variable represents a property of the line. The method also includes performing electrical measurements on the subscriber line, using the measurements to predict a value of the auxiliary variable, and predicting the performance characteristic of the line. The act of predicting the characteristic applies the classifier to the predicted value of auxiliary variable.

Abstract: A test system automatically locates impedance mismatched, energy reflection discontinuities (e.g., bridged taps) along a wireline communication link, by coupling a linearly stepped sinusoidal waveform to a measurement location of the wireline link. The applied waveform propagates down the link and is reflected back from the energy reflection discontinuities. A line monitoring receiver coupled to the measurement location samples the response of the line to the swept waveform. A response processor executes a frequency domain reflectometry algorithm to analyze the frequency response of the wireline to the stepped frequency waveform. It then generates an output representative of distances from the measurement location to the bridged taps.

Abstract: An improved digital signal line carrier type detector non-conductively senses and counts voltage pulses on a probed line. Further, the detector produces a human-readable display of the carrier type in use on the probed line, and can detect carriers of various frequencies without the use of multiple oscillators or probes. The detector may be housed in a hand-held portable housing, and may be powered by one or more batteries. A timer circuit is usable with the detector to prevent accidental discharge of the battery for an extended period of time.

Abstract: An air interface simulator and simulation method is disclosed.

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: An apparatus and a method a method for testing, configuring, and evaluating a transmission line. The method receives a set of command and data signals through an input/output interface and processes the command and data signals from the input/output interface for controlling at least one relay. The method also activates at least one switch for testing and improving a transmission signal line using the relay and testing and emulating the transmission signal line based upon the activated switch. The method also configures the transmission signal line based upon the testing and emulating.

Abstract: A test stimulus includes two signals RR, S. Signal S is transmitted to a customer equipment interface and over a system under test to a complementary remote apparatus. The test apparatus has two inputs processed by a number of functional elements. The first input is the reference signal RR. The other input is a corresponding test signal R′ generated at remote test apparatus as a test signal R, identical with reference signal RR, and transmitted over the system under test via the customer interface. These two versions of the same test signal are compared. Firstly, the signals RR, R′ are processed by a psycho-acoustic model, the output of which is transmitted to a perceptual layer, and then to a conversion unit which also receives a further input from a non-optimum loudness rating unit. The output from the conversion unit is transmitted to a signal quality determination unit, which also receives an input from the customer equipment interface.

Abstract: A method detects a fault in a subscriber line having two wires with separate input impedances. The method includes driving the subscriber line from one end with an alternating voltage, making one-ended electrical measurements on the driven liner and determining from the measurements a quantity proportional to the phase difference of the two input impedances. The method also includes identifying a fault in response to the phase difference having a signature associated with presence of a fault in the line.

Abstract: A method and automatic test system for determining qualification of a twisted pair transmission line to propagate data signals. The method includes measuring phase imbalance in the twisted pair transmission line. The phase imbalance is determined by resistance imbalance in the twisted pair transmission line. The resistance imbalance is determined by applying a common mode voltage to the twisted pair transmission line; and, determining phase imbalance in the twisted pair in response to the applied common mode voltage. The method includes applying a common mode voltage to the twisted pair transmission line; determining phase imbalance if the twisted pair in response to the applied common mode voltage; detecting a peak in the determined phase imbalance; determining a frequency of the detected peak; determining line qualification in accordance with the determined frequency.

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 is provided for communicating on an equipment network. According to the method, a message is sent from a sending equipment unit to a receiving equipment unit as a signal having a nominal power. Whenever the signal is amplified by an intermediate equipment unit through which the signal passes, the message is modified to indicate that the signal has been amplified by the intermediate equipment unit. Also provided is a first equipment unit for connection to an equipment network.