Abstract: The test instrument is used to perform both time domain reflectometry (TDR) and analysis of transmission signals on a line under test. Further, the test instrument provides for both pulse TDR and step TDR. A coupling transformer having an enhanced low frequency response provides for coupling of the test instrument to the line under test. Isolation circuits between the coupling transformer and the line under test to prevent damage to the test instrument due to voltages on the line under test allow the test instrument to be used in connection with an active line under test. Two isolation circuits are utilized to maintain longitudinal balance of the circuit. During step TDR, the positive and negative transmitter circuits provide step-shaped impulse signals.

Abstract: A bridge module provides connection between first and second conductors of a line under test and a test instrument adapted for use with the bridge module. The bridge module provides monitoring and measurement of DSL communication signals between the telephone company DSL terminal (DSLAM) and the subscriber home DSL equipment across a wide range of frequencies. The bridge module can be used at any point in the communications link and can be used while the link is active. The bridge module provides a clickless connection to the active DSL communications link to avoid interruption in DSL service.

Abstract: A device for measuring and isolating noise-creating imbalances in a paired telecommunications line has an internal circuit. The internal circuit includes a pulse generator. Pulses provided by the pulse generator are applied to an interface which includes balanced pathways to the conductors. The pulses are applied simplex (longitudinally) to the pair of conductors. Upon encountering a fault in the pair, a reflected metallic voltage signal is received by the interface. The reflected metallic voltage signal is sampled by an analog-to-digital converter. Data relating to the sampled signal is displayed for detection and location of faults on the pair.

Abstract: The test instrument is used to perform both time domain reflectometry (TDR) and analysis of transmission signals on a line under test. Further, the test instrument provides for both pulse TDR and step TDR. A coupling transformer having an enhanced low frequency response provides for coupling of the test instrument to the line under test. Isolation circuits between the coupling transformer and the line under test to prevent damage to the test instrument due to voltages on the line under test allow the test instrument to be used in connection with an active line under test. Two isolation circuits are utilized to maintain longitudinal balance of the circuit. During step TDR, the positive and negative transmitter circuits provide step-shaped impulse signals.

Abstract: A bridge module provides connection between first and second conductors of a line under test and a test instrument adapted for use with the bridge module. The bridge module provides monitoring and measurement of DSL communication signals between the telephone company DSL terminal (DSLAM) and the subscriber home DSL equipment across a wide range of frequencies. The bridge module can be used at any point in the communications link and can be used while the link is active. The bridge module provides a clickless connection to the active DSL communications link to avoid interruption in DSL service.

Abstract: A device for measuring and isolating noise-creating imbalances in a paired telecommunications line has an internal circuit. The internal circuit includes a pulse generator. Pulses provided by the pulse generator are applied to an interface which includes balanced pathways to the conductors. The pulses are applied simplex (longitudinally) to the pair of conductors. Upon encountering a fault in the pair, a reflected metallic voltage signal is received by the interface. The reflected metallic voltage signal is sampled by an analog-to-digital converter. Data relating to the sampled signal is displayed for detection and location of faults on the pair.

Abstract: A pulse generator includes circuitry for starting a pulse in response to receipt of a pulse enable signal. The pulse enable signal is synchronous with a first time base. The pulse generator includes circuitry for ending the pulse after a predetermined, user selectable, number of clock cycles. The clock cycles have a second time base that is asynchronous with the first time base. Since the end pulse signal is not on the same time base as the pulse enable signal, there is up to one asynchronous clock cycle period random variation in width of pulses having the same nominal width.

Abstract: A time domain reflectometer transmission line interface includes a pulse driver for generating a transmitted pulse signal. A coupling transformer coupled to the pulse driver couples the transmitted pulse signal to a transmission line and receives a reflected pulse signal from the transmission line. A differential amplifier is coupled to the pulse driver and to the coupling transformer through a network configured such that said transmitted pulse is balanced at the inverting and non-inverting inputs of the differential amplifier.

Abstract: A pulse generator includes circuitry for starting a pulse in response to receipt of a pulse enable signal. The pulse enable signal is synchronous with a first time base. The pulse generator includes circuitry for ending the pulse after a predetermined, user selectable, number of clock cycles. The clock cycles have a second time base that is asynchronous with the first time base. Since the end pulse signal is not on the same time base as the pulse enable signal, there is up to one asynchronous clock cycle period random variation in width of pulses having the same nominal width.

Abstract: A system and method of data acquisition for transmission line performance evaluation and fault detection applications may incorporate wideband topology from reception of signals to be analyzed through to a high speed analog to digital converter. In accordance with one aspect of the present invention, for example, wideband variable gain amplifier and attenuation circuitry may be employed in conjunction with high speed sampling circuitry to facilitate event detection in a transmission line or wire; this implementation additionally allows seamless integration of spectrum analysis functionality in a single data acquisition system.

Abstract: A time domain reflectometer transmission line interface includes a pulse driver for generating a transmitted pulse signal. A coupling transformer coupled to the pulse driver couples the transmitted pulse signal to a transmission line and receives a reflected pulse signal from the transmission line. A differential amplifier is coupled to the pulse driver and to the coupling transformer through a network configured such that said transmitted pulse is balanced at the inverting and non-inverting inputs of the differential amplifier.

Abstract: A D channel monitor is provided which is capable of providing a plurality of operating modes for monitoring D channel operation. As such, the D channel monitor can include first and second interface elements which can be operated to appear as either an NT interface (for a TE) or as a TE interface (for an NT). A controller is provided which can control the first and second interface elements to appear as predetermined ones of the NT interface or the TE interface for respectively coupling to either a TE or an NT of the ISDN user terminal. A monitoring arrangement is also included for monitoring the D channel signals at the terminal which are received through either of the first and second interface elements. This monitoring arrangement includes means for indicating the status of the D channel signals to a user.

Abstract: An integrated services digital network (ISDN) traffic generator adapter is provided for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch. In particular, first circuits provide a plurality of two-way communication links between the analog traffic generator and the ISDN switch. Each of said first circuits includes elements for converting the analog telephone signals from the analog traffic generator into a plurality of ISDN signals, including B channel information and D channel information, for said ISDN switch, and elements for converting a plurality of ISDN signals from the ISDN switch, including B channel information and D channel information, into analog telephone signal for said analog traffic generator. A processor is coupled to the plurality of first circuits for selectively addressing individual ones of said plurality of first circuits.

Abstract: The telephone line test capability of a craftsperson's test set is supplemented by communication/interface circuitry which carries out data communications with a host central office control processor, and contains memory for storing (task assignment) information downloaded from the central office control processor. This task assignment information stored in the test set-communications unit may be coupled from the unit to an associated printer for providing a hard copy of service assignment information to the field technician. In addition to printing out the downloaded task assignment information, the printer unit contains a charging circuit which charges a rechargeable battery in the handset for powering its internal circuitry. During off-duty hours, the test set may be connected to a home dispatch unit installed in the craftsperson's home and through which the handset is coupled to a telephone link for providing off-duty communications with the central office processor without technician intervention.

Abstract: An improved telephone test unit is disclosed which permits the telephone line technician to selectively choose the audio reproduction of signals ocurring on the line without the use of the handset in the test unit. An auxiliary amplifier is provided to amplify the signals which are received from the telphone line. When the amplifier is activated, the transmitting unit and receiving unit of the handset within the telephone test unit are electronically muted to prevent undesirable audio feedback to the amplifier. The gain of the amplifier may be selectively varied between an off, low and a high gain condition. The amplifier is also usable in the "monitor" condition of the telephone test unit.

Abstract: An improved telephone test set is disclosed which may be operated with low voltage line conditions. Transmitting and receiving voice communication circuits are connected in parallel with leads which are adapted to be connected to the tip and ring lines of a subscriber's telephone line to isolate the voice transmitting and receiving circuits from the voltage drop of a polarity guarding bridge which is connected to the signalling circuits of the telephone test set. A polarity indicating circuit to indicate the direction of current flow between the tip and ring lines of a subscriber's telephone line is connected in series with the voice transmitting and receiving circuits.