Abstract: A delay-line time-domain reflectometer includes a return detector configured to process a discharge pulse produced by discharge of a line capacitor, formed by the physical relationship of a pair of conductive wires forming a telephone line, from a predetermined DC voltage. The return detector includes a number of neural networks configured to process the discharge pulse under the control of a controller. The neural networks enable the controller to characterize the loop configuration of the telephone line, where the loop configuration includes the length of the telephone line, the position of any bridged tap connected to the telephone line and/or the length of any bridged tap connected to the telephone line.

Abstract: An apparatus for testing a telephone line (12) includes a charge generator (4) for selectively charging a line capacitor (16) formed by the physical relation of at least two electrically conductive leads (8, 10) of the telephone line (12) to a predetermined DC voltage. A line clamp (6) selectively connects the leads (8, 10) together and a return detector (18) receives a discharge pulse (22) produced by discharge of the line capacitor (16) in response to the line clamp (6) connecting the leads (8, 10) together. The return detector (18) detects an end-of-line pulse (28) and/or a bridged-tap pulse (32) superimposed on the discharge pulse (22) and outputs an analog return signal as a function thereof.

Abstract: A telephony test system (34) has a communication interface (52, 54, 56) connected to communicate with a remote terminal (16). In response to receiving an electrical test request signal from the remote terminal (16), a controller (50) causes an analog-to-digital converter (DAC) (70) to produce an analog signal which is supplied to a high voltage amplifier (124) which amplifies and supplies the amplified analog signal to customer telephony equipment (6). Controller (50) measures the response of customer telephony equipment (6) to the amplified analog signal and determines from the response and the amplified analog signal an electrical power dissipated by the high voltage amplifier during supply of the amplified analog signal. Controller (50) controls a power supply to adjust the voltage supplied to the high voltage amplifier (124) to avoid electrical power dissipated thereby during supply of the amplified analog signal from exceeding a desired maximum electrical power dissipation.

Abstract: An electronic relay matrix (22) is connectable between a plurality of customer telephone lines and a plurality of testers (2, 201-203). The electronic relay matrix (22) includes a line matrix (80) having a plurality of relay assemblies (821-8250). Each relay assembly (82) in a relaxed state connects together the line-side (12) and the drop-side (8) of one of the customer telephone lines. Each relay assembly (82) is adjustable to enable one of the plurality of testers (2, 201-203) to be connected to the drop-side (8) and/or the line-side (12) of a desired customer telephone line.

Abstract: An electronic relay matrix (22) is connectable between a plurality of customer telephone lines and a plurality of testers (2, 201-203). The electronic relay matrix (22) includes a line matrix (80) having a plurality of relay assemblies (821-8250). Each relay assembly (82) in a relaxed state connects together the line-side (12) and the drop-side (8) of one of the customer telephone lines. Each relay assembly (82) is adjustable to enable one of the plurality of testers (2, 201-203) to be connected to the drop-side (8) and/or the line-side (12) of a desired customer telephone line.

Abstract: One or more pieces of equipment of a hybrid fiber-coaxial (HFC) network has a frequency agile transponder connected thereto. Each frequency agile transponder includes a transmitter (T) and a receiver (R) which are connectable to a coaxial line of the HFC network. Bidirectional communications can occur between a controller and each frequency agile transponder via the HFC network. The frequency agile transponder has analog inputs/outputs connectable to test points of the one or more pieces of equipment of the HFC network. The frequency agile transponder can test the test points and supply to the controller the results of the test. The transmit and receive center frequencies of the transmitter and receiver of the frequency agile transponder can be selectively and remotely adjusted by the controller to avoid signals at carrier frequencies utilized to transmit program material, data signals and/or telephony signals.

Abstract: A remote telephone testing device (22) includes a transmitter (30), a receiver (24), a controller (26) and a test circuit (28). In response to the receiver (24) receiving a test signal from a test system (20) via a telephone network (2, 4, 6, 8), the controller (26) communicatively isolates telephone equipment (10) of a subscriber (S) from the telephone network (2, 4, 6, 8) and connects the test circuit (28) to the telephone equipment (10). The test circuit (28) tests the telephone equipment (10) and conveys one or more results of such test to the controller (26) which relays the one or more results to the test system (20) via the transmitter (30). When testing is complete, the telephone equipment (10) is isolated from the test circuit (28) and is communicatively connected to the telephone network (2, 4, 6, 8).

Abstract: A telephone test system (2) includes a controller (4), a programmable gate array (PGA) (24) and a digital signal processor (DSP) (26) connected by a common bus (20). The PGA (24) includes an output connected to an input of a digital-to-analog converter (DAC) (36) and input connected to an output of an analog-to-digital converter (ADC) (32). A driver circuit (46) is connected between the DAC (36) and a telephone circuit (60) and between the ADC (32) and the telephone circuit (60). Under the control of the DSP (26), the driver circuit (46) generates voltages to the telephone circuit (60) and samples the response of the telephone circuit (60) to such generated voltages. The driver circuit (46) includes control inputs for receiving from the PGA (24) an impedance adjust signal (D) and a resistance adjust signal (R). An output impedance (124) of the driver circuit (46) connected to the telephone circuit (60) is adjustable as a function of the impedance adjust signal (D) and/or the resistance adjust signal (R).

Abstract: A broadband network for providing broadband signals, such as cable television signals, to a subscriber location includes a network interface device installed at the subscriber's end of the broadband network. The network interface device includes circuitry that provides for the selective provisioning of services to the subscriber location from the broadband network and a test circuit that can be selectively connected for testing signals appearing on the broadband network.

Abstract: A channel unit network having a two-wire port for interconnecting a two-wire, bidirectional signal transmitting means with a four-wire digital transmitting means in a communication system to create a precision bidirectional simulated two-wire cable pair with an extended operation range over a transmission medium includes a signal processing circuit, tip and ring switch mode driver, a negative inductor circuit, a negative capacitor circuit, and a 200 Hz impedance circuit. The negative conductor circuit and the negative capacitor circuit are used to generate respective negative inductance and negative capacitance at 24 Hz in order to maintain loop stability. The 200 Hz impedance circuit is used to generate a positive impedance at a frequency of approximately 200 Hz so as to prevent overloading of external telephone communication testing circuitry.

Abstract: A channel unit network for interconnecting a two-wire, bidirectional signal transmitting means with a four-wire digital transmitting means in a communication system to create a precision bidirectional simulated two-wire cable pair over a transmission medium includes tip and ring switch mode drivers, a signal processing circuit, a decoupling circuit, and tip and ring balance amplifiers. The decoupling circuit is used for splitting off "voice band" frequency signals from incoming tip and ring "DC band" signals from the two-wire means. The signal processing circuit performs both analog-to-digital conversions and digital-to-analog conversions.

Abstract: A metallic channel unit network for interconnecting a two-wire, bidirectional signal transmitting means and a four-wire signal transmitting means in a communication system includes a voice hybrid driver, A/D signal processing circuit, D/A signal processing circuit, tip and ring switching drivers, and tip and ring sensing amplifiers. The metallic channel unit network is suitable for use with substantially all of the different alarm-signalling techniques utilized by the various alarm companies for connecting their equipment to a channel bank multiplexer coupled to the four-wire means. The metallic channel unit network provides an apparent metallic cable pair over the digital carrier in the frequency range of DC to 3.5 KHz with an amplitude variation between +200 to -200 VDC.

Abstract: An enhanced amplifier for interconnecting a two-wire, bidirectional cable side transmission path and a two-wire bidirectional equipment side transmission path in a communication system includes a first hybrid splitter and a second hybrid splitter. The first hybrid splitter is formed of a cable-to-equipment voltage sense amplifier, a shunt current driver, and a series current compensator for generating a first simulated terminating impedance. The second splitter is formed of an equipment-to-cable voltage sense amplifier, the shunt current driver and the series current compensator for generating a second simulated terminating impedance. Other features disclosed include automatic gain adjustment circuitry for automatically setting the gain in gain/equalizer circuits to a fixed level. Further, auto-balancing circuitry is provided for adjusting automatically and continuously both equipment and cable side balance networks.