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 method and apparatus are provided for determining transmission line parameters of a length of single-wire transmission line that is deployed in seawater. The seawater is utilized as an electrically grounded return for the transmission line such that a two-port network is formed at either end of the transmission line. An alternating voltage of known amplitude and frequency is generated and applied to a first end of the length of transmission line. Open and short circuit parameters at the first end are then determined as a second end of the length of transmission line is alternately switched between a open and short circuit mode. The alternating voltage of known amplitude and frequency is then applied to the second end as the first end is alternately switched between an open and short circuit mode so that open and short circuit parameters may be similarly determined at the second end.

Abstract: A method of testing a telephone line including installing a test call unit at an end of the telephone line at which a customer's equipment is connected, automatically initiating a telephone line test at the module, performing the telephone line test, and transmitting the results of the line test over the telephone line.

Abstract: An arrangement of digital circuitry is disclosed for testing a cable communication system to determine its performance when subjected to near-end cable crosstalk. The circuitry digitally generates a crosstalk signal indicative of the combined effect of one or more interfering sources and the near-end crosstalk coupling path linking the interfering sources with the system-under-test. The circuitry includes a pseudo-noise sequence generator for producing a stream of bits that are normally distributed and a digital filter, responsive to the sequence generator, for implementing a frequency characteristic corresponding to the spectral content of the interfering source as weighted by the near-end crosstalk path.

Abstract: Apparatus is described for testing a telephone line between a customer's telephone and a local exchange associated therewith. The apparatus comprises a field unit positioned between the customer's telephone and the line, an exchange unit positioned at the exchange, and a microcomputer associated with the field unit for controlling operation of the field unit and the exchange unit. The field unit and the exchange unit each have means for transmitting frequency tones down the line and means for measuring the voltage across the line. The microcomputer is programmed to calculate the loudness rating of the line from the measured voltage values.

Abstract: A simple impedance measuring tool is provided for performing an accurate but inexpensive determination of impedance and assurance of an impedance match in an installation environment. The apparatus operates according to a method wherein the average instantaneous voltage on a transmission line is sensed based on the integration of a series of reflections stimulated by a pulse generator. The apparatus comprises a fast repetitive pulse generator, a fast comparator, a flip-flop and a means for integrating the output of the flip-flop to produce an output voltage which can be read by a simple low-cost meter such as a d.c. voltmeter. The output of the comparator is coupled to the data input of the flip-flop, which is driven at its clock input by a variable phase clock output of the pulse generator. The absolute time delay or phase determines the distance at which the measurement is to be taken.

Abstract: The central unit (14) comprises a distortion sampler (16) including a spectral sound analyzer and a memory for recording the digital data of at least one reference sound. The central unit by means of the analyzer analyzes a sequence of such sounds which are received by way of the telephone line (11, 13) and makes a comparison with the recorded data. It thus produces a measurement of the frequency response of the transmission, that is to say distortion and attenuation introduced by the telephone connection, in accordance with the various frequencies. The data of that measurement are used by the central unit (14) to compensate for the signals which are successively received by way of the activated telephone connection. The system comprises a portable acoustic device (35) in which the digital data of the reference sound are recorded.

Abstract: Methods and apparatus for measuring propagation delay over a line without interfering with data communications over the line are disclosed. A known signal is sent and looped back over a secondary channel, and the loop time is measured. Because the known signal is sent at a non-interfering frequency at the edge of the passband, the loop time minus fixed delay times of the communicating means does not provide a true measure of propagation delay. Rather, the envelope delay distortion must be determined and also subtracted from the loop time. The envelope delay distortion is determined as a function of the utilized non-interfering frequency and the line length, the latter of which may be estimated from the loop time.

Abstract: A voltage measuring device for accurately sensing the AC load voltage at remote, distal end of a long, two-conductor cable, the measuring device comprising a parallel arrangement of an AC source and a DC voltmeter, located at the proximal, source end of the cable, and an AC load in parallel with a passive, DC producing module at the distal, load end of the cable, the passive module further comprising a passive, DC producing voltage divider, the output of which is proportional to the AC load voltage drop.

Abstract: This automatic telephone line fault locator comprises a portable box-type structure which comprises an interface section including switches and having input terminals for connection to a line being controlled, a voltage and current measuring section electrically connected to the interface section for selectively measuring currents and voltages of suitable portions of the line being controlled, a control unit including a logic-arithmetic and control section coupled to the interface section and the measuring section for controlling the position of the switches and receiving the measured current and voltage values and calculating therefrom the position of any fault on the line.

Abstract: A circuit for detecting a first plurality of status signals on a multiplicity of telephone lines and generating a second lesser plurality of control signals, less than the first plurality, in response thereto. Predetermined ones of the control signals are transmitted via a multiplexing circuit to a comparator circuit. A digital-to-analog converter generates analog threshold voltages for application to the comparator circuit in response to receiving command signals from a microprocessor. The comparator circuit generates a third lesser plurality of output signals, less than the second plurality, indicative of the status of a multiplicity of remote trunk circuits connected to the telephone lines. The circuit is inexpensive and occupies little circuit board area.

Abstract: There is disclosed a circuit for monitoring a capacity of a subscriber line to which a capacitor equivalently representative of a telephone set is connected. This monitoring circuit has a test sequence for the subscriber line capacity. The test sequence comprises a first step to connect the subscriber line to a test circuit, and second step to apply a backward voltage to the subscriber line, thereby to discharge an electric charge stored in the equivalent capacitor. The test sequence further comprises a third step to apply a forward voltage to the subscriber line through a reference capacitor, thereby to charge the equivalent capacitor to evaluate the capacity value of the equivalent capacitor on the basis of a voltage appearing across the equivalent capacitor, thus to effect a capacitive test of the subscriber line.

Abstract: Analog voltages are collected by scanning the two wires of a subscriber line; the values are subjected to an analog-digital conversion and fed to a microprocessor (MC) which computes the desired measuring values from the results of said conversion. Thus, from a single measuring operation performed at two measuring points, nine different voltage values can thus be obtained including dc, ac and external voltages between each wire and ground and between the two wires.

Abstract: A method and apparatus are described for testing a telecommunication line despite a gap in a metallic line between the testing system at a central office and the subscriber's line. On the subscriber's or remote end of the gap in the metallic line, apparatus is provided for performing certain desired tests on the continuous metallic portion of the subscriber's line. This apparatus is connected to a testing system on the central office or local side of the gap with suitable communication equipment so that tests performed on the remote end may be reported back to the testing system. The remote end testing apparatus is similar to apparatus described in application Ser. No. 645,479. The testing system at the central office preferably is a conventional system, such as the MLT system which already is installed in many central offices throughout the United States, together with the necessary modifications to communicate with and control the remote end testing apparatus.

Abstract: A test trunk access controller includes a test trunk interface controller accessed by a subscriber line assigned to a service provider, or other remote metering facility, and a test trunk interface device inter-connecting the test trunk controller with the test trunk device of a local telephone switch.

Abstract: The present invention discloses a device for detecting the presence of an intruder listening device on a telephone or data line. The device comprises an electrical circuit electrically connected to the telephone line for measuring the values, polarity and electrical characteristics of the telephone line. These measured values are then compared with predetermined values for each electrical characteristic which are stored by the electrical circuit. An indicator is activated by the electrical circuit when the measured value varies from its respective predetermined value by more than a predetermined amount. The circuit, which is preferably microprocessor controlled, also includes a signal sweep generator for generating one or more electrical wave forms into the telephone line as well as a receiver which receives and analyzes the reflected signal from the telephone line.

Abstract: A method of detecting hazardous line voltages over a two-wire line for transferring digital information. At one end, the line is terminated by a hybrid coupler (G) and an apparatus for adaptive echo elimination. This apparatus generates a digital signal (d) constituting an unambiguous measure of the difference between the line impedance (Z.sub.L) and the hybrid impedance (Z). This signal is compared with two digital limiting values (d.sub.1,d.sub.2) an alarm being given should either these two values be reached or exceeded.