Abstract: A methodology for identifying a telephone receiver-off-hook (ROH) condition within the class of resistive faults occurring on a subscriber line is disclosed. The method utilizes the nonlinear DC characteristic exhibited by an off-hook handset. First and second DC resistances are measured in response to first and second DC sources applied at a test point associated with the line. A resistance differential between the two resistances is compared to a resistance range. A ROH condition is indicated if the differential falls within the range.

Abstract: A mechanized system distributing the access, test and communication functions to the point of testing, typically the centralized switching facility serving the telephone loops and equipment to be tested. Computer (200) stores information about each subscriber loop in the geographical area served by a system. Front-end computers (220,221) interact with computer (200) to retrieve pertinent data regarding loops to be tested. Each switching facility in an area includes a loop testing system (e.g., 160) that implements the required functions. The communication functions residing in front-end computers (220,221) and loop testing systems (160,161) are coupled via a data communication network (140) in a manner that allows any front-end computer to communicate with any loop testing system. Users of the system control access and test from consoles having the capability of establishing independent communication paths over the national dial network for interactive tests on loops accessed through standard test trunks.

Abstract: A mechanized system distributing the access, test and communication functions to the point of testing, typically the centralized switching facility serving the telephone loops and equipment to be tested. Computer (200) stores information about each subscriber loop in the geographical area served by a system. Front-end computers (220,221) interact with computer (200) to retrieve pertinent data regarding loops to be tested. Each switching facility in an area includes a loop testing system (e.g. 160) that implements the required functions. The communication functions residing in front-end computers (220,221) and loop testing systems (160,161) are coupled via a data communication network (140) in a manner that allows any front-end computer to communicate with any loop testing system. Users of the system control access and test from consoles having the capability of establishing independent communication paths over the national dial network for interactive tests on loops accessed through standard test trunks.

Abstract: A mechanized system distributing the access, test and communication functions to the point of testing, typically the centralized switching facility serving the telephone loops and equipment to be tested. Computer (200) stores information about each subscriber loop in the geographical area served by a system. Front-end computers (220,221) interact with computer (200) to retrieve pertinent data regarding loops to be tested. Each switching facility in an area includes a loop testing system (e.g., 160) that implements the required functions. The communication functions residing in front-end computers (220,221) and loop testing systems (160,161) are coupled via a data communication network (140) in a manner that allows any front-end computer to communicate with any loop testing system. Users of the system control access and test from consoles having the capability of establishing independent communication paths over the national dial network for interactive tests on loops accessed through standard test trunks.

Abstract: A toroidal, saturable core reactor (14) is connected in series with the conductors (11,19 and 13,21) of a transmission line. A termination network (16) is connected across the transmission line conductors (19,21). In response to an a.c. test signal transmitted from a generator (48) on one of the conductors (11), a series of voltage spikes are induced at the reactor (14) and superimposed on the a.c. test signal. The superimposed a.c. test signal is returned through the termination network (16) and the other line conductor (13) to a current detector (50) for detecting the spikes. A d.c. signal is then applied along with the a.c. signal. If there is a fault beyond the reactor (14), the spikes will be displaced from their expected positions. If there is a fault before reactor (14), the spikes will not be displaced. For ease in signal discrimination against noise, the d.c. signal is modulated.

Abstract: A mechanized system distributing the access, test and communication functions to the point of testing, typically the centralized switching facility serving the telephone loops and equipment to be tested. Computer (200) stores information about each subscriber loop in the geographical area served by a system. Front-end computers (220,221) interact with computer (200) to retrieve pertinent data regarding loops to be tested. Each switching facility in an area includes a loop testing system (e.g., 160) that implements the required functions. The communication functions residing in front-end computers (220,221) and loop testing systems (160,161) are coupled via a data communication network (140) in a manner that allows any front-end computer to communicate with any loop testing system. Users of the system control access and test from consoles having the capability of establishing independent communication paths over the national dial network for interactive tests on loops accessed through standard test trunks.

Abstract: Circuitry, and associated methodology, for locating resistive shunt faults on a cable pair comprises DC source (120) and current sensors (121,122) which provide measured information utilized to estimate the resistance of the pair between the fault and a test position. In locating faults of a single-sided nature, two sets of measurements, either absolute or ratio type, are effected from the test position with the pair shorted at a point beyond the fault. In locating double-sided faults, three sets of current dependent measurements are taken at the measurement point. A reference pair is required for double-sided faults, and various strapping arrangements between the pair under test and the reference pair are required at a point beyond the fault depending on the required set of measurements.

Abstract: Apparatus, and associated methodology, for testing an open in a pair from a shielded, multipair cable contaminated by water to correct the measured distance to the open from a measurement point and thereby obtain the true distance comprises: means (501) for applying an AC source (100) to the mate (101) of the open conductor (102); means (503,504) for detecting the resultant voltage induced on the open conductor through the capacitive coupling effects of the pair; and means (510) for determining the percentage length of the pair affected by water from the source and resultant voltages and for estimating the true distance by correcting the measured distance as a function of this percentage.

Abstract: Circuitry for converting a transfer function characteristic into a specified driving point impedance using feedforward techniques comprises: a directional coupler (90) having input, transmission and reflection ports; and unidirectional signal transfer means including transfer network (91) and amplifier (92) connected in cascade between the transmission and reflection ports. The impedance level of the transfer network is adjustable and is compensated for by the amplifier. A high impedance level allows for small element values for certain components such as capacitors so that a wide frequency band driving point impedance may be realized with integrated circuits. Further decrease in capacitor values is achieved utilizing capacitor magnification. The driving point impedance may be realized in balanced or unbalanced-to-ground fashion.

Abstract: Portable test apparatus utilized to access a field of test points comprises either a single access tool (100) or a multiple access adaptor (200) depending on the mode of testing required. Tool (100) is usually employed for accessing the field to effect aperiodic testing whereas adaptor (200) is generally used for planned test activities.Tool (100) comprises body (111), guide assembly (150) and cover plater (170) which house clamp assembly (130) and pin contact assembly (180). Clamp assembly (130) operates in scissor-like fashion for engaging and disengaging tool (100) from test field grips (401). Spring-loaded pins (181) penetrate apertures (403) within the test field to contact the test points.Adaptor (200) comprises body (211), center panel (240) and guide (260) which enclose pin contact assembly (280); in addition, cam-lever drive assembly (210) attached to body (211). Drive assembly (210) has means for grasping a frame (50) associated with the test field so as to draw body (211) towards frame (50).

Abstract: Apparatus augmenting a wave soldering machine for mitigating warpage of a printed wiring board after it is processed by the soldering machine comprises heat dissipation means (200) and cooling means (202). The dissipation means directs a first gaseous stream over the a narrow, transverse strip on the underside of the board as it exits a crest of molten solder supplied by the soldering machine. The stream solidifies any liquid solder without disturbing the solder joints. The cooling means directs a second gaseous stream to substantially the centerline region of the board as it exits the dissipation means. The seriatim arrangement of heat reduction means produces a cooling characteristic which is the inverse of the temperature characteristic caused by the soldering operation.

Abstract: Circuitry (100) for providing impedance compensation between a source impedance (501) and a load impedance (505) which is proportional to the source impedance comprises: a pair of directional couplers (200 and 300), each coupler including bidirectional transmitting and receiving paths and a unidirectional path coupling these paths; means (121) for cascading the transmit path of one coupler to the receive path of the other; and unidirectional amplifier (400) for interconnecting the remaining bidirectional transmission ports. The impedance match to the source is obtained by adjusting the amplifier gain in correspondence to the number of essentially identical terminations that are bridged to form the load impedance. Means (510-515) sense the number of active terminations and transmit this information to the amplifier so the appropriate gain setting may be established.