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American Telephone and Telegraph, Co.

American Telephone and Telegraph Corporation

Frederick Henry Koster

An arrangement for improved two-line hunting in crossbar switching systems is disclosed where the two lines are located in the same line link frame vertical group and vertical file. When the marker determines that the primary line is busy the marker is caused to recycle and to reseize the number group and retranslate the directory number of the primary appearance. When the marker re-obtains the equipment location information for the primary line appearance, it directly modifies one element of the translation information, illustratively, the horizontal group number, to obtain the equipment location of the auxiliary line appearance. Since the marker directly modifies the translation information furnished by the number group it is not necessary to assign a separate directory number to the auxiliary line appearance. The direct modification of the equipment location is performed by providing a selectively operable chain path in the operating path of the horizontal group seizure relays.

Crossbar line hunting arrangement

A circuit is provided for improving the manner in which tone signaling-to-dial pulse converters interface with prior art dial pulse registers. Instead of allowing the converter to operate the register's line supervisory relay, the converter directly operates the dial pulse counting relays of the register. In this way, changes in battery and ground potential and impedance which may be noticeable each time the conversion apparatus pulses the line relay are eliminated, and the line relay in the register is allowed, uninterruptedly, to supply battery and ground to the multifrequency signaling station throughout the duration of signaling. The direct operation of the pulse counting relays permits faster pulsing speeds because neither the distributed capacitance of the line nor the lumped capacitors used in connection with the line relay are in the pulsing path.

Tone signaling conversion apparatus

In a cable restoration system neon devices and light-emitting diodes are utilized to identify corresponding conductors in a broken cable by an arrangement that does not require the assistance of a lineman at the central office. The apparatus identifies a central office line by means of a neon device and ringing bridge arrangement which replaces the neon indicating bulbs used in prior art systems. After identifying a customer line at a cable break by using indicating devices in a conventional manner, a maintenance man at the break location dials the central office over a spare pair. When ringing is applied to the desired central office line, a glow discharge occurs in the neon device, which discharge heats a bi-metallic strip and causes the strip to move and establish a metallic short across the line. The short trips ringing extinguishing the discharge. The bi-metallic strip cools and the short is removed from the line. The maintenance man then applies a high frequency tone signal to the spare pair which signal appears on the desired line after passing through the central office. The tone is detected by a ringing bridge and used to illuminate a light-emitting diode which identifies the desired line.

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Granite Springs, NY, United States of America

Frederick Henry Koster