Hubbell Limited

Dmitry Levitan

Winston M Gadsby

Theodore A Schweitzer

Norman S Saah

Paul H Bock, Jr

An off-hook management telecommunication system comprising a DTMF detector, an encoder and a microprocessor located within a channel unit. The system allows the user to depress a selected sequence of keys during a line connection which indicate to the microprocessor to hold the line off-hook, via signaling to a central office, despite the fact that the telephone is being returned to an on-hook position. The line is held off-hook for a predetermined amount of time to allow the user to switch telephones.

Method and apparatus for off-hook management of plural subscriber premises devices connected to same telephone line

A plug-in circuit board assembly requires reduced insertion force during connection to a plurality of shorting contacts in a socket or receptacle. The connector portion of the circuit board assembly has a pair of end sections with beveled insertion edges that extend substantially perpendicular to the insertion direction of the circuit board. A shallow V-shaped cut-out with non-beveled insertion edges is located between the end sections. Electrically conductive fingers are carried by the connector portion of the circuit board assembly and extend toward the insertion edges of the end sections and V-shaped cut-out. The electrically conductive fingers adjoining the V-shaped cut-out are positioned to make contact with shorting contacts in the socket or receptacle, while the electrically conductive fingers of the beveled end sections are positioned to make contact with conventional (non-shorting) contacts in the socket or receptacle. The angled insertion edges of the V-shaped cut-out cause the electrically conductive fingers adjoining the cut-out to make contact with the shorting contacts in a sequential or progressive manner when the circuit board assembly is inserted into the socket or receptacle, thereby reducing the insertion force that would otherwise be encountered due to the absence of a bevel on the insertion edges of the cut-out

Plug-in circuit board with reduced insertion force

A two-wire channel unit or line card for use in a digital loop carrier (DLC) telephone system is disclosed. The channel unit is provided with a loopback test capability by using relays to open-circuit or short-circuit the input terminals of the hybrid circuit that couples the two-wire subscriber line to the separate two-wire transmit and receive paths within the channel unit. When open-circuited or short-circuited in this manner, the hybrid circuit couples voice frequency test signals between the receive and transmit paths of the channel unit, thereby allowing loopback testing to be carried out without providing a dedicated loss/gain circuit in the channel unit. An additional relay may be provided to vary the gain of an amplifier stage in the transmit or receive path of the channel unit during operation in the loopback test mode, in order to control the overall gain of the channel unit during loopback testing.

Two-wire channel unit with loopback test capability

A telephone system uses above voice-band ASK control and supervisory signals which are appended to digitally encoded voice by forcing the least significant bits to a selected level for transmission to the receiving end. At the receiving end, the ASK is regenerated by a circuit including special filter and a pulse generator. To eliminate audible noise resulting from the filter action, the ASK signal or the pulses from the pulse generator is shifted in phase by about 90.degree. before application to a filter. The result is significantly reduced noise.

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Fairfax Station, VA, United States of America

Dmitry Levitan