Abstract: A telephone station set (S1) is arranged to communicate voice signals over a voice communication pair (V1) and to communicate ringing, switchhook supervision and visual signaling over a separate signaling pair (C1). An amplitude and polarity modulated alternating voltage on the signaling pair (C1) provides current flow in one direction for visual signaling while distinguishable amounts of current flow in the opposite direction to provide switchhook and ringing supervision. The switchhook supervision current and the ringing signal current both flow through a series connection of a buzzer (B1) and a break switchhook contact (SH2) in the telephone station set. An off-hook condition at the telephone interrupts current flow on the signaling pair (C1) providing a switchhook supervision signal while simultaneously terminating the ringing signal.

Abstract: A small program controlled communication system is disclosed having user changeable feature and line selection control. Associated with each station is a set of switches which are used to associate the various central office lines with the available nonlocking station pickup keys. The user, by setting the switches, can establish any line as a prime line and may select which other lines appear at the station. The setting of the switches also controls various other features available to the station, such as common audible, and privacy. The system is arranged such that the processor interrogates the switches periodically and translates the setting of the switches, which are human factors coded, into machine control codes which are stored in the main memory.

Abstract: A remote gain controlled optocoupled device is disclosed utilizing a DC reference voltage in the output section to compensate for variations in the optocoupling characteristics of the circuit. The DC voltage level output of the photodetector, which is a function of the light transfer characteristics of the circuit, is compared to a remotely controlled reference DC level. The output AC signal level, which substantially tracks the DC voltage output, is gain adjusted under control of the compared DC voltage levels.

Abstract: There is disclosed a clip for securing in mated relationship two-part connectors where one connector part is mounted to a panel. The clip is designed having an upper section which curves to fit over the top of the mated connector housing. The lower section of the clip, which is hinged to the upper section, contains a pair of tabs extending from the side edges. The tabs are folded backward to form slots which operate to hold the clip secure against the panel. The hinge is arranged to provide an additional slot so that the clip can secure connectors having differing heights.

Abstract: There is disclosed a flexible unitary retaining clip for use with two part electrical connectors. The clip locks around the mated connector by the snap action of folded sections and is released by externally directed outward pressure on a top section. The clip is designed with two mounting positions to accommodate different connector hood sizes.

Abstract: Call coverage problems are solved in a telephone communication system by arranging the system on a station orientation basis so that any call directed to a station on any line appearance at that station will be covered by a single button on any one of a number of other coverage station sets. Any other station may also have its calls directed to that same coverage station set and, if desired, to the same call coverage button on the covering set. By separating ringing signals and flashing signals and by handling each on a station basis, it is possible to allow both ringing and visual signals of the call if covered by one station, whereas if call coverage is handled by another station it can be arranged so that only visual signals will be provided.

Abstract: A communication conferencing arrangement is disclosed which relies upon the use of a plus/minus (+/-) nonlocking button followed by the operation of a button associated with any other line appearing at the station. If the operated line button is associated with a currently active line that line will be removed from the conference. If, however, the operated button is associated with a nonactive line (held or idle) then that line will be added, in conference fashion, with the communication leads of the enabling station. Provision is made to allow any number of added connections up to a preset maximum number at any station.

Abstract: A modulated RF carrier signal distributing arrangement, utilizing existing line circuits, is disclosed for providing entertainment signals to key telephone lines in the active noncommunicating (hold) state. The disclosed system utilizes an existing option connector on the line circuit for connection of a music receiver circuit. A centrally located transmitter circuit frequency modulates its own RF carrier with an externally supplied music signal and is wired to the existing common dc power to distribute the modulated RF signals to the receiver via the option connector on each line circuit. The receiver circuitry demodulates the RF signal and couples the resulting music signal directly across the hold bridge leads of the associated line.

Abstract: There is disclosed a protective coupler for use with key telephone line units (KTU) to provide isolation between the terminal equipment and the central office line. The protective coupler plugs onto the KTU option socket and establishes a dielectric barrier to protect the system from possible overvoltages, guarantees a balanced termination, and meets leakage requirements while remaining operable to pass control and voice signals between the network and station equipment. The central office side of the barrier contains a current sink for control purposes as well as a gain compensation circuit to adjust for varying distances from the central office.

Abstract: The disclosed T-type line compensation circuit reduces the gain and return loss variations when customer equipment is connected to a central office or PBX over telephone lines of various lengths. A linear resistor of a first series leg is thermally coupled, as a heat source, to a positive temperature coefficient (PTC) resistor of a second series leg. The shunt leg consists of a series connection of a bilateral zener diode, linear resistor, and varistor. The resistance value of both the second series leg and the shunt leg of the line circuit vary automatically with the direct current in the line to minimize gain variation due to telephone line length variation. The thermal feedback to the PTC resistor varies automatically with the direct current in the line to minimize return loss variations seen by the customer equipment.FIELD OF THE INVENTIONThis invention relates to a line circuit for compensating telephone loop line and return loss variations due to variations in line lengths.

Abstract: There is disclosed a protective coupler circuit of the circuit breaker type having a relay contact inserted in the communication line between the key telephone station and the central office in order to protect the central office line from hazardous voltages. A longitudinal unbalance detector is coupled with a metallic high voltage detector to control the relay operation. Circuitry is provided to operate in conjunction with the ring detection circuitry of the key telephone unit to insure proper circuit operation when ringing potential is present on the communication line even though that potential is over the threshold level of the hazardous voltage protector.

Abstract: A communication system call transfer arrangement is disclosed which relies on the establishment of two system access buttons on every telephone served by the system. The system access buttons are operational to originate a call to any station in the system over any idle link. A call on either access line can be added to any other currently active line on the telephone set. The system access buttons at all the stations operate such that an incoming intercom call will terminate on eitherbutton, and calls can be originated from the station by using either button. For call transfer purposes the system access lines are arranged such that when the station passes a call via the access line to another station and then goes on-hook, the system access lines become idle and are available for use by the station even while the transferred call is in progress.

Abstract: An assembly is disclosed for bridging pairs of closely spaced electrical terminals having a variety of predetermined spacings. The assembly consists of a pair of identical insulative body parts which have cavities therein for housing two identical contacts and conductive devices connected between the contacts. The contacts and the conductive devices are connected together and inserted into appropriate cavities of a first body part, whereupon the second body part is snapped together and sealed with the first body part. A cantilevered contact mount enables the contacts to deflect and mate with connector blocks having split blade-like metallic terminals of various predetermined spacings.

Abstract: A privacy circuit for use in a key telephone station set is disclosed. Using only a single relay, the privacy circuit operates to exclude the user from a busy central office line while allowing the user to gain access to an idle line. The privacy circuit is positive acting and cannot be circumvented by manipulating the keys and/or switchhook while at the same time allowing service to continue during a local power failure. Additional circuitry is provided to allow conference connections among key telephone sets equipped with privacy circuits.

Abstract: There is disclosed a communication system arrangement whereby the efficiency with which pooled facilities are used can be increased by reducing the number of lines that are dedicated to the pool. This is accomplished by making available to the pool, on a priority basis, lines that have been installed for other purposes, such as, for example, conference lines and private two-way lines. The system is arranged such that dedicated pooled lines have a higher priority than other lines which are available to the pool on a decreasing priority basis. In addition, each pooled set of lines at each station is given a visual indication using the system available lamp to indicate whether an idle line remains in the pool. This arrangement allows each station user to determine, without unnecessary seizure attempts, whether or not an available line exists in the pool.

Abstract: The disclosed switch mechanism consists of two toggle arm type linkages connected to a switch actuator, powered by a dual torsion bar spring, each linkage working in opposition to the other. Thus, a net resultant force is exerted on the switch actuator locating the associated switch mechanism in either of two stable positions with the net resultant force being equal to the difference between the forces generated by the two torsion bar spring arms and applied by the two toggle arms to the switch actuator.

Abstract: A key telephone system signal priority arrangement is disclosed wherein each type of call in a key telephone system is assigned a distinctive priority. When a call is directed to a station engaged in an existing lower priority call, a warning tone is given to both parties engaged in this existing call. The existing call is then automatically placed on hold while the preempting call is completed to the called station such that the called station can answer the preempting call "hands-free".

Abstract: A PBX call restriction arrangement is disclosed in which a plurality of call rerouting schemes are concurrently provided. The class of service assigned each station is used to define both the types of calls prohibited to the station and the rerouting treatment to be given an attempt by a subscriber at this station to make this prohibited type of call.

Abstract: A telephone station set interface circuit is disclosed which enables a conventional nonkey telephone station set to be used in place of an electronic key telephone station set for those subscribers in an electronic business communication system requiring only a call origination and a call reception capability.

Abstract: An intercom system for single-line customers is disclosed which utilizes the existing nonkey telephone sets and four-conductor wiring plan together with an additional adjunct per telephone and a common control unit. Hold, broadcast intercom, and their associated visual signals are controlled by each adjunct unit which is interposed between the associated telephone set and the existing four-conductor telephone cable. Normal voice signals and supervision are transmitted using one pair of the four-conductor cable. The second pair of the cable is used for signaling between the common control unit and the adjuncts as well as for supplying power to the adjuncts. The operation of a single nonlocking key at any adjunct places the system in the intercom mode and concurrently places an active central office line on hold. Conclusion of an intercom conversation is accomplished when all telephone sets go on-hook. A held central office line is then connected to the next party to go off-hook.