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...When G.G. Hubbard learned of his future son-in-law's invention, he called it "only a toy." His daughter was engaged to a young man named Alexander Graham Bell.
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| Number | Title | Issue Date |
| 7428404 | Communication apparatus with external activation of communications link Herein disclosed is a communication apparatus to be operative in combination with first and second external devices for respectively producing first and second information, comprising: first information receiving means for receiving the first information from the fi... | 09/23/2008 |
| 7406614 | Electronically implemented dynamic start up method for ports with inrush current limiting functionality A power over Ethernet controller comprising: control circuitry; at least one temperature sensor operatively connected to the control circuitry; and a plurality of electronically controlled switches responsive to the control circuit, each of the electronically contro... | 07/29/2008 |
| 7065204 | Method for transmitting charging signals via a data transmission path using resonance phenomena Method for transmitting charging signals via a data transmission path using resonance phenomena The invention provides a method for transmitting charging signals, in which an electrical resonance effect is provided, with an output current (100) being emitted ... | 06/20/2006 |
| 7027587 | System and method for deriving sealing current An adaptive unit that taps into an existing POTS line, DLC POTS line, DLC channel unit designed for sealing current outputs, or AC-DC transformer designed for sealing current output, to provide sealing current to a DSL circuit thereby avoiding having to deploy a sep... | 04/11/2006 |
| 6975172 | Smart voltage rail reduction audio amplifier An audio amplifier is provided that adjusts the supply voltage rails communicated to a power amplifier circuit according to the circuit's output. The amplifier compares the output voltage from the power amplifier to a predetermined voltage range to determine if the ... | 12/13/2005 |
| 6907267 | Loop-powered T1 radio A loop-powered T1 digital radio is coupled to a powered T1 wireline. The radio not only interfaces digital T1 communication signals with the line, but is configured to extract and convert electrical power from the line to voltages necessary for operating the radio. ... | 06/14/2005 |
| 6847718 | Remote power feed method and system A remote power feeding method allowing efficient remote power feeding into a network termination device in the event of a commercial power failure at a subscriber site is disclosed. When the commercial power failure occurs, a power failure signal is transmitted from... | 01/25/2005 |
| 6356623 | Method for communicating on an equipment network A method is provided for communicating on an equipment network. According to the method, a message is sent from a sending equipment unit to a receiving equipment unit as a signal having a nominal power. Whenever the signal is amplified by an intermediate ... | 03/12/2002 |
| 6175556 | Remote powered ethernet repeater A system and method for remotely powering an Ethernet network repeater through an attachment unit interface (AUI) between the repeater and a remote personal computer ("PC") or workstation. The AUI includes logic circuitry to detect when the Ethernet is su... | 01/16/2001 |
| 5642412 | Isolated high impedance, DC current sources for telecommunications applications An isolated, high impedance, DC current source is provided from a readily available AC type source. The DC current source includes an isolating transformer which receives the AC source signal and provides an isolated AC voltage signal therefrom, a resonan... | 06/24/1997 |
| 5412716 | System for efficiently powering repeaters in small diameter cables A system of impedance matching is provided to match the total impedance of the cable system to the total impedance of the powered elements such as the repeaters. The source impedance of the power supplies may be considered as part of the cable impedance. ... | 05/02/1995 |
| 5373554 | Telephone having separate power circuit for supplying power to speech network A telephone includes a speech network for transmitting an outgoing voice signal and receiving an incoming voice signal from a remote telephone. The speech network is not supplied with power from a telephone exchange through a telephone line but supplied w... | 12/13/1994 |
| 5307406 | ISDN power source detection circuit In an ISDN communications system, a remote station power detector circuit comprises a capacitor connected between center taps of transformers on the receive and transmit pairs of conductors. The capacitor stores energy delivered from a central DC power so... | 04/26/1994 |
| 5280526 | Transformer-less hybrid circuit An improved transformer-less electronic isolating transformer is obtained with an output subcircuit that outputs a controlled current rather than voltage. Specifically, the improved hybrid comprises an output drive subcircuit that receives an ac signal an... | 01/18/1994 |
| 4798969 | Power feed system in transmission line between terminals of three-terminal station A transmission line between terminals of a three-terminal station is branched by a branching unit and power is transmitted between the terminals of the three-terminal station and a power feed system in the transmission line including: a switch for switchi... | 01/17/1989 |
| 4771229 | Circuit arrangement for automatic connection of the remote feed current paths of a remote feed loop In a circuit arrangement for automatic connection of a remote feed current path of a remote feed loop fed from both sides for electrical loads with direct current series feed, a parallel circuit of a first four-terminal network comprising two feed outputs... | 09/13/1988 |
| 4719623 | Method of receiving time multiplexed signals together with energy requirements of receiver over a multiplex signal transmission path When a transmitter sends information signals time multiplexed in a single channel over a coaxial cable to a receiver, the expense necessary for synchronizing the demultiplexing operations to the multiplexing operations at the transmitter and for supplying... | 01/12/1988 |
| 4677646 | Dataset powered by control and data signals from data terminal A dataset apparatus is powered by voltages extracted from electrical signals passing between the data terminal apparatus and the dataset by circuits comprising a capacitor and diode combination. The transmitter of the dataset includes capacitance isolatio... | 06/30/1987 |
| 4649235 | Telephone circuit with a class-B amplifier output stage The telephone amplifier of an audio transmission circuit comprises a class-B output stage as a result of which the required supply current of this amplifier is considerably lower than with prior art telephone amplifiers. A distorting voltage produced by t... | 03/10/1987 |
| 4622442 | Electronic hybrid having synthesized impedance circuitry An electronic hybrid circuit for coupling a two-wire communication path to a four-wire communication path includes amplifier circuits having a reactive feedback path such that the output impedance of each amplifier is approximately zero ohms at DC and is ... | 11/11/1986 |
| 4622441 | Two-wire/four wire communication interface with noise rejection A subscriber line interface circuit is provided for a telephone system for interconnecting a two-wire telephone channel with a four-wire telephone channel. The circuit includes a pair of power amplifiers employing complementary circuitry and being coupled... | 11/11/1986 |
| 4606049 | Remote transmitter control system A remote transmitter system including a control station and a remote trantter station. The control station includes a variable frequency oscillator, a modulator, a parallel to series digital data converter and a DC power supply. The remote transmitter st... | 08/12/1986 |
| 4535303 | Driver circuit In a driver circuit including at least one integrated circuit amplifier, adapted to be interconnected with a subscriber's line of a telephone system, the operating supply for the amplifier includes a pair of series connected voltage supplies having a maxi... | 08/13/1985 |
| 4467472 | Diplexer for the separation of a signal and of a supply current A diplexer is disclosed for use in remotely fed intermediate regenerators or repeaters of broad-band transmission systems with coaxial cable sections. The diplexer has a high circulating attenuation at high frequencies. Since sections of the regenerator a... | 08/21/1984 |
| 4396808 | Telephone system with a ground or wire return A telephone system is described that includes a long line with a plurality of electrical conducting wires from a central office to at least one repeater and to at least one substation. Carrier frequency alternating signals are sent over a balanced pair of... | 08/02/1983 |
| 4309577 | Circuit for closing the remote feed loop of a series-supplied repeater A circuit closes a remote feed loop of a series-supplied repeater in a communications channel, in the event of an interruption in the transmission line, by means of a relay which senses an interruption in the feed current to close a shunt circuit. The shu... | 01/05/1982 |
| 4286123 | Bridge amplifier A four-transistor bridge amplifier is adapted for use as a bidirectional speech amplifier between a telephone line and an electronic telephone subscriber's instrument. The amplifier is powered from the line and includes two-transistor sections, one or oth... | 08/25/1981 |
| 4241243 | Power regulator for use with line signal repeaters which are remotely powered Operating power for line signal repeaters is fed over a transmission cable pair (signal line) which is susceptible to lightning strikes and, thus, to longitudinally induced currents in the DC power feed circuit. A symmetrical non-linear power regulator is... | 12/23/1980 |
| 4161008 | Protection circuitry for cable transmission system A protection circuit for a cable transmission system comprising a multipaired cable core surrounded by a conductive sheath wherein at least some of the cable pairs have one or more line powered repeater amplifiers connected in series therewith at discrete... | 07/10/1979 |
| 4160884 | Power regulation system for repeatered telephone transmission lines A telephone transmission system has repeaters spaced along both the transmit and receive legs of the transmission line, with a power supply for the repeaters including a current regulator having positive and negative supply lines connecting the power supp... | 07/10/1979 |
| 4110570 | Surge protection device for repeater A repeater suitable for use in submerged signal transmission systems, the repeater having inherent protection against power surges. The repeater includes a signal path including an amplifier and a separate path for powering the amplifier. The power path i... | 08/29/1978 |
| 4099036 | Remote power supply system for a coaxial line with repeaters subjected to the influence of external electric fields A remote power supply system is disclosed which is particularly for monocial transmission lines equipped with repeaters. It comprises at least one current transformer inserted between two sections of line in a local power supply circuit at each repeater.... | 07/04/1978 |
| 4099217 | Protection circuits A surge protection circuit for repeaters in a co-axial telecommunications cable where the power supply is through the cable conductors includes a cold-cathode discharge tube connected so as to provide a discharge path, when a surge occurs, for a capacitor... | 07/04/1978 |
| 4088850 | Remote supply system for a cable transmission line with repeaters subjected to the influence of external electric fields The invention relates in particular to remote supply with AC of repeaters a transmission line with symmetrical pairs. It provides a remote supply system in which the AC remote supply passes through a loop formed by two pairs of the line and in which each... | 05/09/1978 |
| 4064366 | Intrinsically safe telephone systems An intrinsically safe telephone system for use in mines or similar hazardous areas including a battery charging circuit arranged to supply charging current of a predetermined low value to the battery of an operational unit located in the hazardous area du... | 12/20/1977 |
| 4049929 | Apparatus for reducing the susceptibility of line signal repeaters to induced currents Apparatus for reducing the susceptibility of line signal repeaters to induced currents includes a zener diode/diode stack which provides the line repeater with a constant voltage drop when the DC line current is above the minimum required bias current. Wh... | 09/20/1977 |
| 3978391 | Direct current stabilizing device Current stabilizing device constituted by a two-terminal network in series with a load to be fed. The two-terminal network comprises, in series between its two poles a regulating transistor and a resistor, the regulating transistor being controlled by the... | 08/31/1976 |
| 3974345 | Negative impedance repeater with double amplification, for telephone lines A repeater for telephone lines, comprising two amplifier units serially connected and joined by an artificial line, the first unit having its input terminals connected to the secondary winding of a transformer of which the primary winding serves for conne... | 08/10/1976 |
