Matches 1 - 50 out of 108 1 2 3 >
Match Document Document Title
7548616 Termination device for a telephone line  
A termination device for a telephone line of a wire based telephone system, said termination device ( 30 ) comprising: a high pass filter ( 39 ) for separating signals within a frequency band used...
7447305 Method and arrangement for filtering of signals  
A filter ( 45 ) is passive and has a complex impedance which gives good impedance matching to the complex impedance of a transmission line. Because the filter is passive, it does not need to be...
7346149 Method and apparatus for reversibly correcting nonlinear impairments in a communications channel  
In a transmission line, nonlinear impairments resulting from imperfect splices are mitigated by providing a bias current that shifts the operating points of these impairments resulting in improved...
7181005 Telephone interface circuit  
An interface circuit that interconnects a terminal device at an extension station with the adjunct port circuit of a telephone of a business communications system (BCS), such as a digital PBX. The...
7043012 Method and apparatus for ring again feature for a telephone system  
A method and apparatus for an automatic ring again feature on a telephone set for a user that answers a telephone call not intended for that user is disclosed. If a user has answered an incoming...
7027590 Dynamic allocation of overhead voltage to support simultaneous transmission of signals on a telecommunication line  
Overhead voltage is allocated in a telecommunication system among different AC signals, such as POTS, on-hook transmission POTS, PPM and XDSL signals, communicated between a telephonic switch and a...
6980643 Fallback function telecommunications device  
The invention herein is fallback function communications device comprised of a microprocessor, utilized to perform a predetermined operation and processing of a predetermined input signal and then...
6393123 Method and modem circuit for determining connection status of a phone line  
A circuit for determining connection status of a phone line shared by multiple telecommunications devices, such as modems and phones, is provided. The phone line includes respective tip and ring...
6233462 Portable terminal device for automatically controlling transmitting voice level and calling sound level  
A comparing unit 18, when a radio unit 1 receives a radio signal, compares an ambient noise level detected by a noise sensor 17 with a preset threshold value. If the ambient noise level is smaller...
6020732 Flux cancelling transformer line circuit  
A flux cancelling transformer line circuit includes an AC current source that blocks AC current and passes DC current. The current source is connected between the primary and secondary windings of...
5991386 Method and arrangement for the connection of multiple terminals to one subscriber line of the telephone network, and a terminal  
In an arrangement for the connection of two or more terminals (1, 1') to one subscriber line (3) the terminals (1, 1') are connected to a chain so that the connection from the subscriber line (3)...
5970139 T1 channel bank control process and apparatus  
A technique for powering telephone lines using an unbalance current source and current sink; and a technique for improving attenuation/frequency distribution and return loss (impedance matching) of...
5912513 Method and apparatus for reducing power dissipation in DC termination circuit  
A DC termination device particularly adapted for use in a device coupled to a two wire telecommunications system. The termination device controls the tip-to-ring current through the...
5859906 Telephone switch hook interface circuit  
A switch hook interface circuit couples a subscriber telephone to a subscriber telephone line. This interface circuit comprises a source of an off-hook signal, having one state indicating an...
5729589 Apparatus and method for incoming call detection and alarm circuitry for cellular telephones  
An apparatus for use with cellular telephone to indicate an incoming telephone call to a user includes a cellular telephone battery pack having a circuit that generates a voltage signal with a...
5651052 Apparatus and method for incoming call detection and alarm circuitry for cellular telephones  
An apparatus for use with a cellular telephone to indicate an incoming telephone call to a user includes a cellular telephone battery pack has a circuit that generates a voltage signal with a value...
5539820 Protection of active telephone line interface circuits  
A telephone line interface circuit with d.c. amplifiers coupled to tip and ring paths is protected against transient voltages by a crowbar-type protection device coupled via a diode bridge to the...
5535272 Sensor circuit for a telephone line  
A sensor circuit for telephone line (10) includes a detection coil (12a) inserted in a telephone line (14). The coil generates a magnetic flux according to a line current which flows in the...
5515433 Resistance forward telephone line feed circuit  
A line feed circuit employing a low-inductance transformer, and providing a major portion of the terminating impedance as line feed resistors connected between a telephone line and the transformer...
5479499 Sensor circuit for voice/fax switch with cascaded amplifier circuit  
A sensor circuit for telephone line includes a line current detecting circuit (52, 54) which generates a detection signal in response to a line current flowing in a telephone line (20, 22). The...
5311587 Sensor circuit for telephone line  
A sensor circuit for telephone line includes a detection coil (52) inserted in a telephone line (22). The coil generates a magnetic flux according to a line current which flows in the telephone...
5289537 On-hook transmission circuit in cable line  
In an on-hook transmission circuit provided in a subscriber circuit connected between a subscriber terminal and an exchange, a constant-current source unit causes a constant current to flow in...
5138658 Subscriber line interface circuit providing regulated current  
A subscriber line interface circuit that provides regulated current to telephone subscribers in an improved manner reducing the amount of power required to operate while maintaining a constant...
5065088 Current sensor circuit  
A current sensor circuit for measuring by means of a Hall element the magnitude of a magnetic flux obtained in response to an input electric current and for generating a signal corresponding to the...
4896093 Electronic inductor  
To produce a high current carring inductor with a high inductance value in space normally too small, a transformer is chosen which meets space requirements and has a primary winding of sufficient...
4893331 System allowing selective connection of various types of external apparatuses to telephone set  
A system allowing selective connection of various types of external apparatuses to a telephone set, which system comprises a plurality of switching circuits connected to the external apparatuses...
4878244 Electronic hybrid circuit  
An electronic hybrid circuit includes a differential amplifier having its non-inverting input coupled via a resistor to a four-wire input port and via a coupling transformer to a two-wire...
4760379 Fail-safe high temperature alarm  
A temperature sensor located at a region being monitored controls an output switch that in one position when ambient temperature is below a predetermined temperature applies current to only a first...
4707673 Directional coupling transformer for bi-directional full duplex data bus  
A directional coupler transformer insensitive to data bus termination failures, includes a ferrite toroid core about which first through fourth windings are wound, the first and second windings...
4540853 Apparatus for detecting a loop during ringing  
The apparatus comprises a zero pass detector (2) for detecting zero passes in a voltage signal proportional to the line current to generate a pulse signal constituted by positive and negative...
4516070 Magnetic current sensor with offset and load correction  
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...
4480152 Methods and apparatus for protecting line relay contacts in a telephone switching system  
Line relay contacts (LR1 1 , LR1 2 ) are protected from power surges appearing on a telephone line (L1) during connect or disconnect of a station set (S1) from the line, by operating a hold relay...
4431869 Telephone line feed  
In a telephone line feeding arrangement, the line current is monitored by a multi-resistor network (R p R s ) and the output of the network applied to the inputs of an operational amplifier (A3)....
4389543 Telephone-activated audio control circuit  
The inputs of an operational amplifier are connected across a telephone line and bridged by a capacitor. The output of the operational amplifier drives the coil of a relay via an intermediate...
4355206 Ringing control device  
A ringing control device for a group of subscriber lines served by a connection network, comprising a relay for each line, the connection network providing a ringing control signal and a timing...
4355209 Programmable line circuit  
A circuit which can perform a plurality of sensor functions relating to telephone subscriber supervisory circuits. These functions can occur before and after ringing current is applied to the...
4310724 Current detector circuit  
A current detector circuit, preferably for use in telephone equipment, to detect the on-hook and off-hook conditions of of such equipment, includes two equal transformers which have primary coils...
4300021 Line circuit controlled by a hall effect device  
A circuit which performs both the supervisory functions and transmission functions of a line circuit under control of a Hall effect device. A Hall effect device operates in the magnetic field...
4278939 Electromagnetic arrangement for measuring electrical current  
A line current measuring arrangement employs two separate toroidal cores with line windings and control windings. The line windings cause equal amounts of the same polarity of magnetizing intensity...
4278938 Electromagnetic arrangement for measuring electrical current  
A line current measuring arrangement employs a single toroidal core with line windings, control windings, and a sense winding. The line windings cause an amount and polarity of magnetizing...
4274051 Electromagnetic arrangement for measuring electrical current  
A line current measuring arrangement employs two matched toroidal cores with line windings, control windings, sense windings, and feedback windings. The line windings cause equal amounts of the...
4237345 Transformer with integral reed contact  
A magnetically operated switch especially useful in telephone applications includes a transformer having a plurality of windings on an E-frame core and a reed switch magnetically coupled to the...
4166928 Loop, dial pulse and ring trip detection circuit  
A circuit which detects the presence and absence of a telephone subscriber loop, before and after ringing current is applied to the loop. Coils functioning as magnetic field generating devices and...
4119806 Subscriber's line equipment for a telephone exchange  
A subscriber's line equipment for a telephone exchange for replacing equipment comprising a telephone transformer or chopper, comprises a telphone line supply circuit comprised of two constant d.c....
4118597 Method and apparatus for detecting direct currents in a transmission line  
An electromagnetic sensing apparatus includes one or more magnetic cores coupled by windings to a pair of transmission line conductors for sensing the presence, and in some cases the magnitude and...
4110636 Feeding bridge  
A bridge circuit provided with an isolation transformer having four primary windings which are connected such that the voice currents do and the supply currents do not generate a resulting flux in...
4104488 Subscriber line circuit  
Telephone subscriber line circuits and an all-electronic telephone exchange are described wherein Hall effect devices are incorporated to detect line looping, dialing and ring-trip.
4103112 Telephone line circuit with differential loop current sensing and compensation  
The invention provides a telephone line circuit in which the likelihood of exposing circuit devices in an associated switching facility to potentially damaging currents or voltages is greatly...
4099032 Loop current detector  
A ground start loop current detector is used to monitor the loop current in a telephone subscriber loop when the subscriber requests service by grounding one line of the loop (ground start), when a...
4075431 Speech path system  
A speech path system for a telephone exchange having crosspoint switches of a speech path network comprising semiconductor switching devices of four or more layers, including a memory circuit for...
Matches 1 - 50 out of 108 1 2 3 >