Abstract: The quality of voice signals transmitted by a telephone station set, or similar device, are enhanced in accordance with the steps of the instant method before such signals are delivered to a receiving telephone station set by restoring the level of speech energy attenuated by the transmitting set, in which such restoration is performed at a point along a telephone connection between the transmitting and receiving telephone stations, for example, at a point within a telecommunications system which establishes the connection.

Abstract: Each line wire is separately biassed by DC potentials feeding Inputs of the respective line wire driver amplifiers, the first potential (BA) being nearer ground and the second at an equal distance from the negative supply used to power the amplifiers so as to allow a suitable AC swing for the speech and metering signals also feeding the inputs of the amplifiers. The second potential (BB) is obtained from a DC synthesizing loop voltage and to which is added (OA6) the first potential, both potentials being also combined (OA5) to control a switched mode DC/DC converter delivering the negative power supply. In addition to both potentials being filtered with reference to ground, another measure reducing noise relies on AC signals push-pull outputs driving the amplifier inputs, also in push-pull through four resistances.

Abstract: A white noise suppressing circuit for suppressing white noise contained in a received voice of a speaker telephone apparatus includes a filter for suppressing white noise contained in an aural input signal input to an aural signal line, a switch for short-circuiting the filter, a detecting circuit for detecting the aural input signal, and a comparator for comparing an output of the detecting circuit with a preset voltage and for controlling the switch on the basis of the results of the comparison. When it is determined by the comparator that there is a voice input, the switch is short-circuited to make the filter inoperable. When there is no voice input, the switch is opened so as to make the filter operate.

Abstract: A circuit for interfacing a host telephone system having a trunk line pair with a central office line pair and an additional circuit line pair includes a loop current monitor circuit for monitoring the host telephone system trunk line pair which is normally connected to the central office line pair. The loop current monitor provides a status signal output indicating the presence or absence of loop current. A relay controller receives the status signal and provides a relay control signal and a hold signal. A relay selectively connects the host telephone system trunk line pair to the additional circuit line pair in response to the relay control signal when loop current is detected after the host telephone goes off-hook. A hold termination circuit receives the hold signal and traps any loop current signals which may be detectable over the central office line pair.

Abstract: A telephone network interface device comprises a base structure, a protector assembly disposed within the base structure and a cover on the base structure. The device also includes a telephone jack and terminals to which a telephone subscriber's wiring can be connected. The combination of the base structure, cover, telephone jack and terminals comprise a stand-alone unit which can be mounted in a variety of enclosures when installed at a telephone subscriber's premises.

Abstract: A signal detecting device capable of determining whether automatically dialling transmission is to be carried out by detecting an identification signal sent from an exchange system via a telephone line. The frequency variation of the identification signal is constant since the identification signal is a composite wave of a plurality of constant frequency signals. A pulse train having substantially a constant number of pulses can be obtained by comparing the level of the identification signal provided from the telephone line with a predetermined reference voltage by voltage comparators. Frequency counters count for a constant time period the number of pulses included in the pulse train provided from voltage comparators. According to the count result output of frequency counters, a determining circuit makes determination whether an identification signal is received or not.

Abstract: An interface for translating signals from a ISDN terminal to an analog telephone terminal including apparatus for separating ISDN signals into control and data signals, apparatus for utilizing the control signals to generate tone signals for transfer to a telephone line, apparatus for translating the digital control signals into signals controlling the transfer of data from digital to analog form, apparatus for translating digital signals in ISDN format into analog signals under control of the apparatus for translating the digital control signals into signals controlling the transfer of data from digital to analog form, apparatus for translating control signals in analog tone format to digital signals for controlling the transfer of signals to an ISDN terminal, apparatus for using the control signals for controlling the transfer of data from analog to digital form, and apparatus for translating analog signals into digital signals in ISDN format under control of the digital signals for controlling the transfer

Abstract: A circuit arrangement converts signals and information between analog junction lines and digital terminal devices in communications exchanges. A decentralized control device is provided in order to process and pass on switching criteria and codes received and sent to the respective analog junction line, inside and outside the audio frequency band, the circuit arrangement including a plurality of line interfaces, each coupled directly to a respective one of the decentralized control devices, for the switching criteria and codes to be exchanged outside of the audio frequency. At least one digital signal processor is provided for processing the codes to be exchanged within the audio frequency band, the digital signal processor being looped in via a hybrid connection and converter in a speech path which cooperates with the control device.

Abstract: Changes in a telephone subscriber line voltage are detected in a telephone set by supplying a voltage dependent upon the subscriber line voltage to a potential divider having first, second, and third tapping points, the second tapping point being between the first and third tapping points, and comparing the voltages at the first and third tapping points with a smoothed version of the voltage at the second tapping point to produce pulses at respective terminals when the line voltage is falling or rising. An algorithm is described for responding to the pulses to distinguish changes in hook state of another telephone connected to the same subscriber line from interfering signals. The arrangement facilitates remote release from hold and privacy indication functions for the telephone set.

Abstract: A push-button telephone dialing device for a telephone set has a push-button keypad with a plurality of keys which include a hold function key, and a telephone dialing integrated circuit including a key input signal generator wired to the push-button keypad and producing an appropriate key input signal corresponding to a key pressed on the push-button keypad. The key input signal generator produces a hold function key input signal whenever the hold function key is pressed. The telephone dialing integrated circuit further includes a speech network interrupt circuit which receives the hold function key input signal from the key input signal generator. The speech network interrupt circuit is wired to and controls the operation of a speech network of the telephone set.

Abstract: A digital line card for interfacing a remotely located digital telephone to a central office system by a two-wire connection is disclosed. The digital line card consists of a line interface connected to the two-wire connection. The line interface provides a full duplex transmission link with the remotely located digital telephone over the two-wire connection. A buffer is connected between the line interface and the central office system. The buffer converts data between the line interface and the central office system. The line card further comprising a protocol controller connected to the line interface. The protocol controller performs a packet protocol for communications with the remotely located telephone.

Abstract: An ear piece device configured for being supported in the ear and providing a microphone which is sensitive only to sounds conducted within the skull of the user is contained within a housing which is configured at one end to fit snugly at the ear canal of the user, but not to extend within the ear canal. A microphone element is coupled within the housing in a position such that the microphone element is separated from contact with the skull of the user by the housing. This microphone element includes an inertial platform which has sufficient inertial mass to substantially resist movement associated with the housing by reason of audio vibration and which is cantilevered at one end within the housing and includes signal means for generating a signal representing vibrations transferred into the housing in the form of audio vibrations from the user. This signal is supplied to an audio circuit for processing and reproduction of the user's voice.

Abstract: A portable telephone system is disclosed in which a plurality of i-th class exchanges, which accommodate key service units of a plurality of portable telephone sets present in each service area, and at least one (i+1)th class exchange which accommodates the plurality of i-th class exchanges through junction lines, are stratified to form an exchange system so that i=1, 2, 3, . . . , and so that the (i+1)th class exchange covers all service areas. The exchange system has a function whereby information which specifies the home area of each portable telephone set and the portable telephone set in distinction from each other is registered in the i-th class exchange and the (i+1)th class exchange, which administer the home area.

Abstract: In a telephone alerter a transducer disc is held onto a printed circuit board by an annular housing which is detachable from the board. The housing has spaced feet which are received through apertures in the board and the housing is then rotated to engage the feet with one side of the board and hold the housing in position. The transducer disc is easily removed by rotating the housing in the opposite direction to withdraw it from the printed circuit board. Preferably, the disc is retained within the housing by an O-ring retainer which is compressed between the printed circuit board and the disc. Upon removal of the housing, the disc and retainer may then be immediately withdrawn from the housing.

Abstract: Measuring the programming resistor in a data jack by placing the resistor in an AC voltage divider circuit via a transformer. An AC voltage (preferably generated by the modem's own transmitter circuitry) is applied to the voltage divider circuit, and an AC voltage measurement (preferably made by the modem's A/D converter) provides the resistance of the programming resistor. Matching the low-pass filter impedance characteristic of a local loop with a network having a matching low-pass filter characteristic, while also compensating the received signal with a compensation network having a high-pass filter characteristic, to reduce the frequency dependent gain effects caused by the matching network and/or the local loop.

Abstract: In a method and configuration for forming a line termination at two line terminals of a telephone line, alternating signals are separated from direct signals applied to line terminals, referred to a reference variable and added to a transmission signal from a transmission terminal to form a resultant actual-value signal. The resultant actual-value signal is compared with a reference signal at a gain-controlled amplifier. The reference signal is formed with an impedance transmission function corresponding to a given termination impedance by weighting the alternating signal at one of the line terminals being connected to a current sensor resistor. A current between the line terminals is determined with a control transistor associated with the current sensor resistor. The control transistor is controlled with the gain-controlled amplifier.

Abstract: A line unit, used in a line shelf having a line shelf processor and common logic, is provided with an EEPROM device for storing information relative to the line unit. The stored information includes line unit type identification codes, auto provisioning data, gain and equalization adjustment data and signaling translation tables. The data contained within the EEPROM may be utilized by the line shelf processor to provide automatic initialization and provisioning of the line unit when first inserted into the line shelf, and automatic signaling translation so that line unit signaling becomes compatible with a transmission facility connected to the line shelf. The need for factory preset resistors installed in the line unit may be eliminated by storing within the EEPROM a required gain setting.

Abstract: Digital-type hands-free telephone apparatus is provided including a microcontroller, an audio board and a COFIDEC circuit, in which the microcontroller permanently calculates the average values of 16 successive samples on each one of the send and receive channels and deduces therefrom which channel is to be enabled while attenuating the other using tables provided in ROM memory.

Abstract: A hybrid balance and combination codec filter circuit used in a subscriber line interface circuit over which a connection is established between a digital switching network and a subscriber instrument. The hybrid balance and combination codec filter circuit in combination includes a transmit section that converts differential voltage audio signals representing voice transmissions transmitted from the subscriber instrument into Pulse Code Modulated (PCM) encoded digital data, for transmission to the digital switching network. A receive section converts PCM encoded digital data representing voice signals switched through the digital switching network into differential voltage audio signals for transmission to the subscriber instrument. An included hybrid balance and echo cancellation section connected between the transmit section and the receive section reshapes the audio band signals output by the receive section.

Abstract: A connecting line is provided between a switching center and a subscriber for transmission of telecommunication signals. At the subscriber's end of the connecting line, there is located a device which, in addition to other passive and active units, includes a transformer, whose output winding is subdivided into two partial windings of identical size. A first capacitor, a switch and a second capacitor are connected in series between the partial windings. To prevent distortions of the dial pulses, a connecting line between the switch and the second capacitor is connected with a reference potential of the circuit arrangement.