Abstract: A two-wire/four-wire converter for coupling a two-wire communications path carrying analog transmission and reception signals to a four-wire communications path having a two-wire transmission path carrying digital transmission signals and a two-wire reception path carrying digital reception signals, includes an analog/digital converter having an input coupled to the two-wire communications path and an output coupled to the two-wire reception path. An adder has one input connected to the two-wire reception path and another input connected to the two-wire transmission path. A digital filter with an adjustable communications function generates a predetermined terminating impedance for the two-wire transmission path. The digital filter has an input connected to the output of the adder and an output. A subtractor has one input connected to the output of the digital filter, another input coupled to the output of the analog/digital converter and an output.

Abstract: A subscriber circuit has, in a subscriber line section thereof an in-phase induced noise suppressing circuit which is made up of two series connections of a capacitor and a non-linear element. When an intermittent high-voltage signal is being propagated on another subscriber loop, the noise suppressing circuit suppresses it to thereby prevent it from being transmitted to terminal equipment as noise. Since the degree of suppression of the in-phase induced noise can be limited as desired, the subscriber circuit is advantageously applicable to terminal equipment or line equipment having a line interface implemented as an LSI integrated circuit.

Abstract: A voice-band receive amplifier for telephone handsets that mitigates loud sidetone and acoustic sing. A receive channel (30) with amplification and voice-switched attenuation is disposed between a receive port of a telephone network (80) at terminals (1a), (1b), and an electro-acoustic receiver (20). A transmit channel (70) having voice-switched attenuation that varies inversely with the receive channel attenuation is disposed between a transmit port of the telephone network at terminals (2a), (2b), and an acousto-electrical microphone (10). A controller (60) with an output lead connecting to the transmit and receive channels has an input lead connecting to the microphone, and an input lead connecting to the receiver. The controller provides a varying DC control signal at its output lead in response to varying levels of transmit and receive signals appearing at the input of the controller. Receive signals are attenuated when transmit levels are at or above a predetermined threshold.

Abstract: In a voice processing system employing the telephone communications network, any echo of an outgoing signal is substantially eliminated from the incoming signal by appropriately combining an appropriate version of the outgoing signal with the incoming signal so that there is destructive interference with any echo of the outgoing signal. To determine the appropriate version of the outgoing signal to be combined with the incoming signal, a brief training signal is applied to the telephone transmission line. The echo of this signal returned by the transmission line is stored and convolved with the time-inverse of the training signal to produce a function which approximates the impulse response of the transmission line. This function is thereafter used to produce the version of the outgoing signal which is combined with the incoming signal for echo cancellation.

Abstract: An over-current verifier circuit used in a Subscriber Line Interface Circuit (SLIC) for validating an over-current condition on a subscriber loop comprising a first counter connected to the SLIC disposed to receive an oversense signal from the SLIC. The first counter begins counting when the oversense signal is received and produces an output signal when the oversense signal is still active after the counter finishes, denoting a dc over-current in the subscriber loop. A timer circuit connected to the SLIC also receives the oversense signal. The timer is arranged to begin counting when the oversense signal is received. A second counter further receives the oversense signal and is advanced by one count on the high to low transition of the oversense signal. The second counter produces an output signal when three counter advances are produced before the timer times out, denoting an ac over-current condition.

Abstract: A method and circuitry for reducing noise is provided. The circuit receives a digital data signal at its input (26). The signal is input to a magnitude evaluator (28) and a pass/squelch circuit (30). Magnitude evaluator (28) samples the digital signal and controls an integrator (36) according to the magnitude of each of the samples. Integrator (36) averages the magnitudes over time. If the signal is a noise signal, integrator (36) toggles a switch (40) to activate pass/squelch circuit (30) to squelch the digital data at its input (29). If the signal is a valid signal, then integrator (36) toggles switch (40) to deactivate pass/squelch circuit (30) to allow the digital data to pass therethrough to destination device (44).

Abstract: Apparatus for eliminating the need to repeat dial the same area code on a given long distance call. The apparatus detects when a subscriber wishes to implement a long distance call. Upon detection of the start of a call, the apparatus automatically displays the last area code dialed. The subscriber if desiring the last area code merely dials seven digits. The apparatus recognizes that the subscriber has selected the last area code to cause the last area code dialed to be transmitted prior to the transmission of the seven digits thereby completing a telephone number. If the subscriber does not wish to utilize the last area code dialed he first dials a "1" and then dials in ten digits and the proper digits are transmitted with the area code digits being replaced in the area code storage memory.

Abstract: A telephone circuit arrangement allows the use of a (high voltage) dialler chip (3) without a mode select output in a low voltage telephone. A filter (R1,C1) derives control signals from the DTMF output of the dialler chip. The control signals switch a control switch (TR1) connected to the Mode Select input (MS) of a transmission circuit (2) and the DTMF signals are applied to an input (T1) of transmission circuit (2). This enables the use of a dialler chip without a dedicated mode select output in a circuit which normally requires a dialler chip with a mode select output.

Abstract: A telephone set is provided enabling seizure for originating and terminating calls of a telephone line connected thereto to be performed as well as release thereof, as the result both of a first command produced by a first switching entity actuated from the handset of the telephone set as well as via a second command produced by a second switching entity that is able to be actuated independently of the handset, switching entities producing the commands via individual communication establishment elements which are inserted in parallel in a loop which links, via the controlled power feeding arrangement, the output terminals of a first diode bridge, the input terminals of which are connected to the two line wires via a protection circuit, together with a second diode rectifying bridge, performing actual rectification, linked via capacitors to the output of the protection device, in parallel with the first diode bridge, and adapted to power a microprocessor and relevant circuits of telephone set circuitry, via a

Abstract: A weatherproof telephone terminal apparatus includes a terminal assembly having a pair of terminal members included therein suitable for splicing insulated telephone wires of the same or different wire sizes in a single housing which is impervious to atmospheric conditions and may be used indoors and outdoors and may be installed in a clamshell-like housing, thereby eliminating the need for conventional splicing techniques.

Abstract: A SLIC includes in separate and distinct contacts for the output of a tip and ring line driver and their feedback resistors to the balancing resistor of the appropriate tip and ring line. Thus, a Kelvin contact arrangement is produced providing a compensation for the contact resistance of a single connection.

Abstract: A communication system receives data from a portable device without using a conductor. The data-receiving side obtains electric power from the outside. The portable device obtains electric power from its internal power supply or the data-transmitting side.

Abstract: 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 current source. The current to the telephone subscribers flows through a switching transistor, an inductive storage element, sensing resistors and a transformer. The desired operating characteristic is obtained by cycling the switching transistor. The switching transistor is cycled on at a preset interval causing the telephone subscriber current to flow from the switching transistor. The switching transistor is cycled off in response to an increase in the telephone subscriber current as sensed by the sensing resistors thereby causing the current to flow from the inductive storage element.

Abstract: In a network of interconnected wireless networks and wired telephone networks, there is provided a mechanism for sustained association of users with communications paths. It comprises: upon an attempted use of an unassociated telephone, identifying oneself to the network (via the wireless network) and activating one's telephone line by keying one's own telephone number through the telephone keypad, locating his telephone line by monitoring unassociated lines for activity, and the one so identified receiving a sustaining association (for more than a few communications) with the telephone line so located.

Abstract: An automatic dialing machine adapted to a facsimile machine having a telephone function comprises: a device for displaying an input number; a memory for storing part of telephone number and a coded number corresponding thereto; a speed dial key for inputing the coded number; a ten-key set for inputing a non-coded number; and a controller for displaying on the display device the coded number and non-coded number in turn and in series as they are input respectively from the speed dial key and ten-key set and further for performing a real-phone-number-dialing based on the displayed in-series number.

Abstract: An echo canceller and a communication apparatus employing the same, are capable of stably reproducing sounds other than a received sound during a speech through a telephone and the received sound is heard by the other party to the speech. The echo canceller includes first and second input terminals and first and second output terminals. An echo path between the first output terminal and the second input signal terminal is adaptively estimated. A signal component inputted through the echo path is cancelled from a signal inputted to the second input terminal. The canceller further includes a signal mixing means for mixing a plurality of signals inputted thereto.

Abstract: A cellular telephone dialing controller comprising an operator switch, a state machine, digitally stored audio prompts, and a Dual Tone Multi-Frequency signal generator, in which at each dialing step the operator hears sequentially the numerals zero, one, etc. and the operator "dials" by closing the operator's switch when the proper number is played. At completion of "dialing" the entire phone number is audibly replayed for operator approval, after which the call is automatically initiated, including the generation of Dual Tone Multi-Frequency as well as Off-Hook/On-Hook control signals, the entire dialing operation being completed without visual participation or use of the operator's hands, thereby ensuring driving safety.

Abstract: A reciprocal impedance conversion network is disclosed. Such conversion network preferably is used in a reciprocal negative impedance repeater for the nonloaded cable facilities of a telephone system. Two independent voltage sources for generating reciprocal negative impedance are connected between a first port and a second port. The first port is operably connected to the first voltage source such that a series negative impedance appears at that port. This port is specifically connected to the switching equipment of the telephone system. The second port is operably connected to the second voltage source such that a shunt negative impedance appears at that port. The second port is specifically connected to the nonloaded cable facilities of the telephone system. The invention further provides a frequency dependent gain circuit which is useful for equalizing the losses along the nonloaded cable facilities.

Abstract: A dialing confirmation tone (DCT) output apparatus including a variable attenuator connected between a DCT generator and an adder adding a received voice signal and a dialing confirmation tone. The attenuator attenuates the confirmation tone based on a control signal from a control circuit. The control circuit produces the control signal using a conversation condition signal and a receiving situation signal. The conversation condition signal is provided from a conversation condition detector and indicates whether conversation is taking place or not. The receiving situation signal is provided from an earphone jack circuit and indicates whether or not an earphone is used for outputting the added signal. The attenuated confirmation tone can be heard while conversation takes place or the earphone is used.

Abstract: A loudspeaking telephone station (speakerphone) includes a loudspeaker and one or more microphones within the same housing. The microphones are directional, each having a polar response characteristic that includes a major lobe, one or more side lobes, and nulls between pairs of lobes. The loudspeaker is positioned in the null of the polar response characteristic that resides between the major lobe and an adjacent side lobe. The microphone apparatus is positioned so that its major lobe is aimed in a direction that is generally perpendicular to the direction that the loudspeaker is aimed. Means are provided for increasing the distance between input sound ports of a first-order-gradient (FOG) microphone and thereby improving its sensitivity. A pair of such improved FOG microphones are used in assembling a second-order-gradient microphone. Full duplex operation is achieved when a pair of echo cancelers are added to further reduce the coupling between the transmit and receive directions of the speakerphone.