Abstract: A method and an apparatus for off-hook detection in a subscriber line interface circuit responds to a ringing signal which preferably lacks a DC component. A signal is generated that is a function of the line current through the subscriber line, and the time at which the signal exceeds a predetermined current value is measured. The measured time is compared with a predetermined time value, and an off-hook indication is produced in a processor depending on the comparison.

Abstract: A digital access arrangement, coupled between a data terminal equipment having a transmit line and a receive line and tip and ring lines of a network, having a circuit that provides polarity check, hook/switch control, and data modulation functionality. The circuit includes a controller and six controllable switches, each having a conducting state and a blocking state.

Abstract: The invention provides an apparatus and method and a device for echo attenuation in a telephone. According to the invention, the echo attenuation in the telephone is adapted to the background noise such that the ambient background noise in telephone (10) is measured with a noise detector (1) and the noise level is determined in a background noise measurement unit (2). The background noise that has been determined is used to set the attenuation parameters in parameter determining unit (3). The signal level received from the other subscriber's telephone (11) is measured in input signal level measurement unit (4). The feed signal of the telephone is attenuated in attenuation Control unit (6) on the basis of the attenuation values calculated, which have been determined from the attenuation parameters and the signal level received by the other subscriber in output signal attenuation determining unit (5).

Abstract: Telephone numbers along with alphanumerical identifications representing them are stored in a memory of a mobile phone. The number is selected with quick dialing so that the user first scrolls the identification corresponding to the required number on the display (11), after which the call is initiated by pressing the activation key. In the method of this invention the display is a touch-sensitive display, and a field (24) representing an identification on the display is divided into two or more sections (25, 26, 27) each of which corresponds to a different telephone number, e.g. to work (21), home (22) or to mobile phone (23). The required number is selected by pressing the column corresponding to the required section.

Abstract: An apparatus for detecting an off-hook condition on a telephone, the apparatus being connected to the tip line and the ring line of a telephone line, a first potential difference existing between the tip line and the ring line, the telephone line connected to the telephone having a handset. A circuit generates a difference signal representative of the absolute value of the first potential difference. A first comparator, responsive to the difference signal, generates a first indicator signal when the difference signal is above a first value corresponding to a maximum value of potential difference between the tip line and the ring line when the handset is off-hook. A second comparator, responsive to the difference signal, generates a second indicator signal when the difference signal is below a second value corresponding to a minimum value of potential difference between the tip line and the ring line when the handset is off-hook.

Abstract: In a telephone set having a receiver (42) and a loudspeaker (39), a switch circuit (37) selects supply of a reception speech signal, transmitted from a counterpart section (60), to the receiver or the loudspeaker in response to a selection signal. A first adaptive echo canceller (43a) produces a pseudo echo signal with reference to the reception speech signal. A controller (44) controls operation of the first adaptive echo canceller in response to the selection signal to optimize the pseudo echo signal. A first digital adder (35a) carries out a particular calculation between the pseudo echo signal and a transmission speech signal, relating to the transmission sound supplied to a microphone (46). The adder produces a particular calculation result signal representative of a result of the particular calculation. In accordance with the particular calculation result signal, a transmission is carried out towards the counterpart section.

Abstract: A dual mode mobile telephone apparatus includes an echo canceler. In a hands-free conversation mode, a received speech output from a loudspeaker is input to a microphone by circulate cross talk and transmitted to the destination side so that an acoustic echo may be generated. The echo canceler cancels the acoustic echo. A center clipper for eliminating a residual echo signal having a level lower than a preset level is provided at the output side of the echo canceler. Enabling/disabling operations of the center clipper are controlled in accordance with a volume control level for a reception signal and transmission/reception state detection signal from a voice switching circuit which controls gains of reception channel and transmission channel in the opposite directions.

Abstract: A digital loop system with a distributed architecture that provides telephone services with high reliability and quality and is cost-effective to install. The system is central office powered and uses a trunk unit interface to interface with a wide range of mechanical and electronic switches. The trunk unit interface connects to remote terminals via digital transmission lines. The remote terminals drive a large number of subscriber circuits through short subscriber loops. The distributed digital loop system employs sealed and environmentally hardened packaging for flexible outdoor installation. The electronic circuitry used by the remote terminals is divided into modules for flexible, incremental deployment of the system.

Abstract: A method of detecting narrow-band signals in an echo canceller to control the coefficient update process, echo suppression process, and the disablement of the echo canceller is provided. The method includes the steps of searching for the presence of a generic tone, searching for DTMF tones, searching for a 2100 Hz tone and, if a generic tone is found, searching for a dial tone. If a generic tone is detected on the far end signal, a tone flag is set which triggers the disablement of the echo canceller coefficient update process and the enablement of the echo suppressor process. If a 2100 Hz tone is detected, the echo canceller is disabled. If a DTMF signal is detected, DTMF flags are set which are used by the echo suppressor for suppressing the near end echo. Finally, if a dial tone is detected, dial tone flags are set which cause the disablement of the echo suppressor.

Abstract: A caller ID system is disclosed in which a prescaler is coupled between a source of a caller ID signal and a caller ID receiver, and a processor is coupled to the caller ID receiver. The prescaler is responsive to the processor for scaling the caller ID signal.

Abstract: A telephone ringing system in which one or more user-selected sound segments are received using the microphone portion of a telecommunications instrument, stored in digital or analog form, and audibly reproduced using the loudspeaker portion of the telecommunications instrument when a ring signal is detected to provide a distinctive, personalized indication of an incoming call.

Abstract: Telephone numbers along with alphanumerical identifications representing the same are stored in the memory of a mobile phone. The number is selected with quick dialing so that the user first scrolls the identification corresponding to the required number on the display (11). In the method of this invention the display is a touch-sensitive display (21). For each identification several alternative telephone numbers are stored in the quick dialing memory, for instance to work (W), home (H), or mobile phone (M). The desired number is selected and a call initiated by writing a gesture (23) corresponding to the required number on the display (21) or in a specified field of the display (24).

Abstract: To improve the signal to noise ratio of the receiver of a transmitting modem, the transmitting modem is equipped with the ability to cancel the far listener echo. Advantageously, doing so allows higher data rates or reduced error rates. Cancellation of the far listener echo is achieved by coupling the signal containing the in-phase, quadrature (also known as X and Y, or real and imaginary) components of the modem transmit signal to a far echo canceller that is included in the modem in addition to the far echo canceller conventionally found in modems. However, the bulk delay employed by the additional far echo canceller is arranged to be a delay of two round trips between the transmitting modem and the receiving modem rather than the conventional single round trip delay of the conventional far echo canceller.

Abstract: To improve the signal to noise ratio of the receiver of a receiving modem, the receiving modem is equipped with the ability to cancel the listener echo. Cancellation of the listener echo is achieved by coupling to the listener echo canceller of the receiving modem the phase corrected adaptive equalizer output signal, which is conventionally found in modems. The phase corrected adaptive equalizer output signal contains the in-phase, quadrature (also known as X and Y, or real and imaginary, components of the) received modem signal at the symbol rate. Advantageously, doing so results in an improved SNR for the receiver of the receiving modem, thus allowing higher data rates or reduced error rates without requiring extension of the length of the modem equalizer. When the telephone network does not introduce any frequency offset of the modem signal in the channel, the listener echo canceller may be simplified to reduce its cost.

Abstract: A method and apparatus for detecting and correcting for variations in the flat delay, which permits smooth echo canceller operation even under dynamic delay conditions. In a delay monitor, the received signal is compared against delayed versions of the echo estimate to determine whether a shift in the echo delay has occurred. If such a shift in delay has occurred then a signal indicating the amount of the shift is to the adaptive filter of the echo canceller and the filter taps are updated in accordance with the delay shift value.

Abstract: The detection of echo is enhanced using a coarse near-end speech detector at a Y-side of an echo canceler and using a more accurate near-end speech detector at the E-side of the echo canceler, such that the latter detector uses a representation of far-end speech and a threshold value to determine if the magnitude of the echo canceler output is larger than that of an echo signal only. If it is, and there is an absence of an indication of the presence of near-end speech from the coarse detector, then the more accurate speech detector adjusts the value of the threshold in a first direction, otherwise it adjusts the threshold in a second direction, to more "finely tone" such accuracy.

Abstract: The multiple contact pin holder of a modular connection device for telephone or weak current systems includes a device for solderless insulation displacement wiring which are provided with at least one pivoting cover which can be pressed down onto the body of the contact pin holder and from the contact side of which ribs extend downwards. These ribs enter the body's slits for receiving wires when the pivoting cover is pressed down onto the body and press the inserted wires into the insulation displacers of the contact pins. The slits for receiving wires are provided with lateral retaining projections arranged above one another. At least one retaining projection is located near the spot where the wires are inserted for the purpose of positioning the inserted wire, and the other retaining projection is located near a region of the insulation displacer for the purpose of fastening the wire which is pressed into the insulation displacer.

Abstract: An echo canceller is disclosed which generates an echo replica based on a transmit signal to cancel an echo. The echo canceller includes a linear echo canceller circuit for generating an echo replica of the transmit signal in the absence of distortion. The echo canceller further includes a waveform-distortion compensation circuit, coupled with the linear echo canceller circuit, for generating an echo replica for compensating waveform distortion occurred in an echo response when the transmit signal is distorted. In the echo canceller, the echo is canceled by use of the echo replica generated in the linear echo canceller circuit in the absence of distortion in the transmit signal, and is canceled by use of the echo replica generated in the waveform-distortion compensation circuit when the transmit signal is distorted.

Abstract: The device for connecting sheathed lines for telephones and data communications is characterized by a metallic ground plate with supports on a printed circuit board, etc. with one bent-back tongue which forms a contact spike for lateral insertion of a sheathed line or cable between its sheath and cover, and a second tongue located at a distance from and at least nearly parallel to the contact spike which forms a trough for supporting cables. This trough can be bent towards the contact spike by stripping the cable with a cable binder.

Abstract: A method of synthesizing an echo path in an echo canceller is provided. The method includes the steps of obtaining near end and far end signal samples at an echo canceller, locating the echo in a background task using a whitened version of the signal, transferring the echo location information to a foreground task, and eliminating the echo in the incoming signals by filtering the signal in the location passed to the foreground task by the background task.