Abstract: Attenuation circuitry for a wireless receiver system receives and attenuates an input signal. The attenuation circuitry includes an input pin, coil circuitry, capacitor network circuitry, and inverter circuitry. The input pin receives the input signal. The coil circuitry is electrically connected to the input pin, receives the input signal from the input pin, and outputs an adjusted signal from the input signal. The capacitor network circuitry is electrically connected to the coil circuitry. The capacitor network circuitry receives the adjusted signal from the coil circuitry, and outputs an attenuated signal from the adjusted signal. The inverter circuitry is electrically connected to the capacitor network circuitry. The inverter circuitry receives the attenuated signal and generates an output signal from the attenuated signal. The output signal is output from the attenuation circuitry via an output inductor.

Abstract: A method, terminal and program for processing a speech signal, in which the speech signal is received over a network from a transmitting device, wherein the frequency components in the received speech signal are limited to a predetermined frequency range and the received speech signal has been filtered using a transmitter frequency response over the predetermined frequency range. The received speech signal is decoded. The decoded speech signal is filtered using a receiver frequency response which is complementary to the transmitter frequency response over the predetermined frequency range to thereby reduce distortion in the speech signal introduced over the predetermined frequency range by using said transmitter frequency response.

Abstract: An induced loss value is retrieved from a configuration file of an MTA device. The loss value is provided to a signal generator that generates call progress/alerting signals and FSK signals in the MTA telephony device. To mitigate the imbalance between incoming voice signal levels and call progress/alerting signals that may occur because the call progress/alerting signals are not generated at a level equal to that of the incoming voice signals, the loss/attenuation amount from the configuration file is used to adjust the levels of the generated call progress/alerting and FSK signals by a corresponding amount before they are attenuated along with the incoming voice signals.

Abstract: A system and method for processing a communication signal from a wireline is provided. The system comprises a coupling unit and signal processing circuitry. The coupling unit comprises a transformer and is configured to receive the communication signal from the wireline. The coupling unit is also configured to generate a first signal based on amplifying or attenuating the communication signal according to a first winding ratio of the transformer and a second signal based on amplifying or attenuating the communication signal according to a second winding ratio of the transformer. The signal processing circuitry is configured to process the first signal and the second signal.

Abstract: A method of generating a plurality of supply voltages for a plurality of subscriber line channels includes generating a first target VBAT value for a first associated linefeed driver from a first VBAT control. A second target VBAT value for a second associated linefeed driver is generated from a second VBAT control. A selected target VBAT value is generated based upon the first and second target VBAT values. A magnitude of the selected target VBAT value is not less than any maximum of a magnitude of the first and second target VBAT values. A switching regulator is controlled to provide a first generated VBAT corresponding to the selected target VBAT value, wherein the switching regulator provides a second generated VBAT having a pre-determined proportional relationship (p) to the first generated VBAT.

Abstract: A method for scheduling ringing signals for a plurality of subscriber lines includes maintaining a schedule of ringing signals for the plurality of subscriber lines. A plurality of ringing counts is determined. Each ringing count specifies a number of subscriber lines ringing at a selected point in the schedule. A ringing request for a particular subscriber line is received. A position in the schedule for the ringing request is identified based on the ringing counts that does not exceed a maximum ringing limit. The ringing request is scheduled in the schedule responsive to identifying the position. A ringing signal is generated for the particular subscriber line in accordance with the schedule.

Abstract: A system and method for processing a communication signal from a wireline is provided. The system comprises a coupling unit and signal processing circuitry. The coupling unit comprises at least one transformer and is configured to receive the communication signal from the wireline. The coupling unit is also configured to generate a first signal based on amplifying the communication signal according to a first winding ratio of the at least one transformer and a second signal based on attenuating the communication signal according to a second winding ratio of the transformer. The signal processing circuitry is configured to process the first signal and the second signal. The wireline is optionally a powerline.

Abstract: A method, a device and a system for Upstream Power Back-Off (UPBO) in a Digital Subscriber Line (DSL) are provided. The method includes: collecting subscriber line information (S50); determining a reference line length according to the subscriber line information (S52); obtaining UPBO parameters of each upstream band of each subscriber line according to the determined reference line length (S54), where the UPBO parameters include an original point parameter, a back-off slope parameter, and a maximal close frequency point (UPBOFMAX) corresponding to the band; and executing an UPBO process on the band of the corresponding subscriber line below the UPBOFMAX according to the UPBO parameters (S58). Thus, the stability of longer lines can be ensured, an upstream rate of short lines is maximally increased, and the existing UPBO mode is fully compatible.

Abstract: A hybrid circuit for a full-duplex transceiver includes a two-to-four wire ratio converter (50, Z1, Z2) for forwarding a transmitted signal TX? on a transmission line (41) in response to an input signal TX. The ratio converter also produces a signal RXA in response to a received signal RX arriving on the transmission line, wherein signal RXA includes an echo of input signal TX. A passive filter (H1) and a first active filter (H2) each filter input signal TX to generate signals TXA and TXB summed with the RXA signal to form a signal RXB at the input of an amplifier (52, Z3, Z4) producing an output signal RXC. A second active filter (H3) filters input signal TX to generate a signal TXC summed with the RXC signal to produce the output signal RX. The impedance of the passive filter is designed so that when the transmission line has a target impedance, such as the impedance of an ideal twisted pair, the TXA output signal of the passive filter adequately offsets the TX signal echo in RXA.

Abstract: A system for controlling transceivers based on a location of the transceivers, as indicated by a location indicator, helps to reduce crosstalk interference in signals transmitted from central offices. The system utilizes a location indicator and logic. The location indicator is communicatively coupled to each of a plurality of transceivers and is indicative of whether the plurality of transceivers are located at an intermediate terminal or a central office. The logic is configured to control a physical layer of each of the transceivers based on the location indicator.

Abstract: An Inter-modulation distortion measurement and correction method which could be applied over a communication channel that is a combination of either or both analog and digital channels. This method is applicable for a communication system between a modem pair.

Abstract: A power offload network has a node for receiving at least one supply V1. The power offload network includes at least one switch and a power offload element providing a supply drop of VR. The switch is configurable for selecting a linefeed supply level from the set including {V1, V1?VR}. A subscriber line interface circuit receives the selected linefeed supply level for driving a subscriber line.

Abstract: Method and apparatus for transmitting a transmission signal via a two-core line, in particular a telephone line, in which case, with the aid of corresponding transmission devices (2, 3), two partial signals are generated and are transmitted via a respective core (A, B) of the line and the transmission signal is formed by the alternating-current difference between the two partial signals. In order to suppress common-mode components in the partial signals, a calibration is carried out in such a way that the transmission devices (2, 3) output essentially the same output level.

Abstract: Methods and apparatus for protecting quality of service during a process involving bridge tap in a communications system are described. Bridge tap may occur during system construction, central office re-concentration, replacement projects, upgrade projects, expansion projects, and installation of back-up cables, etc. Cables, with one end connected to a point in the system, and the other end left unterminated, result in bridge tap. In the bridge tap moderator of the present invention, a plurality of termination networks are attached to a modular connector such that a separate termination load is placed across each connector terminal pair for each corresponding wire pair of the cable. Communication lines can be easily attached to the moderator thereby easily, quickly, and efficiently eliminating bridge tap on a large number of wire pairs. The bridge tap modulator apparatus and method of use also minimize the amount of time bridge tap exists during cable and/or communication device installation.

Abstract: Before any supply of remote power to a telecommunications terminal connected to a local area network, the Ethernet equipment must recognize the power class of the terminal by measuring a specific electrical signature of the terminal via their interconnection. If the Ethernet equipment is unable to supply the required power, then it will send a specific signal via the interconnection which will activate an alarm on the terminal. The possibility to be alerted by a specific alarm from the terminal if no remote power can be supplied to it, will advantageously inform the terminal user of the problem and allow the user to look for an alternative.

Abstract: A technique for implementing impedance matching circuits 100 that use the transfer functions of each line impedance model. This technique allows implementation of an impedance match for a diverse number of line impedances reusing the same circuit 100 topology, by simply adjusting coefficients to accommodate different line impedances.

Abstract: A telephone system includes a transmission line for connection to at least one telephone and a telephone interface in communication with the transmission line. The telephone interface provides DC power when a telephone connected to the transmission line is in an off-hook state. A controller in communication with the telephone interface generates a pre-defined DC characteristic of the telephone interface, and a regulator in communication with the controller adaptively translates the DC characteristic.

Abstract: An apparatus, system and method for providing variable attenuation to data signals in an xDSL frequency range are disclosed. An attenuation device has a resistive circuit coupled to a capacitive circuit that prevents telephone signals from being attenuated by the resistive circuit and allows normal operation of telephone services at a subscriber premises.

Abstract: Disclosed is a method and apparatus which facilitates the use of existing power that is ordinarily unused or discarded to provide power to a telephone interface circuit when the circuit is in the on-hook state, thereby alleviating the need to use loop current to power the interface during the on-hook state. Existing clock signals are used to charge capacitors that are normally used for capacitive coupling of digital data across the high voltage isolation barrier. Although only small-value capacitors are needed for transmitting data across the capacitive interface, larger-value capacitors are used and are configured to form a charge pump to generate power to the interface at all times. Thus the interface always has a steady source of power available for use, including during the on-hook state for powering circuitry that can detect, modulate, and transmit on-hook signals across the capacitive interface.

Abstract: The asymmetric digital subscriber line receive channel includes: first and second external resistors 20 and 22 coupled to a telephone line 24 and 26; a coarse programmable gain amplifier CPGA formed in a low voltage process having inputs coupled to the first and second external resistors 20 and 22; and a fine programmable gain amplifier PGA1 coupled to an output of the coarse programmable gain amplifier CPGA, and having a very fine gain trim adjustment to compensate for a mismatch between the external resistors 20 and 22 and the coarse programmable gain amplifier CPGA.

Abstract: A line circuit utilizing a differential amplifier whose output is regulated to zero volts D.C. (when the subscriber's set is off-hook) by a negative feedback circuit, for controlling a voltage controlled power supply which provides a constant current feed to the subscriber's loop. The differential amplifier also transmits audio signals received from the subscriber's loop directly to a PABX via an unbalanced terminal. When the loop range exceeds a predetermined threshold, the circuit reverts to a voltage feed operation thereby allowing operation over long loop lengths and the ability to provide on-hook CLASS services.

Abstract: A feed arrangement for a telephone subscriber loop. The feed arrangement includes an input for connection to a power supply and an output for connection to the TIP and RING conductors of the subscriber loop. A control element regulates the current in the subscriber loop to a target value selected in a set of possible target values. When the control element senses that an additional telephone instrument becomes active in the subscriber loop, a new target value is selected. The new target value is such that the current is sufficient to power all the telephone instruments that are currently active in the subscriber loop while low enough to avoid an excessive power dissipation at the feed arrangement and also to limit the power consumption.

Abstract: A digital direct access arrangement (DAA) circuitry may be used to terminate the telephone connections at the user's end to provide a communication path for signals to and from the phone lines. Briefly described, a means for providing a proper hookswitch transition for a variety of international phone standards is provided. The invention may also be utilized with means for transmitting and receiving a signal across a capacitive isolation barrier. More particularly, a DAA circuitry may be utilized which satisfies many or all hookswitch transition standards without the use of additional discrete devices. The hookswitch transition standards may be satisfied by ramping down the current flowing through the hookswitch prior to transitioning the hookswitch state. In this manner the hookswitch current change as a function of time (di/dt) may be decreased. Thus, the current through the hookswitch may be actively controlled prior to switching the hookswitch from an off-hook condition to an on-hook condition.

Abstract: A subscriber line driver (SLD) is provided for the continuous and automatic transformation of the characteristics of a communication system signal so that the signal conforms to a power spectral distribution (PSD) standard. The signal is transformed by the SLD which may increase (amplify) portions of the signal to a predefined specification, decrease (attenuate) portions of the signal to a predefined specification, and/or frequency modulate or filter the transmit signal frequencies to fit within the communication channel frequency bandwidth as defined by a predefined frequency band. After modification by the SLD, the transformed communication signal is injected (transmitted) into a communication transmission line. An SLD device can be employed in a variety of communication systems such as a public telephony system, a private branch exchange (PBX), a coaxial cable system, a fiber optic system, a microwave system, a radio communication system or the like.

Abstract: A system and method of communicating between a central office and a plurality of subscriber sites. Subscriber sites are separated into frequency groups. Each group spans a distance along the cable such that no more than a predetermined amount of attenuation is required to equalize the signal power of signals sent from a site in the group. Frequency groups closer to the central office are assigned higher frequency bands than frequency groups farther away from the central office. The central office includes a plurality of filters, each of which has a passband for passing the frequency band of a group and a stop band that substantially attenuates the frequencies of the other groups. The frequency group nearest the central office has no filter. The passband of a filter may also provide any needed attenuation to assure that signals arriving at the central office have approximately the same power levels.

Abstract: The current invention provides a method and apparatus for wireline characterization is disclosed. The method may be implemented with any modulation protocol but is particularly suited for multi-carrier modulation protocols such as discrete multi-tone (DMT). The apparatus may be incorporated into physical or logical modems. In an embodiment of the invention an apparatus for wireline characterization in a modem with a transmit path and a receive path each configured to couple with a remote modem via a wireline in which available communication bandwidth is split into a number of independent sub-channels is disclosed. The apparatus comprises: a tone selector, a cumulative loss estimator and a shift register. The tone selector selects a subset of the number of sub-channels within the bandwidth of a received wireline communication for which subset the sum of the square roots of the corresponding sub-channel indices may be expressed as an integer power “n” of 2.

Abstract: A system comprising a base unit and a remote unit for transmitting telephonic data on AC power lines is disclosed. The base unit includes a transmitter section, a receiver section, a power line interface, a telephone line interface, a power supply, and a first microcontroller. The telephone line interface is coupled to a telephone line to apply the telephonic data signals to and receive signals from the telephone line. The telephone line interface has a ring detector, a muting circuit, and a hook switch. The transmitter is coupled to the telephone line interface and the power line interface. The transmitter has a modulator, an oscillator, an amplifier, and a filter. The receiver is coupled the telephone interface and the power line interface. The receiver has a filter, an amplifier, and a detector. The remote unit includes a transmitter section, a receiver section, a power line interface, a telephone interface, a power supply, and a second microcontroller.

Abstract: A holster (10) for a telecommunication device (12), such as a cellular telephone or wireless telephone, includes a housing (14) adapted to removably support the telecommunication device (12). The holster (10) also includes an earpiece assembly (52) including at least one transducer, such as an earbud (53) or a microphone (54), and a cord (56) depending from the at least one transducer (53, 54). The earpiece assembly (52) is extendable and retractable relative to the housing (14). The holster (10) further includes an extension/retraction assembly (32) having a spool (34) for taking up at least a portion of the cord (56) when the earpiece assembly (52) is retracted relative to the housing (14), and at least one coil spring (35) adapted to rotate the spool (34). The at least one coil spring (35) can electrically couple the at least one transducer (53, 54) to the telecommunication device (12).

Abstract: A speech processor uses at least two speech processing features to enhance the quality of speech signals received by a user during a telephone call. The speech processing features are applied to the speech signals. However, the user only hears speech signals affected by one speech processing feature until both features have fully converged or ramped-up, and the two features are no longer interfering with each other. At that point, a “flash-cut” of the second speech processing feature is activated. The flash-cut instantaneously switches to speech signals affected by both features. This quick transition makes the speech processing features more noticeable to the user, and the user is not subjected to the period where the features interfere. Further, an optional audio indicator is generated before implementing the flash-cut, so the user is alerted to the flash-cut, and the speech processing features are even more noticeable.

Abstract: A dual-supply line-interface circuit (100) uses a −48V power supply (VBAT1) to drive long subscriber loops (120) and uses a −28V power supply (VBAT2) to drive short subscriber loops. For intermediate-length loops, a dual-slope current-feed profile (FIG. 4) is employed to limit the line-circuit's power dissipation. The line-interface circuit operates in an apparent constant-current mode, generating about 40 mA of differential line current using the low power supply, up to a threshold line voltage of about 25V, which is equal to the low power supply voltage minus required overhead. For longer loops, the line-interface circuit switches to a second constant-current mode, generating about 22 mA of differential current using the high power supply, which maintains the loop current constant until it drops to the 48V resistive-feed value.

Abstract: A control processor is connected to a subscriber line interface circuit to control the operating mode of the line interface circuit and monitor, via a detector output terminal of the line interface circuit, the status of the line connected to the line interface circuit. The control processor is adapted to control the line interface circuit to ensure, at a first point of time, that its detector output terminal is in a first signal state and, at that first point of time, to initiate a measurement of the line voltage. The line interface circuit is adapted, at a second point of time, to bring the detector output terminal to a second signal state after a time interval whose length in a predetermined manner is proportional to the measured line voltage, and the control processor is adapted to convert the time interval during which the detector output terminal of the line interface circuit is in the first signal state to a voltage value corresponding to the line voltage.

Abstract: Apparatus for remotely powering access equipment over a 10/100 switched Ethernet network comprises an Ethernet switch card with a phantom power supply for remote access equipment and added circuitry for automatic detection of remote equipment being connected to the network; determining whether the remote equipment is capable of accepting remote power in a non-intrusive manner; delivering the phantom power to the remote equipment over the same wire pairs that deliver the data signals, and automatically detecting if the remote equipment is removed from the network.

Abstract: In a subscriber line interface circuit connected to a telephone line having a high potential wire and a low potential wire, an arrangement for generating a signal for determining the line voltage comprises means (7, 10, 11) for alternately charging a capacitor (6), by means of a first DC current, to a first voltage, and discharging the capacitor (6), by means of a second DC current, to a second voltage. Hereby, a sawtooth wave having an amplitude corresponding to the difference between the first and second voltages is produced. This sawtooth wave is converted to a pulse train related to the line voltage, from which the line voltage can be determined.

Abstract: An Acoustic Echo Control (AEC) device operates to reduce acoustic echo feedback in a speakerphone. An adaptive echo canceller responds to a far-end speech signal to generate an estimated echo which is subtracted from a near-end speech signal, to generate a compensated near-end speech signal. An Echo Return Loss (ERL) estimator provides an accurate but gradually adjusted estimate of the ERL of the echo canceller. A non-linear processor responds to the ERL estimation and provides additional attenuation to maintain the overall system ERL. The AEC device also incorporates dual talking mode detectors, one for the adaptive filter and one for the non-linear processor, to detect a plurality of talking modes, which are used to control the adaptation of the adaptive filter and the attenuation provided by the non-linear processor.

Abstract: A speech processor uses at least two speech processing features to enhance the quality of speech signals received by a user during a telephone call. The speech processing features are applied to the speech signals. However, the user only hears speech signals affected by one speech processing feature until both features have fully converged or ramped-up, and the two features are no longer interfering with each other. At that point, a "flash-cut" of the second speech processing feature is activated. The flash-cut instantaneously switches to speech signals affected by both features. This quick transition makes the speech processing features more noticeable to the user, and the user is not subjected to the period where the features interfere. Further, an optional audio indicator is generated before implementing the flash-cut, so the user is alerted to the flash-cut, and the speech processing features are even more noticeable.

Abstract: A system (130) for providing enhancement to a voice-band signal in a telecommunications network (138) is provided. The present system (130) includes a power averager (18) for determining the average power of the voice-band signal. The present system (130) also includes an equalizer (132) for attenuating a predetermined portion of the voice-band signal and an output scaler (134) for scaling the equalized voice-band signal with a scaling factor. The system (130) of the present invention also includes an automatic gain enhancer (136) for applying an automatic gain factor to the scaled voice-band signal and wherein the automatic gain factor is dependent upon the average power of the input voice-band signal.

Abstract: An apparatus compensates for an attenuation of a signal on a telephone line in a communication system connected to the telephone line via a transformer. A photo coupler detects a loop current at a primary winding of the transformer. A controller generates switching control signals corresponding to an output of the photo coupler based on a predetermined switching table, and controls an overall operation of the communication system by receiving coding data. A level amplifier having different gains amplifies a signal at a secondary winding of the transformer by the gain corresponding to the switching control signal. A coder codes an output from the level amplifier to generate the coding data.

Abstract: A circuit arrangement for generating charge pulses during digital telecommunications is indicated, whereby subscribers (Tln) of a telephone network are connected by cables with an exchange. The subscriber telephones are connected by electric service lines to an interface unit that is connected to the exchange. The interface unit has a digital interface on the exchange side and at least one analog interface on the subscriber side. A generating circuit (3) is located in the interface unit and produces charge pulses as a function of signals transmitted by the exchange, the charge pulses being transmitted to the respective subscriber (Tln). When loop current flows through the electric circuit of each subscriber (Tln) telephone, the interface unit measures an input voltage that is proportional to the length of the service line. The thus gained voltage value is used to adjust the voltage level of the charge pulses produced by the generating circuit (3).

Abstract: A method for reducing frequency-related power losses in a telecommunication line interface circuit comprises operating a switching converter circuit at an optimum frequency. Determination of the optimum frequency is based upon a subscriber loop length. Particularly, the subscriber loop voltage is detected at a battery feed circuit of the line interface circuit, and used to access an optimum frequency stored in an initialized database. The optimum frequency information is received in the switching converter circuit, and determines its operating frequency.

Abstract: A switching device for a telecommunications channel. The device comprises a voltage detector, a switch, and a storage device. The voltage detector produces an output voltage if the voltage between the lines of the channel exceeds a predetermined level, for example 110 volts. The switch can increase an impedance in one of the lines (preferably causing open circuit) in response to an input voltage. The first storage device, for example a capacitor, produces the input voltage when it reaches a charge V.sub.2 ; is initially at a voltage V.sub.1, for example zero, that is less than V.sub.2 ; after charging by the output voltage from the voltage detector, is at a voltage V.sub.3 greater than V.sub.2 ; and discharges from V.sub.3 to V.sub.1 in the absence of the output voltage. The voltage detector comprising a low-pass filter such that an AC signal on the channel produces an output voltage that charges the first storage device to a charge below V.sub.2.

Abstract: In a communications system containing signal enhancement circuitry capable of selectively enhancing portions of a plurality of signals carried on a corresponding plurality of channels through the signal enhancement circuitry, a system and method for controlling enhancement on a per call basis. The system includes: (1) command generation circuitry for generating an enhancement command for transmission to the signal enhancement circuitry and (2) command reception circuitry, associated with the signal enhancement circuitry, for receiving the enhancement command from the command generation circuitry and selectively enhancing the portion of the signals on the per call basis according to the enhancement command.

Abstract: An automatic line equalizer for use with a T1 or an E1 repeater in a telecommunications system is disclosed. The equalizer includes a first equalizing means for equalizing an input line having a line length falling within a first range and a second equalizing means for equalizing an input line having a line length falling within a second range. The equalizer includes a line condition/length detector. The equalizer includes switch means for selectively coupling one of the first and second equalizers to the selected input line as a function of a line condition indication. The switching means prevents hunting between said first and said second equalizers.

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 twisted-pair telephone line is connected to a conventional telephone via a low-pass filter and equipment for receiving signals in an upper frequency range, e.g., 25-1000 kHz via a high-pass filter. The low-pass filter is primarily passive (to allow passage of line power, ringing and signalling voltages) but, to improve matching to non-resistive line and telephone impedances, at least the main part of the filter is flanked by impedance convertors in which amplifiers having an appropriate transfer function feed voltages back into the line via transformers through which power, ringing and dialing may pass unimpeded.

Abstract: In methods and apparatus for estimating the frequency response of telecommunications channels, signals carried on the channels are divided into pluralities of signal segments of limited duration, unvoiced signal segments are identified, and spectral components of the unvoiced signal segments are measured. The measured spectral components may be integrated over time to derive time-averaged measurements of the spectral components. The time-averaged measurements may be compared to corresponding components of expected unvoiced signal spectra to improve the accuracy of the frequency response estimates. Filters may be inserted in the channels to adjust the frequency responses, the filters having filter characteristics selected in response to the measured spectral components. The methods and apparatus can be used to compensate for poor bass frequency response in voice channels.

Abstract: A circuitry is disclosed for superimposing small, low energy (2) and large substantially higher energy (3) signals, in particular for transmitting speech signals with a remote supply direct signal for a receiving circuit or with a high energy alternating signal, for example a call alternating voltage for signaling. The circuitry includes an operational amplifier (1), having one input connected to a pole of a source supplying the small signal and operational voltage inputs being connected to a voltage supply source. In order to allow low energy, weak signals, such as speech signals, and high energy signals and direct voltages to be transmitted by such a circuitry over a subscriber line by means of simple components, the second pole of the small signal source (2) is connected to the second input of the operational amplifier (1) and one pole of a higher energy signal supply source (3) is connected to one pole of the voltage supply source (V).

Abstract: The terminating impedance can be set electrically to eliminate selection and installation of discrete components in order to meet network manager specifications. A control device such as an EEPROM is easily adjusted (programmed) to control circuits presenting a predetermined specified impedance to the communications line. The impedance is preferably formed by a switched capacitor filter in which ratios of capacitance rather than absolute values are easily obtained during manufacture of an IC. The DC termination value may be set separately from the AC impedance.

Abstract: A telecommunications network (120) is provided with adaptive gain control (AGC) of the voice signals in network (120). Network (120) includes an input (12) for receiving a voice signal, an output (14) for receiving the voice signal, and a coupling between input (12) and output (14) including at least one switch (124) or (126). Network (120) also includes voice enhancer (10) including power averager (18) for measuring and determining the average power of an input signal. Voice enhancer (10) also includes bass band equalizer (16) to attenuate a predetermined portion of the input signal to provide an equalized input signal. From the average power of the input signal is determined a scaling factor from a gain/attenuation look-up table (28). Voice enhancer (10) also includes output scaler (30) coupled to output (14), output scaler (30) scales the equalized input signal with the scaling factor and provides the scaled signal to output (14).

Abstract: A telephone line power utility circuit, in which direct-current power supplied through a telephone line-side is utilized as a power source for a line terminal device having a direct-current resistance, the telephone line power utility circuit including a DC-DC converter connected with the line terminal device for supplying the direct-current power to the line terminal device, the DC-DC converter having an input direct-current resistance; and a central processing unit (CPU), connected with the DC-DC converter, for obtaining a maximum input direct-current resistance of the DC-DC converter to increase the efficiency of receiving power of the DC-DC converter by allowing the direct-current resistance of the line terminal device, viewed from the telephone line-side, to satisfy a predetermined standard, controlling the duty ratio of the primary side switching element, and/or switching the taps of the primary side winding of the transformer of the DC-DC converter, such that the direct-current power supplied through t

Abstract: A line circuit utilizing a differential amplifier whose output is regulated to zero volts D.C. (when the subscriber's set is off-hook) by a negative feedback circuit, for controlling a voltage controlled power supply which provides a constant current feed to the subscriber's loop. The differential amplifier also transmits audio signals received from the subscriber's loop directly to a PABX via an unbalanced terminal. When the loop range exceeds a predetermined threshold, the circuit reverts to a voltage feed operation thereby allowing operation over long loop lengths and the ability to provide on-hook CLASS services.