Abstract: The present invention relates to a power supply device for a radio telephone system which can normally perform radio communication during power failure, by providing power of a battery disposed at a main body of the system or a wireless handset to the inside circuit of the main body, when direct current power is not supplied to the radio telephone system due to the power failure or the like.

Abstract: A system and method is provided for supplying power over a home phone line network in a manner that is interoperable with other voice and data services operating on the same network. The system includes a power source coupled to the home phone line network. The power source includes an AC signal generator that generates an AC signal at a selected frequency. The power source also includes a band pass filter for removing unwanted harmonics from the AC signal, thereby generating a filtered AC signal for powering one or more devices on the home phone line network. One or more devices attached to the home phone line network, such as a telephone adapter or telephone, receives the filtered AC signal. Each device comprises a second band pass filter and an AC/DC converter. The second band pass filter passes the filtered AC signal to the AC/DC converter and prevents the introduction of undesired harmonics onto the home phone line network from the AC/DC converter.

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 remote power feeding method allowing efficient remote power feeding into a network termination device in the event of a commercial power failure at a subscriber site is disclosed. When the commercial power failure occurs, a power failure signal is transmitted from the subscriber-side network termination device to the central office-side line termination device. The central office-side line termination device, when receiving the power failure signal, starts DC power feeding to the subscriber-side network termination device via the subscriber line. During the power failure, only voice communication is permitted using previously selected good channels.

Abstract: A telephone comprises an acoustic alarm, conversation members, first control means for the acoustic alarm, second control means for the conversation members, first supply means and second supply means for absorbing energy from a telephone line, the first supply means and the second supply means supplying the first control means in a call condition and the second control means in a conversation condition, respectively, wherein the first supply means further supplying the second control means in the call condition.

Abstract: Apparatuses and methods are disclosed for communications using current detection. According to one embodiment, a transmitter generates a signal on a transmission line by switching between two power sources. According to one embodiment, the transmitted signal is a balanced signal. Under an embodiment, a signal that has been transmitted on the transmission line is received by a receiver that includes a current detector, and the receiver detects the signal by sensing changes in current on the transmission line. According to one embodiment, the current detector includes a sensor that senses changes in the magnetic field generated by changes in current in the transmission line.

Abstract: A system (150) for controlling voltage supplied to a transmission line system. System (150) includes a transmission cable (134) having a characteristic impedance and a load impedance connected at its distal end. A power source (154) is connected to transmission cable (134). Power source (154) is configured to receive a voltage signal input (157) and to drive a source voltage VS based thereon. A feedback unit (155) is configured to receive the power source current (IS) as an input and further configured to generate a feedback voltage (VF) that varies with IS. A set voltage unit (152) is configured to produce a substantially constant voltage (Vset) and an adder (153) is configured to add the set voltage (Vset) to the feedback voltage to generate the voltage signal (157) that provides the input to power source (154). The feedback unit (155) may include an impedance element (156) comprising a digital signal processor or other suitable circuit that models the short circuit impedance of the transmission line.

Abstract: A network interface device (NID) for connecting a telecommunications line to a subscriber premises. The NID includes an enclosure that houses wiring, connectors, and active telecommunications devices. A cooling device, such as a fan, is used for cooling the active devices within the NID and is powered by a storage capacitor. The capacitor is charged by current from telecommunications signals on the telecommunications line using a power regulating circuit. The active devices within the NID generate heat, and the cooling device maintains a desired operating temperature within the NID. In one embodiment, the NID includes electronic components used for providing DSL service to the subscriber, and the lower frequency voice components of the telecommunications signals received at the NID are used for charging the capacitor. A microserver within the NID senses the current levels provided to the NID and to an active component module (e.g., DSL modem), and senses the electrical charge level at the storage capacitor.

Abstract: A main terminal and a method of operating the same. In this method of operating the main terminal, the main terminal is connected to a telephone network so as to communicate with the telephone network, and selectively connects an external terminal to the telephone network. To perform the method, first, if it is requested that the telephone network be disconnected from the external terminal and instead be connected to the main terminal, an internal current to flow into the main terminal is obtained from a loop voltage generated when the external terminal is in connection with the telephone network. Next, the internal current is applied to the main terminal. Thereafter, the telephone network is disconnected from the external terminal and instead connected to the main terminal. While the internal current is flowing in the main terminal, the main terminal maintains the loop voltage generated when the external terminal is in connection with the telephone network.

Abstract: A telephone line-powered power supply, a method of operating the same and telephone line-powered ancillary equipment. In one embodiment, the power supply includes: (1) a transformer having a primary winding and a secondary winding and (2) an energy storage device (which may, but is not required to, be a capacitor) series-coupled to the primary winding, the primary winding and the energy storage device adapted to be coupled to, and provide a terminating resistance for, a telephone line. A node between the primary winding and the energy storage device provides DC power. Another embodiment employs a control switch to regulate an energy storage device, thereby dispensing with a need for the transformer.

Abstract: A circuit arrangement prevents clipping of pulse metering (teletax) signals in a telephone line card channel that results from the differential impedance between a subscriber line interface circuit (SLIC) and the line at the frequency band of teletax signals. The circuit arrangement is configured to sense pulse metering signals through a delay circuit, which is coupled to a reflected signal cancellation circuit. The reflected signal cancellation circuit contains a transconductance amplifier circuit that generates a pair of complementary polarity output currents representative of the sensed teletax signal. One of these output currents is fed back to a programmed impedance element in the transmission channel path of the SLIC so as to effectively cancel the reflected teletax signal.

Abstract: A subscriber line interface circuit (SLIC) drive arrangement controllably adjusts DC biasing and overhead voltage characteristics for wireline pair that is optimized for each mode of operation of the SLIC. Respective tip and ring DC drive voltages supplied by tip and ring drive amplifiers are controlled so that the differential DC voltage across the wireline pair has a first constant value during on-hook mode, in which DC loop current may vary between zero and a first DC loop current threshold value associated with a transition from on-hook mode toward off-hook mode. During a transition between on-hook mode and off-hook mode, the tip and ring DC drive voltages are controlled so as to vary the differential DC drive voltage in proportion to monitored DC loop current. During off-hook mode, the differential DC voltage is set at a second fixed value. If an upper DC loop current threshold is reached during off-hook mode, the differential DC voltage is sharply reduced from its second constant value.

Abstract: Managing line power for network elements in an access network. In one embodiment a current sense system in a line power network is disclosed. The current sense system includes a power supply, a splitter and a sense circuit. The power supply is adapted to supply output current to a twisted pair drop. The splitter is adapted to combine communication signals and the output current on a twisted pair drop. The sense circuit is coupled to sample the output current of the power supply between the power supply and the splitter. The sense circuit is further adapted to output a sense signal that is representative of the output current.

Abstract: A method of ramping up a power supply that supplies power on a communication medium. The method includes supplying power on the communication medium with the power supply operating at a first set point, determining if an overload condition exists, and, if the overload condition does not exist, signaling a first alarm. If the overload condition exists, power is supplied on the communication medium with the power supply operating at a second set point. It is determined if the overload condition continues to exist while operating the power supply at the second set point. If the overload condition continues to exist while operating the power supply at the second set point, a second alarm is signaled.

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: The invention relates to a circuit for supplying power to a network termination unit (55) of a message transmission system, which is connected to a central station via a subscriber line (30). A local power supply voltage source (41), which is arranged in the network termination unit (55) and which supplies power during a normal operating state, is provided as well as a remote power supply source, which is arranged in the central station and which supplies power during an emergency operating state in the case of a failure or malfunctioning of the local power supply voltage source (41). The network termination unit (55) comprises a direct current converter with a transformer and a clocked switch (20). The primary winding (1) of the transformer is connected via the clocked switch (20) to the local power supply voltage source (41), and a connection of the primary winding (1) is connected via a first controllable switch (5) to a wire of the subscriber line (30).

Abstract: A line card or other telephone or communications interface provided with a ringing SLIC outputs relatively high voltage, such as in excess of about 90 volts, and/or relatively high current such as in excess of about 20 milliamps during normal use, but decreases the voltage or current of a ringing signal or other signal upon occurrence of a tip and/or ring line fault or other abnormal condition. The abnormal condition is detected by measuring voltage and/or current on the tip line and/or ring line. In response to an excess voltage or current, the ringing current or other output current is reduced to achieve desired safety and/or compliance with standards.

Abstract: A system and method that provides lifeline service to DSL customers when a loss-of-power message is sent to the central office from an integrated access device on the customer premise. If a predetermined number of loss-of-power messages are received then power is provided to the integrated access device from the central office. To this end, a power supply at the central office provides power through an isolator circuit to a relay. The relay is connected through to the twisted pair to the integrated access device. The data connection may also be powered in this manner or, in order to save further wattage, the data connection may be disconnected for the duration of the power outage.

Abstract: A method and an apparatus provide for determining whether a data terminal equipment (DTE) device represents a compatible device lacking an independent power supply and adapted to be powered using phantom power over a wired connection from a communications device such as a switch. A detection signal may be transmitted from the communications device to an identity network connected to the DTE. A response detection signal may be returned and checked in a receiver at the communications device. A switch may then be closed to provide phantom power if the result of the check indicates that the DTE is a compatible device adapted to receive phantom power. Compatible DTE device may include telephones, Voice over IP (VoIP, IP or Ethernet) telephones, network access devices, computers, and the like.

Abstract: A method and apparatus is provided for using a single power supply in a dual mode fashion. A ringing signal is received. A waveform power supply signal based upon the ringing signal. An unbalanced output buffering function upon the signal to be conditioned using an unbalanced buffering circuit. Performing the unbalanced output buffering function includes switching between a plurality of power levels of the waveform power supply signal to maintain a predetermined maximum voltage across a plurality of devices relating to the unbalanced buffering circuit.

Abstract: A method and apparatus is for providing a phantom battery feed to reduce power consumption in a differential amplifier circuit. A voltage signal is driven onto a telecommunications line using a first amplifier and a second amplifier. A phantom battery feed is performed during a negative cycle of the voltage signal. Performing the phantom battery feed comprises: supplying a negative supply terminal of the first amplifier with a supply voltage that is one-half of a full scale supply voltage; and supplying a positive supply terminal of the second amplifier with a supply voltage that is one-half of the full scale supply voltage.

Abstract: A circuit provides current from a high voltage output to a low voltage output through a resistor when a load at the low voltage output is removed. The resistor provides current to keep the VBL voltage above the set point of a switching regulator that provides output power to the VBL output. Accordingly, the regulator's output stage provides a switched 0% duty cycle output and saves power until a load is presented again. Presenting a signal to either a shutdown circuit or a sleep pin shuts down the entire controller until a load is presented again. A zener diode is used to clamp the VBL at a voltage higher than the set point of the controller to ensure that the controller operates with a 0% duty cycle output while in a no-load condition. The circuitry can be configured to operate in either a positive or negative powering scheme.

Abstract: A method and apparatus are provided for sensing current in a subscriber line. The method includes receiving a current signal from a driver capable of driving the current signal on the subscriber line, and generating a second signal in response to receiving the current signal, wherein the second signal is proportional to the current signal. The method includes receiving at least a portion of the current signal from a driver capable of sinking the portion of the current signal from the subscriber line, and generating a third signal in response to receiving at least the portion of the current signal, wherein the third signal is proportional to the portion of the current signal. The method further includes adding the second signal and the third signal to generate an output signal.

Abstract: A line powered data access arrangement (DAA) is disclosed which adaptively allows proper operation with power supplied from a telephone line as conditions warrant, while at the same time satisfying the relevant requirements of many countries. In the line powered codec, a startup procedure for the international line powered codec uses register settings, e.g., country-specific register settings, which are powered and maintained from the low voltage side (e.g., from the PC or modem side) of the line powered codec. In this way, even during low line power conditions the programmed state of the line powered codec can be maintained, thus a default condition will not necessarily returned to by the line powered codec upon reset due to a power loss in the telephone line. In another aspect, a charge storage device such as a charge capacitor is charged from a charge pump formed from a differential clock signal from the low voltage side.

Abstract: An apparatus and method for enabling Cisco legacy power to support IEEE 802.3 AF standard power. A network power system capable of delivering data terminal equipment power via a media dependent interface includes power source equipment according to Cisco legacy power and at least one powered device according to IEEE standard power. A power compatibility module is inserted between the power source equipment and the powered device to enable the power source equipment to appear according to IEEE standard power and the powered device to appear according to Cisco legacy power. The module includes switches, a DC/DC converter, an IEEE power source equipment circuit, and an isolator. The module optionally includes a user signaling device for communicating operating conditions of the module to a user. The module may be connected to two ports of the power source equipment to supply adequate power levels to the powered device.

Abstract: An apparatus for powering a plurality of devices sharing a supply line includes a supply control and a variable supply associated with the supply line. The supply control varies the supply level of the supply line to accommodate the supply level request representing a greatest magnitude supply level of any requests communicated from the devices. Another apparatus includes a plurality of supply controls each coupled to control a supply level provided by an associated supply line. Each device is capable of selectively coupling itself to an exclusive one of the supply lines. At least one device communicates a supply level request to a selected supply control that adjusts the supply level of its associated supply line to accommodate the supply level request representing the greatest supply level magnitude of any other supply level requests. If necessary, the selected device switches to the supply line associated with the selected supply control.

Abstract: A system for providing DC power on local telephone lines, such as telephone lines in a building or office, for powering devices and circuitry associated with communications over those telephone lines, as well as other functions. Desired voltage and power levels are supplied over local telephone lines by separating the DC power component from the central office or private branch exchange with a DC blocking filter while passing all AC telephony signals. A distinct DC power is then imposed over the telephone line for powering both the telephony service as well as other loads. Conventional telephone off-hook detection is simulated for compatibility with the central office or private branch exchange. The functions required may be integrated, partially or fully within a telephone outlet.

Abstract: Method and apparatus for providing a regulated and current limited power source to support bidirectional telephone delivery circuitry and methods for a multiplicity of telephone subscriber lines to a downstream distribution terminal using only two preexisting transmission lines for carrying the regulated and current limited power along with a multiplicity of HDSL TDM communication channels.

Abstract: A ‘lifeline’ POTS back-up mechanism is operative to provide emergency plain old telephone service connectivity over a span-powered two-wire metallic digital subscriber loop pair, in response to a customer's phone going off-hook, during a lack of normal operating condition of the digital circuit path. A ground fault interruption signal is generated in a remote terminal and used to activate respective POTS by-pass paths in the remote terminal and a central office terminal.

Abstract: A system and method for optimizing power dissipation in a plurality of Subscriber Line Interface Circuits (SLICs) is disclosed. In one embodiment, a first voltage source is operable to supply a first voltage to a portion of the SLICs and a second voltage source is operable to supply a second voltage to the portion of the SLICs. Data relating to subscriber loops served by the SLICs is collected and used to dynamically determine the second voltage.

Abstract: A CMOS implementation for a DC holding circuit in direct access arrangement (DAA) circuitry is disclosed that provides desirable inductive behavior while minimizing power dissipation required by the CMOS integrated circuit, particularly at high loop currents. The DC holding circuitry disclosed may include MOS transistors located on a CMOS integrated circuit and an off-chip power dissipating resistor that acts to dissipate power external to the CMOS integrated circuit. The CMOS implementation disclosed also allows a path for drawing DC current to power other CMOS circuits (e.g. ADCs and DACs) in the CMOS integrated circuit.

Abstract: A message transmission system having at least one subscriber's terminal device that is connected by way of a subscriber's line that is comprised of a first and second lead, with a subscriber's interface circuit (SLIC), preferably integrated, which comprises a loop detector circuit and subscriber's feeder circuit, such that in the area of, or on the subscriber's terminal device, a subscriber signaling display is provided, which may be controlled by way of a signaling control circuit, and such that a controllable switch (8) is connected between the subscriber's interface circuit (3) and the first lead (a) of the subscriber's line (a, b), which switch, in a first position, connects the first lead (a) of the subscriber's line (a, b) and an input of the subscriber's interface circuit (3) with each other, and in a second position, connects the first subscriber's line lead (a) with a pole of an additional power source (5).

Abstract: A communication system and method for allocating overhead voltage between a telephonic switch and a user device is described. A line driver is located in the telephonic switch and is coupled to the user device. The line driver is in one of a plurality of communication states. A processor, coupled to the line driver, allocates the overhead voltage in response to the communication state of the line driver.

Abstract: The invention provides a subscriber circuit for a public telephone set which eliminates the necessity to make a voice signal to be introduced to a channel filter a small signal. A voltage holding circuit is controlled with a polarity reversal indication signal which is supplied also to a loop current supply circuit so that a voltage detected by a line voltage detection circuit is held by the voltage holding circuit. A reversal circuit is controlled with the polarity reversal indication signal so that the polarity of the voltage held by the voltage holding circuit is reversed. The voltage of the reversed polarity is buffered by a low-pass filter having a characteristic same as that of a low-pass filter which buffers polarity reversal in the loop current supply circuit, and is then subtracted from the output of the line voltage detection circuit by a subtraction circuit.

Abstract: A CMOS implementation for a DC holding circuit in direct access arrangement (DAA) circuitry is disclosed that provides desirable inductive behavior while minimizing power dissipation required by the CMOS integrated circuit, particularly at high loop currents. The DC holding circuitry disclosed may include MOS transistors located on a CMOS integrated circuit and an off-chip power dissipating resistor that acts to dissipate power external to the CMOS integrated circuit. The CMOS implementation disclosed also allows a path for drawing DC current to power other CMOS circuits (e.g., ADCs and DACs) in the CMOS integrated circuit.

Abstract: The invention relates to a method for distributing electric power in telecommunication central office equipment intended to operate at voltages within a determined range, according to which method the voltage of the distributed power is allowed to drop temporarily below the lowest voltage of the range.

Abstract: A CODEC and a SLIC assembly perform current-sensing-voltage synthesis impedance matching and DC feed control functions. Signal processing that does not require high voltage, such as impedance matching and DC feed control, is performed in the digital domain by the CODEC while the SLIC assembly includes high voltage circuitry. This configuration is useful for Voice over Internet Protocol (VOIP) applications with a short subscriber line loop or other long loop applications. The SLIC includes high voltage operational amplifiers (op amps) to drive ring and tip signals. Bipolar transistors are also provided as bias compensating diodes for bias point stabilization over dynamic operating conditions such as temperature. The high voltage op amps include a composite MOSFET-bipolar complimentary symmetry driver stage that offers the bias control and stability of a bipolar device topology and drive capabilities of a power MOSFET device.

Abstract: A line powered data access arrangement (DAA) is disclosed which adaptively allows proper operation with power supplied from a telephone line as conditions warrant, while at the same time satisfying the relevant requirements of many countries. In the line powered codec, a startup procedure for the international line powered codec uses register settings, e.g., country-specific register settings, which are powered and maintained from the low voltage side (e.g., from the PC or modem side) of the line powered codec. In this way, even during low line power conditions the programmed state of the line powered codec can be maintained, thus a default condition will not necessarily returned to by the line powered codec upon reset due to a power loss in the telephone line. In another aspect, a charge storage device such as a charge capacitor is charged from a charge pump formed from a differential clock signal from the low voltage side.

Abstract: An interface apparatus interposed between a cordless telephone base unit and a personal computer sound card. Such interface emulates a Central Office connection with respect to the telephone and a mic and speaker connection with respect to the computer sound card. The apparatus is suitable for all cordless telephones regardless of frequency allocation standards because the interface occurs at the RJ-11 modular jack of the cordless phone base, normally intended for connection to a CO line. Differences in telephone line regulations that exist among countries are accounted for with no burden of complexity to the user of the present invention. The interface comprises active and passive circuits perform two-wire-to-four-wire conversion and signal conditioning. Local loop current may be obtained from batteries or a suitable AC power adapter.

Abstract: Multipoint interface devices (MPID) for digital subscriber line environments are provided. In one embodiment an MPID is provided for each item of customer premises equipment that is connected to the telephone line. An MPID may include a signal transform device having a particular signal transform function. For example, a low band MPID individually adapts each voice band device such as a telephone set, facsimile machine, PBX machine, or the like, to a standard telephone line. A high band MPID individually adapts high speed digital modem devices including ADSL, RADSL or HDSL to a customer's telephone line. Thus, each item of equipment is connected in parallel through an appropriate MPID to a common telephone line. In another embodiment an interface device includes selectable low-band and high-band MPIDs. In another embodiment, an MPID includes means for automatically engaging the MPID only when the affected line is in use.

Abstract: A telephone line interface circuit is disclosed having intelligent line current control that can adjust to the various requirements of worldwide telephone systems (DC masks), and/or can reduce the power consumed by the interface circuit. A controller reads a voltage value and based on the theoretical model of a telephone line network, and the expected current/voltage characteristic, as dictated by the appropriate DC mask. The controller sets the line current (via an output voltage) to an optimum value and causes the line voltage to adjust so as to comply with the DC mask and/or minimize power dissipation in the circuit.

Abstract: An image capture, conversion, compression, storage and transmission system provides a data signal representing the image in a format and protocol capable of being transmitted over any of a plurality of readily available transmission systems and received by readily available, standard equipment receiving stations. The system is adapted to be installed in a standard cellular phone configuration, providing a portable, hand held, wireless transmission system for transmitting video image signals to a remote receiving station.

Abstract: Terminals are connected via cables in a star-shaped fashion with respect to a HUB in a LAN. Each of the cables includes therein signal lines and power feed lines. The HUB includes therein a power feed section. The power feed section and the power feed lines of each cable are connected to measure a value of current which flows in the power feed lines. If it is judged based on the measured current value that the terminal connected to the corresponding cable is a telephone terminal, the power feeding to the corresponding power feed lines is continued. On the other hand, if the terminal is judged to be a terminal other than the telephone terminal, the power feeding is stopped.

Abstract: Known is a wire bound telecommunications device to be coupled to telecommunication lines comprising a transmission circuit coupled between the telecommunications lines, which transmission circuit comprises a power supply circuit for forming a supply voltage from a telecommunications line voltage, whereby the power supply circuit comprises sensing means for sensing a telecommunications line current and adjustment means for adjusting the supply voltage, a supply voltage terminal being coupled to the sensing means. In the known device, no optimal matching is obtained for the load line of the power supply to a DC-mask for line voltages as a function of a line current as prescribed for a given country. A more optimal matching is proposed.

Abstract: The stage includes two channels each connecting an input to an output. Each channel includes a first device for adding to the input voltage of the channel concerned a feedback voltage from the other channel to the channel concerned. For remote power feeding a terminal, the stage further includes respective means in each channel for adding a DC voltage to the output voltage of that channel. The feedback voltage is a function only of the AC component of the output voltage of the first device of the channel concerned. Application to telephone exchanges.

Abstract: The size and power consumption of a ring trip monitor circuit, which performs one of the BORSHT functions of a telephone line card, is reduced by utilizing an operational amplifier with feedback resistors, a resistor network, and a ring signal generator that is only connected to the line when a ring condition is present.

Abstract: A comparator-based switchmode power converter monitors the most negative of the tip and ring line voltages, to control the supply voltage to a SLIC. The voltage applied to the SLIC's power terminals is slightly higher than the sensed voltage for different loop signaling conditions, including loop start, ground start balanced ringing. The switchmode converter includes a comparator coupled to a DC-DC output node downstream of a MOSFET switch installed in a DC supply rail of a source of DC supply voltage, and coupled to a power supply terminal of the SLIC. The comparator is also coupled to a set point node, which is coupled through a voltage offset path to each of tip and ring portions of the telephone line.

Abstract: A power management circuit for use in a terminal interface device such as a modem which converts available line side power into usable power for use by the terminal interface device to activate a variety of line status indicators. These line status indicators signaling the off-hook status of the terminal interface device, low line side power, or the presence of excessive line current. The line status indicators draw power from the available line side power without placing a burden on the attached digital device or its power source. Certain line status indicators utilize flasher/oscillator circuits to increase the functionality of the line status indicators by providing a frequency based pulse to more accurately describe the operating environment of the circuit.

Abstract: An improved modem architecture and associated method are disclosed that integrate modem and line-isolation circuitry so as to achieve modem functionality and system-side isolation functionality on a single integrated circuit. The combined modem and line isolation system includes a line-side line-isolation integrated circuit which contains caller ID circuitry. The caller ID circuitry includes a caller ID analog to digital converter for processing caller ID data. The caller ID analog to digital converter may be powered by a power supply generated from power provided across a capacitive isolation barrier. The caller ID circuitry may be coupled to the ringer inputs of the line-side line-isolation integrated circuit. The ringer inputs may be capacitively coupled to the phone line.

Abstract: A method for reducing audible noise in a telephone from a splitterless asymmetric digital subscriber line modem. The modem examines the shape of the power spectrum of fast retrain signals both when the telephone is on-hook and off-hook. By comparing the spectra, in particular the slopes of the spectra, the modem may determine the quality of the telephone that shares the telephone loop with the modem. The modem cuts back its transmitted power depending on the quality of the telephone by an amount that suppresses the audible noise in the telephone. In this manner, a customer may simultaneously use the telephone and the modem on the same telephone loop.