Abstract: A termination device for a telephone line of a wire based telephone system, said termination device (30) comprising: a high pass filter (39) for separating signals within a frequency band used by a high-speed modem (13) for data transmission; and impedance means (53) connected to the high-pass filter (39), wherein said impedance means (53) has an impedance which matches the impedance of the telephone line in the frequency band used by the high-speed modem (13).

Abstract: An Internet Protocol (IP) telephone has a constant impedance filter that is capable of being continuously attached to the physical layer of a computer chip in the IP telephone. The constant impedance filter is located outside the physical layer and is connected to a relay on the physical layer. The relay is configured using native FET devices, which are normally conductive without a supply voltage. Therefore, the relay is capable of operating during the discovery mode of IP telephone operation, where no power is applied to the substrate. Rectifier circuits rectify an incoming signal during discovery mode, and apply the rectified signal to the gate of the relay to improve conductivity of the relay. This allows for faster detection of the IP telephone during discovery mode. During normal operation mode, voltage is applied to the physical layer, and the relay is opened by grounding the native devices.

Abstract: The present invention provides termination for transmission line structures propagating common mode signals. Common mode signals typically represent noise in systems wherein information is transmitted as differential mode signals. The present invention terminates the common mode signals in a dynamically matched termination that prevents or significantly reduces reflection of said common signals without interference with differential mode transmission lines or their normal operation. Application is shown for an unshielded, twisted pair transmission line as commonly used in telephony-based systems for both voice and broadband data communication. The methods for application of the present invention to systems with large numbers of conductors are also shown.

Abstract: The invention provides a transmission apparatus (100) for transmission of electrical signals between a line driver (205), which is connected to a transmission line (201), and a switching center (301), having an analog feedback device (101) for coarse setting of a line voltage level (210) on the transmission line (201), and a digital feedback device (102), which is coupled to the analog feedback device (101) and has a feedback filter device (118), designed such that a filter input signal (404) can be converted to a filter output signal (405) at a rate which is lower than the sampling rate (fa) of an analog/digital converter (104).

Abstract: A method includes generating an output signal at a transmitter using an input signal. The method also includes providing the output signal for communication over a communication link. The method further includes identifying a return signal by at least partially removing from the output signal at least one of: the communicated signal and base line wander. In addition, the method includes establishing a synthesized impedance to the return signal.

Abstract: A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral.

Abstract: The present invention provides termination for transmission line structures propagating common mode signals. Common mode signals typically represent noise in systems wherein information is transmitted as differential mode signals. The present invention terminates the common mode signals in a dynamically matched termination that prevents or significantly reduces reflection of said common signals without interference with differential mode transmission lines or their normal operation. Application is shown for an unshielded, twisted pair transmission line as commonly used in telephony-based systems for both voice and broadband data communication. The methods for application of the present invention to systems with large numbers of conductors are also shown.

Abstract: A high-speed bit stream interface module interfaces a high-speed communication media to a communication Application Specific Integrated Circuit (ASIC) via a Printed Circuit Board (PCB). The high-speed bit stream interface includes a line side interface, a board side interface, and a signal conditioning circuit. The signal conditioning circuit services each of an RX path and a TX path and includes a limiting amplifier and a clock and data recovery circuit. The signal conditioning circuit may also include an equalizer and/or an output pre-emphasis circuit. The clock and data recovery circuit has an adjustable Phase Locked Loop (PLL) bandwidth that is set to correspond to a jitter bandwidth of a serviced high-speed bit stream.

Abstract: A high-speed bit stream interface module interfaces a high-speed communication media to a communication Application Specific Integrated Circuit (ASIC) via a Printed Circuit Board (PCB). The high-speed bit stream interface includes a line side interface, a board side interface, and a signal conditioning circuit. The signal conditioning circuit services each of an RX path and a TX path and includes a limiting amplifier and a clock and data recovery circuit. The signal conditioning circuit may also include an equalizer and/or an output pre-emphasis circuit. The limiting amplifier applies respective gains to the RX path and to the TX path that are based upon respective dynamic ranges of the incoming signals.

Abstract: Programmable plain old telephone line impedance matching circuits that provide an accurate, integrated programmable termination and source impedance for a telephone line interface circuit (SLIC). The accurate matching of this programmable termination and source impedance with the termination impedance of the 2 Wire connection eliminates signal reflections on this connection and therefore removes the echo, which echo can lead to reduced signal quality in packetized VOIP systems. The programmable integrated impedance matching circuits of this invention use a programmable time continuous amplifier preferably in combination with a double sampling programmable switched capacitor feedback stage (sampling twice per clock cycle by sampling on the positive and negative phases of a non-overlapping clock cycle).

Abstract: The invention relates to a method and a circuit for adapting the impedance in a telecommunication connection comprising a speech path and a data path having modems. Conductive properties measured by the modems are used to precisely adjust the impedance on the speech path.

Abstract: A method and apparatus is provided for performing an active impedance feedback. A signal is received. An active feedback synthesis is performed based upon the signal. Performing the active feedback synthesis includes using an active feedback network for conditioning an output signal and performing a signal summation of at least two components of the conditioned output signal for feedback.

Abstract: A digital communication system for transmitting and receiving Digital Visual Interface (DVI) communication data signals and Display Data Channel (DDC) communication signals over a transmission line comprises an open-loop equalizer circuit and a DDC extension circuit. The open-loop equalizer circuit is operable to receive DVI communication signals transmitted over the transmission line and output equalized DVI communication data signals. The DDC extension circuit is operable to inject a boost current at the receive end of the transmission line during a positive transition in the DDC communication signal, and clamp the receive end of the transmission line during a negative transition of the DDC communication signal.

Abstract: A subscriber line interface circuit apparatus includes an impedance bridge coupled to a subscriber line. A first pair of current drivers is coupled to the impedance bridge for driving a voice signal in a first frequency range onto the subscriber line. A second pair of current drivers is coupled to the impedance bridge for driving a data signal in a second frequency range onto the subscriber line. The impedance bridge couples the second pair of current drivers to the subscriber line across an output impedance of Z1+Z2 within the second frequency range.

Abstract: A method of selecting an optimum impedance for a loop start trunk line, comprising successively applying respective ones of a plurality of impedance settings to the loop start trunk line, for each impedance setting measuring the impulse response of the trans-hybrid echo path by applying audio test signals to obtain a time-domain trans-hybrid transfer function and deriving a frequency-domain spectrum representative of trans-hybrid loss, and then calculating figure of merit of the transfer function based on the power spectrum. Once all impedance settings have been tested, the optimum impedance is selected as the impedance setting associated with the highest calculated figure of merit.

Abstract: A passive echo cancellation circuit for reducing echoes on a subscriber line includes an output driver adapted to drive a downstream signal on the subscriber line. First sensing circuitry is coupled to the output driver and adapted to sense a current on the subscriber line to generate a first voltage. A balancing network is adapted to receive at least a portion of the downstream signal. Second sensing circuitry is adapted to sense a current in the portion of the downstream signal passing through the balancing network to generate a second voltage. An upstream driver is adapted to subtract the second voltage from the first voltage to generate an upstream signal.

Abstract: A line interface performs echo cancellation without the use of a hybrid filter network and includes a transmit path having a line driver, a single matching network terminating the line, and a single transformer. The transformer uses split windings on both the primary side and the secondary (line) side. Each half of the primary side is tapped to obtain a turns ratio of N1:N2, while each half of the secondary side of the transformer has N windings. The single matching impedance is coupled in parallel between the first winding and the second winding on each half of the primary side. Either the voltage across the matching impedance or the voltage across the receive terminals is bootstrapped to the receive signal through multiple negative feedbacks. The transfer function of the line driver is shaped as a first-order high-pass filter (HPF) to reject any out-of-band noise and distortion components.

Abstract: An apparatus for controlling operation of a recording device with a telephone configured for orientation in a first state and a second state includes: (a) an information conveying section for conveying information from the telephone to a recording locus in the recording device; (b) an indicating section for receiving a monitor signal having a first value when the telephone is in the first state and having a second value when the telephone is in the second state; the indicating section employs a single fixed bias to generate a first indicating signal when the telephone is in the first state and to generate a second indicating signal when the telephone is in the second state; and (c) an engaging section; the engaging section responds to the first and second indicating signals to orient the recording device for recording the information or for not recording.

Abstract: The present invention relates to a regulator for impedance balancing of first (104) and second wires (106) of a transmission wire pair having respective first and second impedances, the regular comprising: means (108) for determining a first signal (116) being representative of an average of square value of a first current (i1) flowing through the first wire, means (118) for determining a second signal (126) being representative of the average of square value of a second current (i2) flowing through the second wire, means (128, 130) for determining first and second coefficients (k1, k2) on the basis of the first and second signals, first feedback means (132, 134, 136) for regulating the first current on the basis of the first coefficient, second feedback means (138, 140, 142) for regulating the second current on the basis of the second coefficient.

Abstract: Subscriber line interface circuitry includes an integrated circuit having sense inputs for a sensed tip signal and a sensed ring signal of a subscriber loop. The integrated circuit generates a subscriber loop linefeed driver control signal in response to the sensed signals. The linefeed driver does not reside with the integrated circuit. In one embodiment, the linefeed driver includes power circuitry for providing battery feed to the ring and tip nodes of the subscriber loop in accordance with the linefeed control signal. The linefeed driver includes sense circuitry providing a sensed tip signal and a sensed ring signal. The sensed tip and ring signals correspond to a tip current and a ring current of the subscriber loop. In one embodiment, the integrated circuit is a complementary metal oxide semiconductor (CMOS) integrated circuit. In one embodiment, the linefeed driver comprises only discrete components.

Abstract: Methods for matching adaptive hybrids (15) to lines (16) for making reflectograms of the lines (16) measure (1) input impedances (Zmeas) of the lines (16), model (2) characteristic impedances of the lines (16) via physical models (Zphymod), estimate (3) parameters of the physical models (Zphymod) via cost functions which depend on the measured input impedances (Zmeas), convert (30) the modelled characteristic impedances into impedance values (13), and set (31) the adaptive hybrids (15) with the impedance values (13). Unwanted near-end reflections are minimised and wanted reflections can be measured. The physical models depend on frequencies s, Bessel functions Ji and parameters ai related to geometrical dimensions A, D and L and material constants ?, ? and ? of the lines (16).

Abstract: An XDSL system comprising a hybrid circuit in operative communication with a transmission line and an XDSL modem associated with a subscriber premises. The hybrid circuit comprises a plurality of selectable impedance circuits having different impedance values. A controller selectively engages each of the impedance circuits in-line with the XDSL modem and the transmission line. The controller records the performance of the modem with each circuit engaged, and selects the desired impedance circuit as a function of the performance characteristics associated with each of the impedance circuits. The impedance circuit which provides the best performance characteristic is selected as the impedance circuit for normal modem operation.

Abstract: A digital signal line transmission system with reduced echo is provided. A communication line is between a carrier and a user terminal. A bridgetap line has a first end connected to the communication line. An adaptor having a capacitance is connected to the bridgetap line. The adaptor reduces the effect of echo from the bridgetap line on a rate of data transmission to the user terminal over the communication line.

Abstract: A method and apparatus is provided for performing an active impedance differential current feedback. A signal is received. A current feedback of an output signal in an active feedback synthesis mode is performed based upon the signal. The active current feedback includes using an active feedback network for conditioning an output signal, converting the signal into a differential current signal, and summing at least two components of the differential current signal for performing a differential feedback.

Abstract: An XDSL system comprising a hybrid circuit in operative communication with a transmission line and an XDSL modem associated with a subscriber premises. The hybrid circuit comprises a plurality of selectable impedance circuits having different impedance values. A controller selectively engages each of the impedance circuits in-line with the XDSL modem and the transmission line. The controller records the performance of the modem with each circuit engaged, and selects the desired impedance circuit as a function of the performance characteristics associated with each of the impedance circuits. The impedance circuit which provides the best performance characteristic is selected as the impedance circuit for normal modem operation.

Abstract: A system for determining whether a telephone loop is capable of carrying a Digital Subscriber Line (DSL) signal. A Constant Amplitude Zero Auto Correlation (CAZAC) sequence signal is generated and transmitted through the loop plant to a central office and the received echo signal is processed using second-order statistics. The second-order statistics calculation permits determination of the echo signal amplitude and time between the echo signal and sequence signal. The echo signal amplitude and time may be used to obtain telephone loop characteristics such as loop length.

Abstract: A network communication device and hybrid circuit thereof. The hybrid circuit includes a first transformer, a second transformer and a protector electrically connected between the primary winding of the first transformer and the primary winding of the second transformer for protecting transmission function of internet and inhibiting interference of low-frequency signals generated during the communication process.

Abstract: A hybrid system with adjustable on-chip components and a method calibrating the same invariably maximizes hybrid performance despite of on- and off-chip component mismatches and imperfections. The hybrid system has a main DAC, a replica DAC, and three or four resistors. Both DACs are directly connected to digital data. An adjustable resistor is connected to the main DAC and is calibrated such that output impedance is automatically adjusted to match an off-chip load impedance Z. A replica DAC current K is calibrated for optimum DC matching in presence of Z. An adjustable capacitor C2 is calibrated for slope-matching (bandwidth matching). If Z changes, the calibration procedure should be repeated for optimal performance. These three calibration mechanisms can be utilized individually or in combination. The present invention is compatible with both analog and digital echo-cancellers.

Abstract: The present invention relates to a circuit for electronically generating a call impedance in telephone terminals, comprising a call alternating voltage that may be tapped between a first and a second input terminal. The inventive circuit has a regulating device with a programmable digital filter for regulating impedance, wherein the transmission function of the regulating device can be adjusted by programming the filter coefficients of the digital filter. The inventive regulating device makes it possible to adapt the call impedance to different country-specific requirements. To this end, the regulating device has a programmable digital filter that may be embodied as a digital signal processor. In an especially preferred embodiment, the digital filter is implemented in the form of a program in the digital signal processor.

Abstract: An improved analog front end and methods for increasing the power efficiency of duplex signals on a transmission line are disclosed. The improved analog front end bifurcates a hybrid into a fixed portion and an adaptive portion. The adaptive portion combines a biquad and a summer to produce a filter transfer function suited to compensate for transmission line irregularities. A method for configuring a local transceiver to minimize power requirements at a remote transmitter is disclosed. Broadly the method entails, applying a transmit signal to a front end in the absence of a remote signal; optimizing the transmit signal power; recording the reflected transmit signal; applying an adaptive filter in response to transmission line irregularities; and controllably adjusting the adaptive filter to minimize the amplitude of the reflected version of the transmit signal in the receive path. A method for recovering a remotely generated signal is also disclosed.

Abstract: A method and apparatus is provided for impedance matching for an apparatus capable of supporting voice and data. The method includes receiving an input signal having at least one of a voice component, data component, and DC component, and filtering at least a portion of the data component and DC component of the input signal to provide a filtered signal. The method further includes adjusting an input impedance of the apparatus to a first preselected value for the voice band in response to the filtered signal and adjusting the input impedance of the first apparatus from the first preselected value to a second preselected value. The method includes adjusting at least one of a magnitude and phase of the filtered signal to adjust the input impedance to a third value.

Abstract: The present invention relates to broadband line drivers, comprising a cascade connection of an operational amplifier (A) and a transformer (T), which can be integrated on chip. This is obtained by putting the transformer (T) in a feedback loop between the output and the input of the operational amplifier (A).

Abstract: A cordless telephone-to-sound card interface adapter provides a connection between any standard cordless telephone system and a sound card of a computer for PC-to-PC or PC-to-telephone voice communications over the Internet. The interface adapter includes a hybrid transformer circuit for interfacing a two-wire circuit of the cordless telephone and a four-wire circuit of the computer sound card. This hybrid transformer circuit cancels out the voice echo that would otherwise exist due to mismatched impedances between the two media and/or from leakage of the signal being transmitted and received on the same pair of telephone lines. A Universal Serial Bus (USB) plug may be provided to receive a bias voltage from the PC for biasing circuits of the cordless telephone system through the interface adapter. Advantageously, the preferred interface adapter utilizes 100% passive components for a low-cost yet effective means to provide mobility for an end user during voice communications over the Internet.

Abstract: A method for optimizing the transmission properties and power loss of a high voltage part integrated in a subscriber line circuit for connecting a subscriber line wherein, during XDSL data transmission in the high voltage part, current sources which are integrated in the high voltage part and which supply current to the units present in the high voltage part for the purpose of amplifying or measuring telephone signals and/or data signals (which are situated above the frequency band provided for speech), are set, no later than when such data signals are received in the high voltage part, to current values which are higher than the current values for exclusive transmission of telephone signals situated within the voice band provided for speech, such that the data signals within the high voltage part are transmitted with a high bandwidth largely without distortions and the power loss of the high voltage part is optimized.

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: The invention relates to a circuit arrangement for forming the termination of an analogous subscriber line which comprises a first connection and a second connection for connecting a twin-wire analogous subscriber line. Said first connection is linked with said second connection via a series connection of a first capacitor, at least one first adjustable resistor and one second capacitor. According to the invention, a direct current source is linked with the first point of linkage of the first capacitor and the first adjustable resistor. Said direct current source impresses a current which serves to adjust an operating point for voice and data transmission via the analogous subscriber line. The first and the second capacitor block equisignals on the subscriber line so that no direct current can flow via the analogous subscriber line.

Abstract: A load coil is disposed along a local loop for conditioning POTS signals while permitting passage of higher frequency DSL signals with low attenuation. In one embodiment, the load coil includes a coupled inductor having multiple capacitive elements coupled thereto, the capacitive elements facilitating passage of the DSL signals across the load coil.

Abstract: Described herein is a cable length compensator for inclusion in video imaging systems such as X-ray video imaging systems. When such systems are installed at sites of use, cables must generally be installed in the signal path, and the lengths of these cables—which can affect signal resolution—generally cannot be predicted prior to the time of installation. The cable compensator may be situated in the signal path along with the cable to compensate the signal for the effects of the cable so that the desired gain is provided across the desired range of signal frequencies. The compensator includes a low frequency compensation path and a high frequency compensation path, wherein the low frequency compensation path provides a simple gain adjustment to low frequency signals and the high frequency path provides gain adjustment dependent on both signal frequency and cable length.

Abstract: The invention relates to the implementation of narrowband and broadband services in a telecommunications network. A splitter element is connected to a transmission link, the splitter element comprising a passive low-pass filter block connected between the transmission link and a first interface, a high-pass filter unit connected between the transmission link and a second interface, and discrete impedance converting means for adapting the first interface to the characteristic impedance of the transmission link. In order that the impedance matching required by the low-pass filter block may be implemented in an economical way yet maintaining the service quality, the impedance converting means are entirely placed between the interface of the low-pass filter block on the transmission link side and the first interface.

Abstract: A transceiver system is disclosed for use in a telecommunication system. The transceiver system includes a transmission circuit including a transmitter input coupled to an input of a transmission amplifier, a receiver circuit including a receiver output coupled to an output of a receiver amplifier, and a transmission line interface circuit that is coupled to an output of the transmission amplifier and to an input of the receiver amplifier. The transmission line interface circuit includes a matching impedance that is directly coupled to a feedback path of the transmission amplifier and that terminates the transmission line of the transceiver system.

Abstract: A codifier/decodifier (CODEC) filter circuit (250) connected in a subscriber line interface circuit (202) includes a transmit section (264, 262, 260) for converting differential voltage audio transmit signals representing voice transmissions from the subscriber instrument (202) into encoded digital data for transmission to the digital switching network. A receive section (254, 252) coupled between the digital switching network and subscriber instrument (202) within CODEC (250) for converting encoded digital data representing voice signals switched through the digital switching network to differential voltage audio receive signals for transmission to the subscriber instrument (202). The subscriber loop and subscriber instrument (202) reflect the digital voltage audio signals to the transmit section (264, 262, 260).

Abstract: Combined plain old telephone system (POTS) and digital subscriber loop (DSL) line card capable of suppressing low frequency transients. The line card includes the following elements. A DSL receive path receives DSL data from a loop. A POTS receive path receives POTS data from the loop. A combined POTS and DSL transmit path transmits POTS and DSL data to the loop. An impedance generator is coupled between the POTS receive path and the combined POTS and DSL transmit path for synthesizing impedance for signals in the combined POTS and DSL transmit path. A low frequency detector selectively applies a high pass filter to an output of the impedance generator for filtering the low frequency transients. Further, a clipped signal detector and a variable pole high pass filter are provided in the POTS receive path. The clipped signal detector in the POTS receive path triggers a switch that discharges stored transient energy in the receive path.

Abstract: According to a disclosed embodiment, the ideal magnitude and phase of an ideal impedance for interfacing a modem with a telephone line is determined. This ideal impedance can be determined in the presence of an external impedance load and associated circuitry, such as an ADSL modem and accompanying POTS splitter. Thereafter, a model for an interface circuit inside the modem is utilized to arrive at an appropriate impedance for an impedance network inside the interface circuit. As an example, the interface circuit can be a DAA circuit inside a V.90 modem. Then, a relationship between the ideal impedance and an input impedance of the impedance network is established. Thereafter, the impedance network is synthesized to that the relationship between the input impedance of the impedance network and the ideal impedance is in fact satisfied. The impedance network can be, for example, a circuit comprising at least one capacitor.

Abstract: Resistance in parallel with inductors in a series leg of the low-pass filter facilitates changing input and output resistance of the filter with little or no change in the reactance of the inductors. Furthermore, the reactance of the capacitors in the shunt legs of the filter will be substantially unaffected. This assists the designer in matching the impedance of the filter in the pass-band while still providing substantial impedance mismatching in the stop-band without substantially affecting the characteristics of the filter. Facilitating impedance matching in the pass-band and impedance mismatching in the stop-band is accomplished without the need for more complex active components. POTS splitters making use of such filters can facilitate impedance matching of line and load termination in a telecommunications system in response to signals within the frequencies of typical analog telephony service while providing impedance mismatching in response to signals within the frequencies of typical xDSL service.

Abstract: Cascade low-pass filters are useful in attenuating the xDSL band in a POTS splitter. The design of the low-pass filter is a sixth-order filter having two stages. A first stage includes a fourth-order filter, preferably with a stop-band frequency of approximately 48 kHz. A second stage includes a second-order filter in cascade with the fourth-order filter. For this filter, the stop-band frequency is preferably approximately 29 kHz. The inductance value of the second stage is relatively small in comparison to the inductance values of the first stage. In this manner, improvements in xDSL band attenuation are facilitated with little or no eroding of the voice band performance such as insertion loss, pass-band attenuation and return loss.

Abstract: An impedance warping circuit (IWC) and technique for compensating the effect of a blocking capacitor within a transformer of an interface circuit for passing plain old telephone service (POTS) band and asynchronous digital subscriber line (ADSL) band signals on signals having frequencies in the POTS band. The IWC does not significantly affect the performance of the interface circuit in the ADSL band. The IWC synthesizes impedance to compensate the frequency-dependent deviation in the termination impedance across the tip/ring lines. The resulting termination impedance may be designed to conform to the Telcordia Standard of 900 ?+2.16 ?F or other telecommunication standards throughout the entire POTS band.

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 digital subscriber line and POTS voice interface between a telephone line and central office equipment is provided. For POTS band frequencies, a reactive impedance coupled across the two wire interface of the POTS line card, and serially coupled to the line side of the DSL coupling transformer, has an open state magnitude. The magnitude of the line side windings of the DSL coupling transformer is low at POTS band frequencies. POTS band signal power is therefore delivered to the POTS line card. For DSL band frequencies, the reactive impedance across the POTS line card has a closed state magnitude. The POTS line card is therefore essentially short-circuited at DSL band frequencies, and DSL band signal power is delivered to the DSL modem. The frequency band in which the reactive impedance transitions from an open state magnitude to a closed state magnitude corresponds to the frequency band between the POTS frequency band and the DSL frequency band.

Abstract: A novel physical layer transceiver is provided for receiving data transmitted via residential wiring. The transceiver includes an input circuit for receiving an incoming pulse signal, and an energy detector responsive to the incoming pulse signal for producing a pulse energy value representing energy of the incoming pulse signal. An adaptive energy detector gain control circuit is responsive to the pulse energy value for adaptively controlling gain of the energy detector so as to maintain the pulse energy value at a predetermined level. The gain of the energy detector is controlled in response to at least one of access identification pulses preceding data pulses to identify the transmitting station. The adaptive energy detector gain control circuit includes a comparator for comparing a pulse energy value produced by the energy detector with a preset threshold level, and a controller for supplying the energy detector with a gain control value.

Abstract: The invention relates to a method and a circuit for adapting the impedance in a telecommunication connection comprising a speech path and a data path having modems. Conductive properties measured by the modems are used to precisely adjust the impedance on the speech path.