Abstract: A network interface circuit that screens out transient signals and provides an indication to the line side that an actual event has occurred, so that appropriate discrimination circuitry is powered up to determine the exact nature of the actual event only when actually needed. The present invention develops an AC signal that represents the events that are desired to be detected. This AC signal is timed so that it has a sustained rate (e.g., a 1 millisecond burst) that is unlike any transient that would occur on the line. Thus, unless the incoming signal meets the timing requirements of the circuit, it is disregarded as a being a transient and no action is taken to determine the exact nature of the signal. This avoids the need to invoke the discrimination circuits that have large power requirements until they are actually needed.

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: DC transients are removed from a digital filter such as a sigma delta filter (in particular from a sigma delta high pass filter) from the outset by presetting an input summing node to a sigma delta modulator. While the input summing node may be preset using any appropriate input, in a disclosed embodiment, a sigma delta high pass filter is preset by switching a partial feedback term between an input containing the non-zero preset value and the normal input comprising the output from the input summing node. The preset value is chosen based on the value of the zero of the transfer function of the sigma delta high pass filter, e.g., with the complement of the gain factor.

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: Signal processing circuitry having parallel processing channels has clock-generation circuitry that generates (i) high-speed clock signals used to drive the channels and (ii) synchronization signals used to reset the processing of the channels. In one embodiment, the signal processing circuitry has multiple multiplexing channels arranged in one or more macrocells, each macrocell having one or more channels and a phase-locked loop (PLL) that generates a high-speed PLL clock signal and a synchronization signal for the macrocell's channels. Each channel has a counter that implements a state machine used to drive the multiplexing processing, where the state machine is reset to a specified state upon receipt of each synchronization pulse in the synchronization signal.

Abstract: A telephone line interface circuit with event detection capabilities is provided that screens out transient signals and provides an indication to the line side that an actual event has occurred; so that appropriate discrimination circuitry is powered up to determine the exact nature of the actual event only when needed. An event detector develops an AC signal that represents the events to be detected. This AC signal is timed to determine its sustained rate. The sustained rate has a timing threshold which is higher than a transient that occurs on the line. If the incoming signal does not meet the required threshold timing, it is disregarded as being transient and no action is taken. If the incoming signal meets the threshold requirement, the line interface circuit switches to the full power mode and facilitates the actual data transmission.

Abstract: Clock and data recovery circuitry includes an interleaved sampler having multiple integrators, where at least one of the integrators integrates the input data for at least two unit intervals (UIs). One embodiment includes a four-way interleaved sampler, where each integrator in the sampler integrates the input data for two UIs, where each integrator is sampled at or near the middle of its two-UI integration cycle. In an exemplary 10-GHz system, the reset cycle of each integrator may begin many tens of picoseconds after the data is sampled. Since the signal is sampled near the center of the integration cycle and is not highly proximate to the time of the integrator reset, the latch signal has a window of uncertainty extending into the length of a data bit cell with little possibility of latching erroneous data. The sensitivity of the clock recovery circuitry may be optimized by centering the latch function over the time of highest signal level, thereby maximizing signal-to-noise ratio.

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: A communications apparatus supporting seamless integration of VoBB and POTS services can be used with or embodied in any communications appliance or voice/data gateway product that has connectivity to both services. The apparatus supports user-specified usage of one service over another on a call-by-call and/or call-category basis. For example, all long-distance outgoing calls (or those belonging to specific area codes or regions) may be specified to use the VoBB service and all local calls or just emergency “9-1-1” calls may be specified to use the POTS service. The apparatus also enables communication service features such as multiple-line (ML), three-way-calling (TWC), and conference calling (CC)) to be managed intelligently across the VoBB and POTS services.

Abstract: A line powered codec which adaptively allows operation with power supplied from a telephone line in many countries as conditions warrant. A startup procedure uses country-specific register settings, which are powered and maintained from a low voltage side other than the telephone line. Thus, during low line power conditions a programmed state of the line powered codec can be maintained even after a power loss in the telephone line. In another aspect, a current and voltage detection module in the line powered codec is always powered from the telephone line. If sufficient power is not present, the line powered codec does not power up. In yet another aspect, a plurality of power rails may be provided.

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: The present invention provides a digital pre-distortion filter in arrangement with a data access arrangement (DAA) on the component side (e.g., in a modem chipset). This arrangement of the pre-distortion filter outside of the DAA allows digital processes such as digital emulation of the central office impedance to remain unaffected by the pre-distortion in the transmitted signal, allowing the dynamic range of the transmitted signal to be flattened to minimize return loss without complicating the transfer function of the digital emulation of the central office complex load. In the case of a digital emulation filter, placement of a digital pre-distortion filter outside of an analog-to-digital (A/D) digital-to-analog (D/A) loop also minimizes the noise otherwise associated with the use of a pre-distortion filter. Thus, benefits of a pre-distortion filter can be gained without interfering with emulation of impedance, and without causing a significant amount of noise in the transmitted signal.

Abstract: An AC impedance matching architecture which provides programmable AC impedance matching in a given range using a digital filter to filter a signal fed back from the impedance matched line to generate an AC impedance emulation control signal. The AC impedance emulation control signal is combined with a transmit signal (if desired) and drives a voltage controlled current source, which is in parallel with a reference impedance. A voltage is developed across the reference impedance to drive, e.g., the telephone line. The reference impedance is chosen based on a desired maximum AC impedance. The gain of the digital filter, a first order sigma delta filter in the disclosed embodiment, is chosen based on the desired value of the AC impedance. The transfer function of the digital filter is derived based on a desired AC impedance.

Abstract: Telephone line service type identification is provided to a telephone technician in the field by the placement of one or more tuned circuit(s) across the telephone line. In one embodiment, an inexpensive tuned circuit such as a ceramic resonator forms a telecom service resonator ID device which is placed across a telephone line, either at the central office or at the customer premises. Injection of a test current at a predetermined frequency, and a suitable amplitude of the same indicates to the technician aspects of telecom service to that particular telephone line (e.g., the existence of POTS, ISDN, and/or xDSL) and or use of the telephone line by a home network such as HPNA. In another embodiment, a telecom service transponder ID device is formed to provide line service identification to an interrogating line technician. The telecom service transponder ID device is activated when the test signal including an appropriate frequency is present to cause excitation in the telecom service transponder ID device.

Abstract: Telephone line service type identification is provided to a telephone technician in the field by the placement of one or more tuned circuit(s) across the telephone line. In one embodiment, an inexpensive tuned circuit such as a ceramic resonator forms a telecom service resonator ID device which is placed across a telephone line, either at the central office or at the customer premises. Injection of a test current at a predetermined frequency, and a suitable amplitude of the same indicates to the technician aspects of telecom service to that particular telephone line (e.g., the existence of POTS, ISDN, and/or xDSL) and or use of the telephone line by a home network such as HPNA. In another embodiment, a telecom service transponder ID device is formed to provide line service identification to an interrogating line technician. The telecom service transponder ID device is activated when the test signal including an appropriate frequency is present to cause excitation in the telecom service transponder ID device.

Abstract: Embodiments of the present invention are directed to interface devices that provide an interface between a first device and a second device, where the interface device provides electrical isolation between the first device and the second device, and where codec processing is distributed between the first-device side and the second-device side of the interface device. In a preferred embodiment, the second device has a transmission line, the interface device is a modem, and the electrical isolation is provided by one or more digital couplers that transmit sigma-delta signals that are coded and decoded in both the first-device-side and second-device-side circuitries of the modem.

Abstract: A DC termination device particularly adapted for use in a device coupled to a two wire telecommunications system. The termination device controls the tip-to-ring current through the telecommunications device by means of a voltage controlled current source. The control voltage for the voltage controlled current source is provided by digital signal processing of the tip-to-ring voltage such that the tip-to-ring current is linearly proportional to the tip-to-ring voltage when the voltage is below a specified threshold level, but is maintained constant when the tip-to-ring voltage is over the threshold voltage. Preferably, the constant current is the minimum adequate current needed for operation.

Abstract: A telephone line-powered Data Access Arrangement having amplifiers therein directly powered from the telephone line without voltage regulators or filters. The amplifiers, such as the amplifier driving an LED in an optical isolator, draw a constant power supply current independent of the signal being amplified. Thus, amplified signals are not coupled back onto the telephone line.

Abstract: An electronic hybrid useful in telephone line-powered Data Access Arrangements. The hybrid has a transmit amplifier with an output driving the base of a bipolar transistor. The emitter of the transistor is connected to a sense resistor which is, in turn, connected to one wire of a telephone line. The collector of the transistor connects to another wire of the telephone line. A summing node couples together signals on the telephone line and signals across the sense resistor such that the remaining signal on the summing node is substantially the signal received from the telephone line without the signal to be transmitted.

Abstract: A communication card includes a housing and a shank rotatably mounted thereto. The shank defines an axis along its length around which the shank can rotate. A connector is mounted on the shank. The shank and connector are extendable beyond an edge of the housing to an extended position. In the extended position, the connector and shank are rotatable about the shank axis.