Abstract: A multi-tone transceiver including: a channel controller and a plurality of components forming a transmit path and a receive path. The channel controller configured to determine bit-loading for each successive symbol or tone set based on a 1st noise margin target for a first subset of tones in each tone set dedicated to transport of a robust communications channel (RCC) and based on a 2nd noise margin target less than the 1st noise margin target for remaining tones in each tone set dedicated to a standard communications channel (SCC). The plurality of components forming the transmit and receive paths are responsive to the channel controller to select for data modulated on a given tone at least one of smaller constellations and higher gain scaling levels when the given tone corresponds to an RCC tone as compared to an SCC tone, whereby the first set of tones dedicated to the RCC exhibit greater immunity to noise variations than the remaining tones dedicated to the SCC.

Abstract: An inverse discrete Fourier transform (IDFT) processor processing a lower frequency image of a selected transmit band along with base images of remaining transmit bands called for in a corresponding X-DSL standard. A hybrid upconverter processing the IDFT output by generating a higher frequency replication of the imaged transmit band falling in the standards based frequency range along with the base band images of remaining transmit bands and selectively passing onto the communication medium only images or replications called for by the standards. A hybrid downconverter processing at least one of the received bands at sampling rates below Nyquist thereby creating a lower frequency image within the range of a discrete Fourier transform (DFT) processor. The hybrid downconverter clears the frequency band in which the image processed at sub-Nyquist rates will fold. The DFT then transforms only the images or replications falling within its frequency range.

Abstract: A high efficiency line driver is disclosed. The line driver may be applied with equal advantage in wired and wireless communication media to amplify data signals with a minimum of power consumption. In an embodiment of the invention a line driver is disclosed which includes: at least one amplifier, a delay element, a control signal generator and a generator. The at least one amplifier includes at least one bias supply, a signal input and a signal output. The delay element accepts as an input the data signal and delays delivery of the data signal to the at least one line amplifier for amplification. The generator is responsive to a control signal to generate varying voltage levels corresponding thereto on the at least one bias supply of the at least one amplifier. The control signal generator is responsive to the input data signal to detect peaks therein and to generate the control signal corresponding thereto in advance of delivery of the data signal to the amplifier.

Abstract: An inverse discrete Fourier transform (IDFT) processor processing a lower frequency image of a selected transmit band along with base images of remaining transmit bands called for in a corresponding X-DSL standard. A hybrid upconverter processing the IDFT output by generating a higher frequency replication of the imaged transmit band falling in the standards based frequency range along with the base band images of remaining transmit bands and selectively passing onto the communication medium only images or replications called for by the standards. A hybrid downconverter processing at least one of the received bands at sampling rates below Nyquist thereby creating a lower frequency image within the range of a discrete Fourier transform (DFT) processor. The hybrid downconverter clears the frequency band in which the image processed at sub-Nyquist rates will fold. The DFT then transforms only the images or replications falling within its frequency range.

Abstract: A multi-tone transceiver including: a channel controller and a plurality of components forming a transmit path and a receive path. The channel controller configured to determine bit-loading for each successive symbol or tone set based on a 1st noise margin target for a first subset of tones in each tone set dedicated to transport of a robust communications channel (RCC) and based on a 2nd noise margin target less than the 1st noise margin target for remaining tones in each tone set dedicated to a standard communications channel (SCC). The plurality of components forming the transmit and receive paths are responsive to the channel controller to select for data modulated on a given tone at least one of smaller constellations and higher gain scaling levels when the given tone corresponds to an RCC tone as compared to an SCC tone, whereby the first set of tones dedicated to the RCC exhibit greater immunity to noise variations than the remaining tones dedicated to the SCC.

Abstract: A method and apparatus for extending existing fiber and local area networks across digital subscriber lines, at matching data rates is disclosed. A DSL transceiver system is disclosed with one or more gateways coupled to at least one digital signal processor (DSP). The DSP in turn couples to a plurality of analog-front-ends (AFE's). Each AFE is coupled via associated hybrid front ends (HFE's) to corresponding subscriber lines. The transceiver or a controller coupled thereto maintains a table of bandwidth requirements and frame types for a variety of sessions. Individual sessions include bandwidth requirements beyond existing XDSL capabilities. The system determines frametype, e.g. 802 and bandwidth requirements, e.g. 100 Mbps for each session and allocates more than one subscriber line accordingly. For each session the divergent bandwidth availability of each of the subscriber lines to which the DSP may be coupled is determined and all or a portion of that bandwidth is allocated to the selected session.

Abstract: A high efficiency line driver is disclosed. The line driver may be applied with equal advantage in wired and wireless communication media to amplify data signals with a minimum of power consumption. In an embodiment of the invention a line driver is disclosed which includes: at least one amplifier, a delay element, a control signal generator and a generator. The at least one amplifier includes at least one bias supply, a signal input and a signal output. The delay element accepts as an input the data signal and delays delivery of the data signal to the at least one line amplifier for amplification. The generator is responsive to a control signal to generate varying voltage levels corresponding thereto on the at least one bias supply of the at least one amplifier. The control signal generator is responsive to the input data signal to detect peaks therein and to generate the control signal corresponding thereto in advance of delivery of the data signal to the amplifier.

Abstract: A metallic access test extension system architecture for a digital transmission system is provided. The digital transmission system includes a local end and a plurality of remote ends, each of said plurality of remote ends including a digital communication path and a metallic test pair connection. The local end includes a corresponding digital communication path and corresponding metallic pair connection. The architecture includes a remote unit coupled to each metallic test pair and digital communication path at each of said plurality of remote ends. The remote unit includes a metallic access test extension module. The architecture further includes a central office unit at the local end of the digital communication path, the local end unit including a metallic test extension module and a switch system, responsive to a control signal, for selectively connecting the digital communication paths and metallic test pairs at the local and to the metallic test extension module in the local end unit.

Abstract: The present invention is directed to delta modulation in which the modulation level is optimized to improve overall system performance. A delta modulator in accordance with the invention includes a step size controller having a overload detector, a step size generator and a modulation level regulator. The overload detector monitors the output serial bit stream and produces a signal indicative of whether overload conditions are present. The step size generator produces steps of varying sizes in response to an input signal. The modulation level regulator monitors the signal output from the overload detector and outputs a modulated signal when the overload detector output has reached at least a certain threshold level. The modulation level regulator output is received at the step size generator input.

Abstract: A metallic access test extender includes an office unit and a remote unit coupled to the office unit via a digital transmission system. A voltage controlled current source is included in the office unit and a voltage controlled voltage source in the remote unit. The voltage controlled current source is responsive to the voltage and current sensed at the remote unit load, and the voltage controlled voltage source is responsive to the voltage and current sensed at the input to the office unit. A shunt admittance which has a high impedance at DC and low frequencies is coupled to the office unit load.

Abstract: An origination scan circuit for detecting circuit closure state in a loop circuit has a much lower impedance than does the typical loop circuit. Its source impedance is split into separate resistive parts for connecting opposite terminals of an office battery to the tip and ring leads of the loop. Currents in the separate resistive parts are sensed and summed for comparison against a threshold current to indicate whether or not a subscriber station on the loop is off hook. Threshold current magnitude is variable to accommodate loop start and ground start applications. When the off-hook state is detected, the origination scan circuit is disabled by switching open the resistive part connections, and loop current is thereafter provided by other suitable means. Automatic current limiting arrangements are included for converting the switching functions to high impedance circuit elements.

Abstract: Resistive circuits are provided at the input of an electronic battery feed circuit feedback path for lowering the voltage level of feedback signals to a metallic signal feedback portion and a common mode signal feedback portion so a common mode amplifier can be implemented in a much lower voltage technology than line amplifiers of the battery feed circuit. Additional resistive circuits at the feedback output apply metallic signals to complementary inputs of the tip and ring line amplifiers without requiring a phase splitting amplifier. In addition, signals derived from the feedback circuit are used to vary the supply voltage for the line feed circuit elements as a function of feedback signal level and to provide a common mode reference signal which causes the tip and ring amplifiers to be biased symmetrically with respect to ground and the variable negative supply.

Abstract: A ring-trip detector circuit is disclosed which detects a subscriber off-hook condition in the presence of a ringing signal. The ring-trip detector employs substantially all low-voltage components which enables it to be fabricated using integrated circuit techniques with the resultant cost and space-saving advantages inherent therein. The ringing signal is disabled upon detection of a DC component which is present in the telephone loop only when the subscriber goes off-hook. This circuit detects the DC voltage component across a resistor (20) in series with the ringing source (19) and the telephone loop (12, 13). The voltage across this resistor (20) is converted by resistance networks (23, 24) into two relatively small currents that are fed to low impedance points (25, 26). A difference current is formed therebetween, which is filtered (31, 45) to remove AC components, and compared with a threshold current (29, 46). Ring-trip occurs when the filtered difference current exceeds the threshold.

Abstract: A buck boost type noninverting transformerless switching regulator utilizes two synchronized switches operating at either the same or different duty cycles to independently control energy storage and energy delivery from a two terminal inductor element to the output load. A wide range of output voltage is available and is continuously regulated.

Abstract: A single channel carrier system is disclosed in which carrier techniques are used to add a second private talking path on a normal telephone subscriber loop. A central office unit modulates the second subscriber's signal to an inaudible range while the remote subscriber's unit demodulates this signal to recover the voice signal. The same process is used in the opposite direction utilizing a different carrier frequency.Each unit includes a carrier receiver having automatic gain control circuits and a variable attenuation circuit. The automatic gain control circuit includes a direct current clamp to minimize excursions of the AGC signal in the absence of a received carrier. The variable attenuation circuit uses a diode bridge shunting the signal path and controlled by the AGC signal. A linear carrier oscillator is implemented by providing a constant current source of oscillation energy.

Abstract: A single channel carrier system for telephone service is disclosed including a remote terminal having a battery charger for charging a battery during idle periods to power the remote carrier electronics. The remote electronics include a ringing generator and supervisory circuits to implement normal telephone supervision over the carrier channel.The ringing generator is a DC-to-DC converter for stepping the battery voltage up to ringing voltage level. This high unipolar ringing voltage is then interrupted at a 20 Hz rate during the ringing portion of the ringing cycle. Simple diodes serve to isolate the unipolar ringing signals from other portions of the circuit.