Abstract: A cable modem communicates the timing of the arrival of certain packets (such as TCP ACK packets) to a cable modem termination system. This timing feature is useful in methods for increasing the throughput in the downstream direction by eliminating TCP ACKs backing up at a cable modem. In particular, a cable modem termination system implementing an unsolicited bandwidth grant service in which unsolicited grants of bandwidth are sent by the cable modem termination system to the cable modem. The grants of bandwidth are timed to arrive at the cable modem simultaneous with or shortly after the arrival of the TCP ACK from an end station connected to the cable modem. Several methods of calculating or predicting when the unsolicited grants should be sent to the cable modem are described. The method is also applicable to other types of packets, such as voice packets from a end station implementing a Voice over Internet Protocol (VoIP) application.

Abstract: A system and method for communicating data between a user connected to a subscriber line and a data network comprising a first module connected to the subscriber line and a second module, physically separate from the first module, connected to the data network. The first module includes a signal converter for converting analog signals received from the subscriber line to a digital signal for sending over an interconnection path to the second module. The second module includes a modulator/demodulator for converting the digital signal to data packets. The first module may be pooled with M first modules and connected over a shared interconnection path to N second modules. The interconnection path may be concentrated to permit communication of signals from those first and second modules communicating user data at any given time.

Abstract: A method and device for providing telephone subscribers serviced from digital loop carrier (“DLC”) systems access to a computer network. The described device includes a redirect repeater with the capability to redirect multiplexed channels of the DLC to a computer network. The redirect repeater is interfaced to the DLC and redirects channels of the multiplexed DLC system to the computer network in response to a redirect signal. The described method includes monitoring the DLC for a call origination message indicating a subscriber is originating a telephone call, buffering messages from the originating telephone call and recognizing a redirect signal indicating the telephone call is to be directed to the computer network. Messages indicating the telephone call is redirected to the computer network are inserted and the messages from the telephone call can then be redirect to the computer network.

Abstract: Apparatus and method for managing transmission of digital data between a digital telephone line and a computer network. First and second modems, a telephone control circuit and a network control circuit respond to management instruction signals to execute predetermined management objectives and generate management response signals representing one or more conditions of the first and second modems, telephone control circuit and network control circuit. In response to a single packet of management signals from the network, a management circuit generates the management instruction signals and independently addresses them to one or more of the first and second modems, telephone control circuit and network control circuit.

Abstract: An inverter control for an N phase inverter includes a single memory which stores a plurality of bytes, circuitry coupled to the memory for developing a series of memory addresses for each phase output of the inverter, each series of memory addresses defining a phase output waveform to be produced and circuitry coupled to the developing circuitry for accessing the memory with a memory address from each series thereof during each of a number of accessing cycles so that N bytes are provided at an output of the memory during each accessing cycle. A demultiplexer is coupled to the memory for deriving gating signals for switches in the inverter from the bytes provided at the output of the memory.

Abstract: A digitally controlled oscillator (DCO) includes a binary full adder having a first set of inputs coupled to input lines, a second set of inputs, a set of summation outputs and a carry output. A latch is provided having a set of latch inputs each coupled to one of the outputs of the binary full adder, a clock input and a set of latched outputs each coupled to one of the second set of inputs of the binary full adder wherein the binary full adder sums the bits of a latched period command signal which is provided on the input lines with bits appearing at the latched outputs and provides a summed value to the summation and carry outputs. A finite state machine is coupled to the carry output of the binary full adder and to the clock input of the latch wherein the machine produces the oscillator signal having a period determined by the period command signal.

Abstract: Prior variable speed constant frequency (VSCF) generating systems which utilize an inverter to derive constant frequency power from variable frequency power developed by a generator driven by a prime mover have controlled system output voltage by controlling the excitation of the generator. Such a control technique, however, does not provide voltage regulation of individual phases and minimize undesirable distortion in the system output. In order to overcome the foregoing problem, a control for a VSCF system having a generator and an inverter which receives DC power from a rectifier coupled to the generator controls switches in the inverter to maintain the voltage of the AC power developed by the inverter at a desired level and controls the power applied to an exciter of the generator to maintain the voltage of the DC power at a particular level relative to the voltage of the AC power developed thereby. Distortion in the inverter output is thereby minimized.

Abstract: In aircraft applications, it may be necessary or desirable to transfer one or more loads between a variable speed, constant frequency (VSCF) power generating system and a further source of AC power. Prior controls for effecting such transfer, however, have been unduly complex. In order to overcome this problem, a control for a VSCF system senses the deviation of a parameter of the power developed by an inverter of the system relative to a parameter of the power developed by an AC power source and controls the inverter in accordance with such deviation to cause the parameter of the power developed thereby to approach the parameter of the power developed by the AC power source. The inverter and the AC power source are connected in parallel across one or more loads when the parameter deviation is within a certain range. Either the inverter or the AC power source is thereafter disconnected a certain time after the two were connected in parallel to complete the power transfer.

Abstract: Prior variable speed constant frequency (VSCF) system controls which operate the VSCF system while it is coupled in parallel with an external AC source across a load have controlled inverter output voltage based only upon the reactive current level supplied by the inverter. This has in turn resulted in the possibility of unstable system operation under load. In order to overcome the foregoing problem, a control for controlling the supply of power to a load from an inverter coupled in parallel with an AC power source across the load senses the real and reactive components of the current supplied by the inverter and the phase displacement of the power developed by the inverter relative to the power developed by the AC power source to derive an angular displacement signal.

Abstract: Power inverters for converting DC power into AC power often produce a DC component in the inverter output which is objectionable. In order to overcome this problem, an inverter control according to the present invention detects the magnitude of the DC component in the inverter AC output power and adjusts the time of selected rising and falling edges of control waveforms for switches in the inverter to reduce the magnitude of the DC component.

Abstract: At times, it may be necessary to operate switches of a PWM inverter to provide a low output voltage. However, in order to produce such a low voltage, it may be necessary to operate the switches near their minimum on time limit, which can in turn lead to damage or destruction of the switches. In order to overcome this problem, a control for an inverter which produces an output voltage having two levels wherein the inverter includes first and second switches coupled to an inverter output produces first and second switch control signals each having alternating switch on and switch off portions wherein each switch on portion is of a duration in excess of the minimum on time limit of the switches.

Abstract: Polyphase inverters for converting AC power into polyphase AC output power typically experience phase shifts due to unbalanced phase loading. The resulting phase error is undesirable and should be eliminated, if possible. In order to overcome the foregoing problem, a control for maintaining N-1 phase outputs at desired angular displacements relative to a reference phase output determines the angular deviation of each of the N-1 phase outputs from the desired angular displacement for such phase output and adjusts a control waveform in time for each of a number of switches based upon the angular deviation of the phase output produced by such switch so that the angular deviations are minimized.