Abstract: An electronic device has a plurality of environments including respective communication stacks. The environments correspond to respective different user personas. Data associated with the different user personas are communicated in corresponding separate transport flows over the network.

Abstract: An electronic device has a plurality of environments including respective communication stacks. The environments correspond to respective different user personas. Data associated with the different user personas are communicated in corresponding separate transport flows over the network.

Abstract: Methods and apparatus are provided related to seismic sensor data. Seismic sensor signaling is digitally sampled in accordance with a local clock and without synchronization to standardized time. Timestamp data is used to synthesize data correspondent to an artificial stimulus waveform. Cross-correlation of the synthesized data with the seismic sensor data yields a correlation result. The correlation result can be scaled to an original starting time for the seismic data sampling. The scaled correlation result can be stored in computer-accessible media and subject to further processing or interpretation.

Abstract: Methods and apparatus are provided related to seismic sensor data. Seismic sensor signaling is digitally sampled in accordance with a local clock and without synchronization to standardized time. Timestamp data is used to synthesize data correspondent to an artificial stimulus waveform. Cross-correlation of the synthesized data with the seismic sensor data yields a correlation result. The correlation result can be scaled to an original starting time for the seismic data sampling. The scaled correlation result can be stored in computer-accessible media and subject to further processing or interpretation.

Abstract: The present invention provides methods for address and name discovery for Ethernet entities. In one aspect, a method is provided for discovering an Ethernet address of a target device in a network having a plurality of devices. The method uses a device name of the target device. A broadcast Ethernet packet includes a source address field and a payload field, the source address field including an Ethernet address of an initiator and the payload field of the broadcast Ethernet packet includes the device name of the target device. The Ethernet packet is broadcast over the network to each device in the network including the target device. The broadcast Ethernet packet is ignored at the devices other than the target device. A response Ethernet packet is received from the target device. The response Ethernet packet includes a destination address field with the Ethernet address of the initiator. The response Ethernet packet also includes the Ethernet address of the target device.

Abstract: A computer network for high-speed data communication, has a data transmission cable with a root and at least one leaf node wherein the upstream transmission is synchronized by information received on a downstream channel. Each client station receives data on a first frequency band, and transmits data on a second frequency band according to synchronization signals received on the first frequency band. The client station's transmission packets may include requests for reserved slots on the second frequency band for subsequent transmissions, and the SCS has a scheduler operable to determine a start time for requested reserved slots, and transmits the start time for the requested reserved slots. The client stations are operable to wait to continue transmission after waiting for the start time.

Abstract: A computer network for high-speed data communication, has a data transmission cable with a root and at least one leaf node. A signal conversion system (SCS) is attached to the root, and at least one client station is attached to a leaf node. The SCS consists of a transmitter that transmits down-stream data onto said cable in a first frequency band; and a receiver that receives data from said client stations on a second frequency band; wherein said down-stream data includes synchronization and acknowledgement signals. Each client station has a receiver that receives data on said first frequency band, and a transmitter that transmits data on a second frequency band according to synchronization signals received on said first frequency band.

Abstract: A computer network for high-speed data communication, has a data transmission cable with a root and at least one leaf node wherein the upstream transmission is synchronized by information received on a downstream channel. Each client station receives data on a first frequency band, and transmits data on a second frequency band according to synchronization signals received on the first frequency band. The client station's transmission packets may include requests for reserved slots on the second frequency band for subsequent transmissions, and the SCS has a scheduler operable to determine a start time for requested reserved slots, and transmits the start time for the requested reserved slots. The client stations are operable to wait to continue transmission after waiting for the start time.

Abstract: A system and method for collision resolution in a communication system having multiple transmission stations communicating on a shared slotted communication channel. The system and method includes a procedure for organizing the stations in a structure wherein each station has a fixed address corresponding to a static location in the structure.

Abstract: An analog, fully integrated, partial response maximum likelihood (PRML) read channel utilizing a high-performance analog delay line, an analog adaptive equalizer and an analog Viterbi detector is provided, resulting in saved space, performance gains, and lower power consumption. For signal detection and reconstruction used in read operations, the partial response maximum likelihood (PRML) read channel includes a variable gain amplifier coupled to a lowpass filter for input to an adaptive analog equalizer. The adaptive analog equalizer comprises an analog delay line and an analog feedforward equalizer (FFE). An analog Viterbi detector employs maximum-likelihood sequence estimation (MLSE) techniques to performs the signal detection function. A decoder/descrambler produces a final reconstructed signal. The analog implementation of a partial response maximum likelihood (PRML) read channel also includes a scrambler/encoder coupled to a write precompensation circuit for output to a separate write head.

Abstract: Signal processing system for reducing error due to intersymbol interference and other noise, the system having a feedforward equalizer adaptively responsive to a first error signal (e.sub.n) and having a noise decorrelator adaptively responsive to an adjusting signal (q.sub.n) derived from the first error signal. In a preferred embodiment the source of the signal (S.sub.n) is a magnetic disk having encoded data thereon. The feedforward equalizer reduces intersymbol interference. A decision device connected to the feedforward equalizer is coupled to connect the signal (X.sub.n) from the feedforward equalizer into a stream (d.sub.n) of data samples having a limited number of predetermined signal levels. The first error signal is the difference between signal levels of data samples in the stream and the output of the feedforward equalizer. The first error signal is utilized to adjust the feedforward equalizer and to provide an input to the noise decorrelator.

Abstract: A technique for eliminating unwanted dc offset voltages in a receiver for decoding a plurality of multilevel digitally modulated signals. The data transmission system is arranged to send a particular preamble signal each time a different data source begins transmission of its data. The preamble signal produces at the receiver output multiple cycles of maximum level excursions. During the period of time that the preamble signal is received, a signal processor in the receiver determines an initial dc offset value by averaging the level of the received digitally modulated signal. After the transmission of the preamble, the signal processor continually generates updated dc offset voltages which are equal to the sum of the previously generated dc offset voltage and the difference between the amplitude level represented by the received digitally modulated signal and the amplitude level of the closest "coding" amplitude level; the difference being multiplied by a scaling factor.

Abstract: In a phase-modulated communication system utilizing voice-band communication channels wherein phase-jumps may be experienced, a phase-jump detector indicates the occurrence of such phase-jumps. A phase-jump corrector responds to the persistence of a phase-jump condition by correcting for it without requiring shut-down and complete reequalization of the transmission channel. Monitoring of the incoming signal for phase-jump occurrence provides a convenient signal quality indication that represents the magnitude of the error in the X and Y components of each received symbol.

Abstract: A phase modulation modem providing switch selectable speeds on voice-band channels utilizes four phase, modified eight phase, and optimized eight phase, two amplitude modulation techniques. A binary equalizer automatically corrects for envelope delay and amplitude distortion of the carrier signal caused by the voice-band channel. Each symbol time, the X-axis error and Y-axis error for the received symbol is determined by comparing the received X and Y components with stored ideal X and Y components for that symbol. These error X and error Y values are used to modify primary and secondary equalization constants. The equalization constants, thus modified during this symbol time, are used on the next received symbol to correct for the phase and amplitude distortion measured during past symbol times. This sequence is repeated for each symbol time. Preselected equalization constants are utilized on the first symbol received.

Abstract: An apparatus capable of transmitting digital data at high data rates over a communication link is disclosed. A carrier signal is modulated by serial groups of digital data signals to be transmitted during a plurality of successively appearing modulation periods. The data-modulated carrier is represented by a unique group of digital signals stored in a memory. The memory upon command, reads out a predetermined sequence of digital signals with each predetermined sequence representing the signal shape of a digital data modulated carrier signal which appears as though it has been passed through a narrow band limited linear phase network. The memory stores a predetermined number of such sequences of digital signals.The number of sequences is four in one preferred embodiment of this invention. In that preferred embodiment, each sequence occupies a spectrum frame which extends in time over four successive modulation periods.