Patents Examined by T. Ghebretinsae
  • Patent number: 5566215
    Abstract: In order to restore a clock signal which has been used for coding signals transmitted on a transmission channel, the transition instants of these signals are precisely detected by analyzing a series of samples taken from the signals during at least one fraction of the clock period. A device first determines the deviations between the respective amplitudes of the various samples that have been taken. Comparison of the deviation configuration obtained with standard configurations that have been determined previously makes it possible to estimate the position of the time window where the sampling was achieved in relation to the analyzed period fraction and therefore to decide whether this window is correctly centered. If it is not, a local clock is phase shifted so as to have the time window resynchronized.
    Type: Grant
    Filed: November 6, 1992
    Date of Patent: October 15, 1996
    Assignee: Institut Francais du Petrole
    Inventor: Patrick Coquerel
  • Patent number: 5563905
    Abstract: A system for communicating signals within a digital network without the aid of an array of separate signal lines or of the system data bus. The network communication system 10 of the present invention is operative in accordance with a time-sliced protocol to communicate signal information among a set of digital modules 1. The communication system 10 includes a driver network for transmitting signal information to a first interface circuit 14 in communication with a first 22 of said modules during a selected interval of an interval cycle. The first interface circuit 14 includes an input network 44 for receiving the transmitted information during the selected interval. The inventive network communication system 10 further includes a kickstart circuit 30 for initiating an interval cycle upon the transmission of signal information within the network 10, or upon the execution of a maximum (Nth) interval of a preceding interval cycle.
    Type: Grant
    Filed: September 24, 1992
    Date of Patent: October 8, 1996
    Assignee: Hughes Aircraft Company
    Inventor: Daniel H. Wells
  • Patent number: 5563911
    Abstract: In an equalizer including a plurality of delay elements, a plurality of weighting elements and an adder, the impulse response of a signal transmission channel is estimated to selectively switch over a plurality of selector switches associated with the inputs and outputs of the respective delay elements, thereby selectively changing the combination of the delay elements and the weighting elements transmitting an input signal from the channel to the adder and also changing the combination of the adder and a delay element feeding back the output of the discriminator to the adder. Thus, the number of required taps of the equalizer can be reduced, so that the power consumption and size of the equalizer can be reduced.
    Type: Grant
    Filed: February 28, 1995
    Date of Patent: October 8, 1996
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Mitsuru Uesugi, Kazuhisa Tsubaki, Kouichi Honma
  • Patent number: 5563907
    Abstract: A variable bandwidth filter device for use with a spread-spectrum transmitter including a chipping sequence generator, spread-spectrum processing means, an impulse generator, and a filter. The chipping-sequence generator generates a chipping sequence signal having a chipping-sequence-signal bandwidth. Using the chipping sequence signal, the spread-spectrum processing means processes a data signal to generate a spread-data signal having a spread bandwidth greater than the chipping-sequence-signal bandwidth. In response to each chip in the spread-data signal, the impulse generator generates an impulse signal. The filter filters the spectrum of each impulse signal with a bandpass equal to the spread bandwidth. The invention also comprises a method for generating a spread-spectrum signal using a chipping sequence having a rate less than the spread bandwidth.
    Type: Grant
    Filed: April 17, 1995
    Date of Patent: October 8, 1996
    Assignee: InterDigital Technology Corporation
    Inventor: Gary R. Lomp
  • Patent number: 5555547
    Abstract: In a convolutional coding and Viterbi decoding system transparent to phase skips of .pi. and .pi./2 with applications in TDMA transmission, the transmitter 3 includes a demultiplexer receiving a digital bit stream and operating at the bit timing rate, a QPSK differential coder receiving the demultiplexed bit streams and supplying two coded bit streams, two convolutional coders each supplying one code word, and two multiplexers each receiving one code word from a respective convolutional coder and supplying one component of a symbol to be transmitted. The receiver generates two received symbol components which are applied to two demultiplexers each supplying one code word. Each bit of a code word is applied to a single Viterbi decoder. A QPSK type differential decoder supplies two decoded bit streams which are then multiplexed.
    Type: Grant
    Filed: February 15, 1995
    Date of Patent: September 10, 1996
    Assignee: Alcatel Telspace
    Inventors: Didier Lemaitre, Jean-Pierre Bonin
  • Patent number: 5553078
    Abstract: A communication control system between parallel computers performs a broadcast communication in a network between parallel computer nodes. The communication control system includes a destination detecting unit for detecting the destination information designating the scope of the destination nodes from the data; a between-node distance processing unit for obtaining the distance between the particular computer node and the destination computer node, based on the destination information; and a destination judgment unit for judging whether the data should be obtained by the self node or whether the data should be further transmitted to the other node and for determining the direction of the transmission, based on the distance information.
    Type: Grant
    Filed: January 13, 1995
    Date of Patent: September 3, 1996
    Assignee: Fujitsu Limited
    Inventor: Takeshi Horie
  • Patent number: 5550868
    Abstract: A .pi./4 delay spread detection and compensation arrangement effectively detects distortion due to multipath delay spread in a digital channel and compensates for this distortion with minimum circuit complexity. An improvement in the bit error rate performance for a differential detector in the receiver is achieved through use of a detected direct current (DC) component, which is proportional to the amount of multipath delay spread on the digital channel. This DC component is used in the differential detector for compensating for this delay spread. In addition, the differential detector also provides a channel quality measure of the level of delay spread on the digital channel for use by the receiver in selecting either the differential detector or an equalizer for decoding of the data on the digital channel.
    Type: Grant
    Filed: March 3, 1994
    Date of Patent: August 27, 1996
    Assignee: Lucent Technologies Inc.
    Inventor: Joseph Boccuzzi
  • Patent number: 5550876
    Abstract: The invention relates to a measuring device for measuring the phase deviation of at least a subordinate transport unit of a synchronous signal transmitted through a synchronous transmission system. The measuring device comprises a transmitter unit for forming the synchronous signal to be transmitted, a first desynchronizer for splitting up the synchronous signal and for detecting at least a given byte of the subordinate transport unit, a second desynchronizer for splitting up the received synchronous signal which has passed through the transmission system and for detecting at least the given byte in the received synchronous signal, and an evaluation unit for calculating the phase deviation from the moments of detection of at least the given byte in the transmitted and the received synchronous signals.
    Type: Grant
    Filed: August 25, 1994
    Date of Patent: August 27, 1996
    Assignee: Lucent Technologies Inc.
    Inventor: Ralph Urbansky
  • Patent number: 5550869
    Abstract: A demodulator responsive to a symbol containing analog signal includes a pair of relatively inexpensive analog-to-digital converters for sampling I and Q channels of the signal only once per symbol. A derotator responsive to outputs of the converters and a digital signal representing frequency and phase corrections for an input to the demodulator operates in accordance with a CORDIC function to derive I and Q channel digital signals that are compensated by the corrections. A digital phase shifter responsive to at least one of the digital I and Q signals controls when the input is sampled by the converter.
    Type: Grant
    Filed: December 30, 1992
    Date of Patent: August 27, 1996
    Assignee: Comstream Corporation
    Inventors: Itzhak Gurantz, Yoav Goldenberg, Sree A. Raghavan
  • Patent number: 5548623
    Abstract: A system for the transmission of information between elements of a data processing complex and a method for establishing such a system. Two elements of a data processing system are connected by a physical link comprising multiple conductors attached to transceivers at channels in each data processing element. Once the transceivers have been synchronized, commands and responses are exchanged which ensure that all of the transceivers in a channel are connected to the same channel on the other end of the conductor. If the transceivers are considered configured an entry is made in a Configured-Transceiver table. A search is made of an Allowed-Operational-Link table which contains sets of transceivers which are allowed to become operational links. The set of transceivers thus found, is compared against the Configured-Transceiver-Table to verify that all of the members of the set have been configured. If a match is found, this set of transceivers becomes an Intended-Operational-Link.
    Type: Grant
    Filed: June 1, 1993
    Date of Patent: August 20, 1996
    Assignee: International Business Machines Corporation
    Inventors: Daniel F. Casper, Thomas A. Gregg, Gregory Salyer, Douglas W. Westcott
  • Patent number: 5548617
    Abstract: In a radio receiver for receiving vestigial sideband (VSB) signals including symbol codes descriptive of digital signals, HDTV signals being exemplary of such VSB signals, a tuner provides for selecting one of channels at different locations in a frequency band used for transmitting such VSB signals. The tuner also includes mixers for performing plural conversion of the selected channel to a final intermediate-frequency signal, which is digitized by an analog-to-digital converter. A phase tracker, operative on narrow-bandpass filtered portions of the digitized final intermediate frequency signal centering on its carrier frequency, suppresses an imaginary portion of the final intermediate-frequency signal, arising from multipath distortion or from phase incoherency in local oscillations used during frequency conversion.
    Type: Grant
    Filed: May 19, 1994
    Date of Patent: August 20, 1996
    Assignee: Samsung Elctronics, Co., Ltd.
    Inventors: Chandrakant B. Patel, Allen L. Limberg
  • Patent number: 5546430
    Abstract: This detector is for demodulating a received signal having been previously encoded by a trellis coded modulator and for producing an information data signal with reduced intersymbol interference. The detector comprises a predictor, a delay line, a feedforward filter, an adder, a subtracter, an updater and a trellis coded modulation estimator. The trellis coded modulation estimator has a feedback filter which is adjusted with respect to the feedforward filter to form a decision-feedback equalizer. Moreover, the delay line has a predetermined length which is adjusted according to an order of the feedforward filter and a depth of the trellis coded modulation estimator to achieve a zero relative delay between an output of the feedforward filter and outputs of the trellis coded modulation estimator.
    Type: Grant
    Filed: May 1, 1995
    Date of Patent: August 13, 1996
    Assignee: Universite du Quebeca Hull
    Inventors: Ke-Qiang Liao, Yonghai Gu
  • Patent number: 5544198
    Abstract: The method pertains to wireless transmission in the common-wave operation. For the operation of common-wave networks, it is required that the modulation contents of the transmission frequencies (1 . . . m) transmitted by the individual transmitting stations are identical. However, in order to enable a station or regional identification, one or more regionally differing additional carrier frequencies (n-3 . . . n) are transmitted, whose reception permits the selection of specific regionally related news or messages in the receiver. The demand of additional carrier frequencies may be reduced to four individual frequencies or frequency groups, if these additional carriers are modulated.
    Type: Grant
    Filed: September 10, 1993
    Date of Patent: August 6, 1996
    Assignee: Grundig E.M.V.
    Inventor: Werner Saalfrank
  • Patent number: 5544328
    Abstract: Digital signals, such as digitized television signals, are subjected to a source coding step followed by a channel mapping step. The source coding step causes the signal to be represented by first and second data streams. The first stream carries data regarded as more important and the second carries data regarded as less important. In the channel mapping step, the mapping is such that the data elements of the various data streams have differing probabilities of being erroneously detected at the receiver. The channel mapping step includes at least one multi-level coding step. The signal constellations used in the channel mapping step are partitioned into supersymbols, in which the distance between the symbols comprising at least ones of the supersymbols is less than a parameter referred to as the maximum intra-subset distance (MID).
    Type: Grant
    Filed: October 31, 1991
    Date of Patent: August 6, 1996
    Assignee: AT&T Bell Laboratories
    Inventor: Nambirajan Seshadri
  • Patent number: 5544201
    Abstract: A signal suppressing apparatus for suppressing undesired signal components, in which a first filter electrically simulating a propagation system A of a physical phenomena such as a sound, vibration, electricity, etc. is mounted; a signal having a correlation to the signal to be input to the propagation system A is input to this first filter; and the output of the first filter exerts an influence upon the signal passing the propagation system A to make the passed signal approximate the intended value, wherein the first filter is split into a plurality of filters, each of which is composed by a discrete DSP, outputs are individually calculated in the split individual filters, and the individual calculation results are tabulated, whereby a value the same as the value obtained where the calculation is made without splitting of the first filter is obtained. This enables high speed signal processing even if a high speed DSP is not used.
    Type: Grant
    Filed: July 8, 1994
    Date of Patent: August 6, 1996
    Assignee: Fujitsu Limited
    Inventors: Tsutomu Hoshino, Atsushi Yamaguchi, Tadashi Ohashi, Juro Ohga, Hiroyuki Furuya
  • Patent number: 5541957
    Abstract: A data-transmitting apparatus contains first and second transmitters, a transmit transformer, and a connecting unit for coupling the transformer to an outgoing twisted-pair cable. The first transmitter filters data to produce outgoing data transmitted to the transformer at a first data rate. The second transmitter transmits outgoing data to the transformer at a different, typically greater, second data rate. A data-receiving apparatus contains first and second receivers, a receive transformer, and a connecting unit for coupling an incoming twisted-pair cable to the receive transformer. The first and second receivers receive incoming data from the secondary winding respectively at the first and second data rates. Incoming data is typically provided along data transfer paths that extend from the receive transformer in a daisy chain manner to the receivers. Data moving at either data rate can be transmitted and received without the need for hot switching in the data paths.
    Type: Grant
    Filed: June 15, 1994
    Date of Patent: July 30, 1996
    Assignee: National Semiconductor Corporation
    Inventor: Hung-Wah A. Lau
  • Patent number: 5539773
    Abstract: A method for signal equalization/ghost cancellation with an equalizing filter includes synthesizing a first equalizing filter function (LMS 1) with N (an integer) taps and associated coefficients. The respective coefficients are adjusted to minimize the error between a received reference signal output by the synthesized equalizing filter function and a non-distorted reference signal. The adjusted coefficients are evaluated to determine P (an integer) groups of M (an integer) taps and associated coefficients which contribute to said synthesized equalizing filter function according to a predetermined criterion and wherein P times M is less than N. A second equalizing filter function is synthesized corresponding to the first equalizing filter function with coefficients other than the P groups of M coefficients set to zero, and the P groups to M coefficients are adjusted to minimize the error.
    Type: Grant
    Filed: December 19, 1994
    Date of Patent: July 23, 1996
    Assignee: Thomson Consumer Electronics S.A.
    Inventors: Michael Knee, Andreas Zipp, Andrew Hackett, Nelly Bruneau
  • Patent number: 5539782
    Abstract: An apparatus for restoring a symbol timing of a signal received at a receiving side of a digital communication system.
    Type: Grant
    Filed: April 19, 1995
    Date of Patent: July 23, 1996
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Hyunsoo Shin, Humor Hwang
  • Patent number: 5537441
    Abstract: A method and apparatus for control of concurrent communication of analog information and digital information. In general terms, when the communication channel is viewed as a multi-dimensional space, the digital information signal is divided into symbols, and the symbols are mapped onto the signal space with a preset distance between them. The analog signal, generally limited in magnitude to less than half the distance separating the symbols, is converted to component signals and added (i.e., vector addition) to the symbols. The sum signal is then transmitted to the receiver where the symbols are detected and subtracted from the received signal to yield the analog signal components. The transmitted analog signal is recreated from those components. Both half-duplex and full-duplex operation is available in accordance with this invention. The illustrative embodiment includes a controller that is sensitive to input signals applied to the modem disclosed herein.
    Type: Grant
    Filed: June 14, 1993
    Date of Patent: July 16, 1996
    Assignee: AT&T Corp.
    Inventors: Gordon Bremer, Joseph Q. Chapman, P. Michael Henderson, Kurt E. Holmquist, Kenneth D. Ko, Richard K. Smith
  • Patent number: 5537446
    Abstract: A methodology and concomitant circuitry for smoothing delay sensitive traffic utilizes short term traffic forecasts and guarantees meeting a prespecified delay constraint. The pattern of incoming traffic is used to forecast estimates of future incoming data from the present and past incoming data. Corresponding to the estimate is a data rate for propagating stored data to produce a smoothed outgoing data rate, and the interval of time over which such a rate is used so as to satisfy the delay constraint. The estimation procedure is then re-invoked at the end to the time interval, which takes into account data arriving during the time interval, so as to determine the next succeeding data rate and a new time interval for propagating stored data.
    Type: Grant
    Filed: November 15, 1993
    Date of Patent: July 16, 1996
    Assignee: Bell Communications Research, Inc.
    Inventors: Tirunell V. Lakshman, Teunis J. Ott, Mohammed A. J. Tabatabai-Yazdi