Patents Examined by K. Negash
  • Patent number: 5537634
    Abstract: A tunable optical amplifier is used as a wavelength-selective high-gain element in a subcarrier-multiplexed fiber optic transmission system for providing a direct optical domain-to-baseband conversion of a selected optical channel. A high-speed diode laser optical transmitter is modulated by a plurality of independent information channels that are carried on separate, appropriately spaced carrier frequencies. An optical receiver, coupled to the transmitter by way of an optical fiber, includes a tunable narrow-bandpass semiconductor laser optical amplifier having a gain bandwidth smaller than wavelength distances between adjacent ones of the carrier frequencies, a photodetector coupled to the output of the amplifier, and polarization controlling means coupled to the fiber in front of the optical amplifier for maximizing gain in the optical amplifier.
    Type: Grant
    Filed: February 10, 1992
    Date of Patent: July 16, 1996
    Assignee: GTE Laboratories Incorporated
    Inventor: Donald M. Fye
  • Patent number: 5535031
    Abstract: An apparatus for optically connecting at least two independent half-duplex networks. The apparatus receives electrical signals from a first network, converts these signals to optical signals, and then transmits the optical signals along optical fiber to another apparatus. This apparatus converts the optical signals it receives to electrical signals and transmits the signals to the second network. The apparatus controls the flow signals to and from the networks and optical fibers without any external control signals.
    Type: Grant
    Filed: January 7, 1992
    Date of Patent: July 9, 1996
    Assignee: American Auto-Matrix, Inc.
    Inventor: Warren Cecchini
  • Patent number: 5519526
    Abstract: The invention is a fiber-optic communication network, including a fiber-optic coupler having multiple fiber-optic ports and multiple optical transceivers which are individually connected to one of the fiber-optic pods. Each optical transceivers includes apparatus for transmitting to and receiving from the fiber-optic coupler, optical pulse signals in accordance with a predetermined code sequence of the transceiver, and optical amplifiers for amplifying the optical pulse signals. Each optical transceivers also includes apparatus for spectrally phase encoding/decoding, in accordance with the predetermined code sequence, optical pulse signals being transmitted to and received from its associated fiber-optic port, and apparatus for reconfiguring the code sequence in accordance with a user select signal. Each optical transceivers further includes detection apparatus for detecting a received optical pulse signal transmitted from another of the optical transceivers.
    Type: Grant
    Filed: October 21, 1992
    Date of Patent: May 21, 1996
    Assignee: California Institute of Technology
    Inventors: Peter L. Chua, James L. Lambert, John M. Morookian, Larry A. Bergman
  • Patent number: 5444560
    Abstract: A method of generating a clock signal from a digital optical data signal not having a significant clock component, wherein the digital optical data signal is input into an opto-electronic device and the non-linear variation in the opto-electronic device caused by the digital optical data signal in the device is detected, resulting in the generation of a further signal from the device. A component at a clock frequency for the digital optical data signal is extracted from said further signal.
    Type: Grant
    Filed: August 2, 1993
    Date of Patent: August 22, 1995
    Assignee: British Telecommunications public limited company
    Inventor: Peter E. Barnsley
  • Patent number: 5430568
    Abstract: An optical communications system provides optical signals of different wavelengths over an optical fiber having a zero dispersion wavelength. Electrical dispersion compensating elements independently compensate optical signals having wavelengths different than the zero dispersion wavelength for dispersion in the optical fiber. Limiting radio frequency signals for modulating a light emitting device or laser outputting signals at a wavelength different than the zero dispersion wavelength to less than one octave of frequency permits second order harmonic distortion resulting from dispersion in the fiber to be filtered at a receiving location. The optical communications system may include a reverse transmission path.
    Type: Grant
    Filed: December 1, 1992
    Date of Patent: July 4, 1995
    Assignee: Scientific-Atlanta, Inc.
    Inventors: Frank R. Little, Don E. Frymyer
  • Patent number: 5416623
    Abstract: A line monitoring arrangement of an optical fibre communications system carrying system data signals includes a test sequence generator, an optical transmitter and a correlator. The generator generates a sequence of test pulses, and the optical transmitter repeatedly launches the sequence of test pulses into a first end of a transmission line forming part of the communications system. The correlator correlates signals received at the first end of the transmission line with the sequence of test pulses to identify returned test pulse sequences. The test pulse sequences and system data signals are superimposed onto the transmission line.
    Type: Grant
    Filed: August 30, 1993
    Date of Patent: May 16, 1995
    Assignee: British Telecommunications public limited company
    Inventors: John F. Dawson, Timothy C. Tozer, Simon M. James
  • Patent number: 5406403
    Abstract: A transmitter for a data communication system includes a self configuration register for storing information about the configuration of a local data communication port and a data input register for storing data received from the port to be transmitted and a multiplexer for multiplexing information stored in the self configuration register into configuration data packets and information stored in the data input register into message data packets and transmitting those data packets over an optical fiber. A receiver for a data communication system includes a demultiplexer, an-other configuration register and an output register. The demultiplexer receives data, demultiplexes it and stores it in the output register. The output register transmits information in configuration data packets to the other configuration register and information in message data packets to the local data port.
    Type: Grant
    Filed: September 14, 1992
    Date of Patent: April 11, 1995
    Assignee: Minnesota Mining and Manufacturing Company
    Inventors: Michael E. Griffin, Christopher R. Yungers
  • Patent number: 5402257
    Abstract: In this method and apparatus for the wireless control of a lift device and, in particular, of a traveling crane, a plurality of transmitting units communicate by infrared transmission of data telegrams to a receiving unit associated with the crane. The data telegrams include an integrated address signal that is unique to each transmitting unit and is stored in a memory module of the transmitting unit. The receiving unit decodes the data telegram and, if the crane is not then in use, stores the address signal in a comparison circuit of the receiving unit. Only subsequently-received data telegrams incorporating the stored address signal are passed to the crane for controlling the crane, thereby assuring that a user not then in control of a crane operation cannot interfere with its operation.
    Type: Grant
    Filed: April 8, 1992
    Date of Patent: March 28, 1995
    Assignee: Mannesmann Aktiengessellschaft
    Inventors: Heinz Hasselmann, Anton Munzebrock, Peter Stehr, Walter Voll
  • Patent number: 5398129
    Abstract: In a passive optical telecommunication system in which the signal transmission from a switching center downstream to remote units proceeds in a first stream on a time-division multiplex basis and in which the signal transmission from the remote units upstream to the central switching center proceeds in accordance with a TDMA method in accordance wherewith a remote unit transmits each burst in a synchronized fashion with the assistance of a delay device that is individually set with respect to each remote unit proceeding from the switching center, the remote unit already transmits the bursts before the transmission time required for a desired reception phase relation of the burst in the central switching center only after a rough delay time of a whole system clock period (or system clock periods), and the switching center centrally undertakes a respective individually-dimensioned fine delay of the bursts incoming thereat from each of the remote units into the desired reception phase relation.
    Type: Grant
    Filed: April 24, 1991
    Date of Patent: March 14, 1995
    Assignee: Siemens Aktiengesellschaft
    Inventor: Udo Reimann
  • Patent number: 5396361
    Abstract: A system for stabilizing a frequency separation between two coherent light sources includes first and second current sources driving first and second semiconductor laser devices with first and second frequencies, respectively. Light from the semiconductor laser devices is combined in a multiplexer, and a portion the combined light is diverted to an optical-to-electrical transducer. Output current from the transducer is combined with an output of a local oscillator driven at a selected frequency. A combined signal is then filtered, and used to form a control signal of one of the semiconductor laser devices.
    Type: Grant
    Filed: June 19, 1992
    Date of Patent: March 7, 1995
    Assignee: Hitachi, Ltd.
    Inventors: Shinya Sasaki, Hideaki Tsushima, Minoru Maeda
  • Patent number: 5392148
    Abstract: An optical communicating apparatus has an optical transmitting unit and an optical receiving unit which are accommodated in the same casing. The apparatus is provided with a distributing circuit for supplying a power source to the optical transmitting unit and the optical receiving unit. A modulation device and a demodulation device are connected to the optical space communicating apparatus. The modulation device modulates a transmission signal and has a first power source unit to supply a power source to the distributing circuit. The demodulation device demodulates a reception signal and has a second power source unit to supply a power source to the distributing circuit. A switching device is arranged between the distributing circuit and the first power source unit or between the distributing circuit and the second power source unit.
    Type: Grant
    Filed: December 2, 1992
    Date of Patent: February 21, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventors: Yasuhiro Takahashi, Tetsuo Sakanaka
  • Patent number: 5390038
    Abstract: A data link interface and method are disclosed for controlling signal communications including providing an interface for converting or extending signal communications media in a half-duplex data link between at least two devices or networks and arbitrating the direction of data flow without regard to number of start bits, data bits, or stop bits; without regard to baud rates lower than selected baud rate; or without regard to protocol of the devices on the network.
    Type: Grant
    Filed: June 11, 1992
    Date of Patent: February 14, 1995
    Inventor: Warren P. Cecchini
  • Patent number: 5379141
    Abstract: An optical communications system including a plurality of modulated radio frequency carriers which span more than an octave in bandwidth. In one implementation, the carriers are grouped into ranges which span less than an octave in bandwidth and the individual groups are transmitted over unique optical links. In another implementation, the groups are multiplexed on one optical link by using different wavelengths. In still another implementation, several of the bands are up-converted to the highest band of interest and then transmitted, either over single or multiple links. The resulting optical signals are demodulated and then down-converted before they are recombined into the broadband signal in excess of an octave in bandwidth.
    Type: Grant
    Filed: December 30, 1992
    Date of Patent: January 3, 1995
    Assignee: Scientific-Atlanta, Inc.
    Inventors: Leo Thompson, Frank Little, Rezin E. Pidgeon, Jr.
  • Patent number: 5375004
    Abstract: A light connecting device for routing information uses only light signals. The light connecting device includes photoelectric input/output elements having a light threshold and a light memory, a polarized beam splitter, and light delay circuits having different light delays. The light input signal includes a timing signal and an information signal sequentially input into the beam splitter. The timing light signal is separated from the other signals using the beam splitter and then input into the respective photoelectric input/output elements through the light delay circuits. If the address light signal is incident in synchronization with that of the timing light signal, only the element on which the address and timing lights are simultaneously incident is turned ON and acts as a light amplifier by injecting current to amplify the information signals.
    Type: Grant
    Filed: March 9, 1992
    Date of Patent: December 20, 1994
    Assignee: NEC Corporation
    Inventor: Ichiro Ogura
  • Patent number: 5373382
    Abstract: In a system for the long-distance transmission of a digital signal on a fiber-optic transmission line connecting a transmitter station and a receiver station, the digital signal has rising edges and descending edges between two predetermined signal levels, respectively representing the two binary values that can be assumed by the digital signal, the transmitter station comprising: device for the amplitude modulation of the digital signal, delivering an amplitude modulated signal; device for the modification of the instantaneous optical frequency of the amplitude modulated signal, at the instants corresponding to the rising and descending edges of the digital signal.
    Type: Grant
    Filed: December 22, 1992
    Date of Patent: December 13, 1994
    Assignee: France Telecom
    Inventors: Francis Pirio, Jean-Baptiste Thomine
  • Patent number: 5369350
    Abstract: An optical parallel receiver according to the present invention is provided with a plurality of photodetectors supplied with light signals, respectively, and a reference photodetector receiving a reference light signal having a constant light power equal to that of the received light signals. The reference photodetector supplies an electric signal to be used for generating a DC reference voltage signal. The DC reference voltage signal is used in all of differential amplifiers, respectively.
    Type: Grant
    Filed: December 4, 1992
    Date of Patent: November 29, 1994
    Assignee: NEC Corporation
    Inventor: Kazuhiko Matsuda
  • Patent number: 5369518
    Abstract: A system and a method for providing electrical power to an optical communication system, in particular a telephone system, between a local or central station and a remote station incorporates a conventional fiber optical cable having an electrical conductor or electrically conductive sheath connected to the local station and the remote station already used for transmitting optical signal. A power source is electrically connected to earth ground and to the electrical conductor or sheath at the local station. A power supply is provided at the remote station and electrically connected to the electrical conductor or sheath and to the earth ground thereat. The power supply receives electrical power from the power source located at the local station via the conductor or sheath and the earth ground, the earth ground serving as a return path. The power supply means can thus provide electrical power to an interface device or any other devices provided in the remote station.
    Type: Grant
    Filed: December 18, 1992
    Date of Patent: November 29, 1994
    Assignee: Automated Light Technologies, Inc.
    Inventors: Mohd Aslami, Ronald L. Lavallee
  • Patent number: 5367394
    Abstract: A test apparatus is designed for use with a TPON system including a headend station connected via a fibre optic network to a plurality of terminations. The test apparatus is a self-contained unit including a connection for linking the apparatus to a termination, a first detection circuit which detects status signals generated by the termination, and a second detection circuit which detects alarm signals generated in the head-end station and transmitted to the termination in a downstream data frame. The test apparatus in response to the first and second test circuits provides an output which indicates the condition of the termination. In one example, a series of indicator lamps formed on the housing for the test apparatus are lit to provide the appropriate output.
    Type: Grant
    Filed: April 29, 1993
    Date of Patent: November 22, 1994
    Assignee: British Telecommunications public limited company
    Inventors: Jeremy B. Chuter, Michael A. Hale, Donald E. A. Clarke
  • Patent number: 5365344
    Abstract: A plurality of node apparatuses are connected by an optical transmission line. Each of the node apparatuses is assigned with a wavelength as an address different from the others. Therefore, when a first node apparatus transmits data to a second node apparatus, the data is of a wavelength corresponding to the address of the second node apparatus. The data transmission is carried out in a time slot defined by a frame pulse. The data of the corresponding wavelength is only received in the second node apparatus, and data of other wavelengths are passed through the second node apparatus. Consequently, media-access control is easily carried out independently in each node apparatus in an optical network system by using wavelength division multiplexing.
    Type: Grant
    Filed: June 25, 1992
    Date of Patent: November 15, 1994
    Assignee: NEC Corporation
    Inventors: Masahiro Eda, Masahiko Fujiwara
  • Patent number: 5359449
    Abstract: An optical transmitter having a Mach-Zehnder optical modulator comprising a signal electrode fed with a driving signal for effecting modulation and a bias electrode for operating point control. Because the signal electrode and the bias electrode are independent of each other, a driving circuit and the signal electrode can be connected in a DC setup. This permits stable operating point control and improves waveform characteristics.
    Type: Grant
    Filed: November 19, 1992
    Date of Patent: October 25, 1994
    Assignee: Fujitsu Limited
    Inventors: Hiroshi Nishimoto, Hironao Hakogi, Takatoshi Minami