Patents by Inventor Leif J. Sandstrom

Leif J. Sandstrom has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 9537573
    Abstract: An optical communication system comprises a network interface device (NID) having a media converter coupled to an optical fiber of a passive optical network (PON). The media converter converts optical signals from the PON into electrical signals for communication across at least one non-optical channel, such as a conductive or wireless connection, to customer premises equipment (CPE), such as a residential gateway or other customer premises (CP) device. Rather than implementing an optical media access control (optical MAC) layer in the NID, an optical MAC layer for handling PON protocols and management is implemented by the CPE, thereby effectively extending the customer end of the PON across at least one non-optical connection to the CPE. By implementing the optical MAC layer at the CPE, the complexity of the NID is reduced thereby lowering the cost of the NID.
    Type: Grant
    Filed: January 15, 2015
    Date of Patent: January 3, 2017
    Assignee: ADTRAN, Inc.
    Inventors: Richard Goodson, Leif J. Sandstrom
  • Patent number: 9350447
    Abstract: A communication system comprises a passive optical network (PON) having an optical line terminal (OLT) coupled to a plurality of optical network terminals (ONTs) through a power splitter. Each ONT is coupled to the power splitter via a subscriber line. A switch is coupled to each subscriber line, and all of the switches are coupled to a control element. A power element is configured to receive optical signals communicated by the PON and to convert the optical signals into electrical power for use by the control element. The OLT is configured to detect a rogue ONT and to communicate with the control element for opening the switch that is coupled to the subscriber line of the rogue ONT, thereby optically isolating the rogue ONT from the rest of the PON.
    Type: Grant
    Filed: June 22, 2012
    Date of Patent: May 24, 2016
    Assignee: ADTRAN, Inc.
    Inventors: Thomas Detwiler, Leif J. Sandstrom
  • Patent number: 9306674
    Abstract: The present disclosure generally pertains to optical communication apparatuses having field-tunable power characteristics. In one exemplary embodiment, an optical communication apparatus has an optical transmitter. The optical transmitter is coupled to logic that receives a user input indicative of a desired transmit mode for the transmitter, and the logic then dynamically tunes the transmitter's output power according to the selected transmit mode. In addition, the optical communication apparatus may have an optical receiver for receiving optical signals. The sensitivity of the receiver is controlled by a bias voltage that is applied to the receiver by the logic. The logic is configured to receive a user input indicative of a desired receive mode and then to tune the receiver's sensitivity via the bias voltage according to the selected receive mode.
    Type: Grant
    Filed: December 29, 2014
    Date of Patent: April 5, 2016
    Assignee: ADTRAN, Inc.
    Inventors: Leif J. Sandstrom, Phillip Stone Herron
  • Patent number: 9191102
    Abstract: An optical communication system has a power dissipating element that is thermally coupled to an optical transmitter. The currents supplied to the transmitter and the power dissipating element are controlled such that the sum of such currents is constant. Accordingly, temperature fluctuations in the transmitter due to patterns in the transmitted data are prevented or at least reduced, thereby reducing thermal tails on measurements. In one exemplary embodiment, a light source is used as the power dissipating element, and the output of such light source is beneficially used to probe another optical fiber or to enhance the OTDR performance or analysis.
    Type: Grant
    Filed: March 6, 2013
    Date of Patent: November 17, 2015
    Assignee: ADTRAN, Inc.
    Inventors: Daniel M. Joffe, Leif J. Sandstrom
  • Patent number: 9143228
    Abstract: A small form factor pluggable (SFP) device has an embedded optical time domain reflectometer (OTDR) for detecting anomalies along an optical fiber. The SFP device has a plurality of optical subassemblies (OSAs) that are used to transmit an optical data signal at a first wavelength, transmit an optical OTDR signal at a second wavelength, and receive an optical data signal at a third wavelength. The OTDR signal is effectively isolated from the data signals based on wavelength, and samples of returns of the OTDR signal are analyzed to detect at least one anomaly along the optical fiber.
    Type: Grant
    Filed: March 6, 2013
    Date of Patent: September 22, 2015
    Assignee: ADTRAN, Inc.
    Inventor: Leif J. Sandstrom
  • Publication number: 20150212273
    Abstract: A device includes an optical fiber adapter configured to releasably connect a first optical fiber and a second optical fiber, the optical fiber adapter configured to lenselessly couple an optical signal from the first optical fiber to the second optical fiber and an optical attenuator embedded in the optical fiber adapter, the optical attenuator configured to variably attenuate the optical signal responsive to a control signal.
    Type: Application
    Filed: September 24, 2014
    Publication date: July 30, 2015
    Inventors: Leif J. Sandstrom, Michael J. Tempel
  • Publication number: 20150125151
    Abstract: An optical communication system comprises a network interface device (NID) having a media converter coupled to an optical fiber of a passive optical network (PON). The media converter converts optical signals from the PON into electrical signals for communication across at least one non-optical channel, such as a conductive or wireless connection, to customer premises equipment (CPE), such as a residential gateway or other customer premises (CP) device. Rather than implementing an optical media access control (optical MAC) layer in the NID, an optical MAC layer for handling PON protocols and management is implemented by the CPE, thereby effectively extending the customer end of the PON across at least one non-optical connection to the CPE. By implementing the optical MAC layer at the CPE, the complexity of the NID is reduced thereby lowering the cost of the NID.
    Type: Application
    Filed: January 15, 2015
    Publication date: May 7, 2015
    Inventors: Richard Goodson, Leif J. Sandstrom
  • Patent number: 8965209
    Abstract: An optical communication system comprises a network interface device (NID) having a media converter coupled to an optical fiber of a passive optical network (PON). The media converter converts optical signals from the PON into electrical signals for communication across at least one non-optical channel, such as a conductive or wireless connection, to customer premises equipment (CPE), such as a residential gateway or other customer premises (CP) device. Rather than implementing an optical media access control (optical MAC) layer in the NID, an optical MAC layer for handling PON protocols and management is implemented by the CPE, thereby effectively extending the customer end of the PON across at least one non-optical connection to the CPE. By implementing the optical MAC layer at the CPE, the complexity of the NID is reduced thereby lowering the cost of the NID.
    Type: Grant
    Filed: July 7, 2011
    Date of Patent: February 24, 2015
    Assignee: ADTRAN, Inc.
    Inventors: Richard Goodson, Leif J. Sandstrom, Kevin W. Schneider
  • Patent number: 8948604
    Abstract: The present disclosure generally pertains to optical communication apparatuses having field-tunable power characteristics. In one exemplary embodiment, an optical communication apparatus has an optical transmitter. The optical transmitter is coupled to logic that receives a user input indicative of a desired transmit mode for the transmitter, and the logic then dynamically tunes the transmitter's output power according to the selected transmit mode. In addition, the optical communication apparatus may have an optical receiver for receiving optical signals. The sensitivity of the receiver is controlled by a bias voltage that is applied to the receiver by the logic. The logic is configured to receive a user input indicative of a desired receive mode and then to tune the receiver's sensitivity via the bias voltage according to the selected receive mode.
    Type: Grant
    Filed: December 27, 2010
    Date of Patent: February 3, 2015
    Assignee: Adtran, Inc.
    Inventors: Leif J. Sandstrom, Phillip Stone Herron
  • Patent number: 8718465
    Abstract: N optical transceivers are each connected to a respective electronic module in one-to-one relation such that a respective one electronic module controls a respective one optical transceiver. An electronic switch matrix provides cross-connect capability between the P redundant electronic modules and N electronic modules to the N optical transceivers. A system controller determines when an active N electronic module has failed, and configures the electronic switch matrix to switch a P redundant electronic module into the optical transceiver to which the failed electronic module was connected. A system switch module redirects traffic and routing information, under the direction of the system controller, from the failed module to the newly activated redundant module so that the redundant module assumes the functionality of the failed module.
    Type: Grant
    Filed: March 9, 2011
    Date of Patent: May 6, 2014
    Assignee: Adtran, Inc.
    Inventors: Vahid Sahebekhtiari, Leif J. Sandstrom
  • Patent number: 8699872
    Abstract: An optical communications system includes a MSAP and an optical transceiver mounted at the MSAP that communicates over an optical network to at least one optical network terminal (ONT). A first electronic module is operatively connected to the optical transceiver and configured to control the optical transceiver and mounted at the MSAP separate from the optical transceiver. A redundant second electronic module is supported within the MSAP and mounted separate from the optical transceiver. A Mux/Demux module interconnects and supports the first and second electronic modules to form an integral unit and mounted at the MSAP separate from the optical transceiver. The Mux/Demux module is configured to switch the second electronic module into communication with the optical transceiver upon failure of the first electronic module.
    Type: Grant
    Filed: March 9, 2011
    Date of Patent: April 15, 2014
    Assignee: Adtran, Inc.
    Inventors: Vahid Sahebekhtiari, Leif J. Sandstrom
  • Patent number: 8670667
    Abstract: The present disclosure generally pertains to an arrayed media converter (AMC) that has an array of Wavelength Division Multiplexing-Passive Optical Network (WDM-PON) Optical Network Units (ONUs) for terminating an optical channel in the feeder or distribution portion of a telecommunication network. The ONU converts an optical signal from the optical channel into at least one electrical signal for transmission to a customer premises. Thus, the AMC serves as an interface between at least one WDM-PON link and at least one conductive connection, such as a twisted pair. In one exemplary embodiment, the AMC comprises a sealed housing that is environmentally hardened to protect the AMC from environmental conditions, including changes in weather. Such an AMC may be used to provide a robust, cost effective Fiber To The Curb (FTTC) solution, but the AMC may be used at other points within the network, if desired.
    Type: Grant
    Filed: November 16, 2009
    Date of Patent: March 11, 2014
    Assignee: ADTRAN, Inc.
    Inventors: Leif J. Sandstrom, Kevin W. Schneider
  • Publication number: 20140016938
    Abstract: A tunable channel transmitter system for a wavelength division multiplexed (WDM) passive optical network (PON) includes a WDM communication system having a plurality of WDM channel bandwidths, an injection-locked Fabry-Perot laser having a plurality of resonant modes, a seed light source to provide seed light to the injection-locked Fabry-Perot laser, and a temperature control element configured to shift the plurality of resonant modes of the injection-locked Fabry-Perot laser to ensure that only one resonant mode of the injection-locked Fabry-Perot laser is locked to the seed source and transmitting a substantial portion of the laser power through a desired channel of the WDM communications system.
    Type: Application
    Filed: July 11, 2012
    Publication date: January 16, 2014
    Applicant: ADTRAN, INC.
    Inventors: Leif J. Sandstrom, Kevin Wayne Schneider
  • Patent number: 8606117
    Abstract: A correlation optical time domain reflectometer (OTDR) system embeds an OTDR signal in a digital data signal that is to be converted into an optical signal and transmitted across an optical fiber to a remote receiver. In particular, the digital data signal is amplitude modulated with the OTDR signal, which is based on a pseudo noise (PN) sequence, such as an M-sequence. The amplitude modulation is relatively small, for example, less than about 10% of the digital data signal's peak amplitude in an effort to limit the OTDR signal's effect on communication performance. A sequence recovery element receives reflections from the optical fiber and converts the reflections to digital samples. Each digital sample from the sequence recovery element is correlated by correlators that respectively correspond to delays and, hence, locations along the optical fiber, and accumulators accumulate the correlation values from the correlators.
    Type: Grant
    Filed: May 20, 2010
    Date of Patent: December 10, 2013
    Assignee: ADTRAN, Inc.
    Inventors: Michael D. Turner, Leif J. Sandstrom, John Gordon Brooks, Kevin W. Schneider, Daniel M. Joffe
  • Patent number: 8582969
    Abstract: In accordance with a non-limiting example, an Optical Network Unit (ONU) includes an optical transmitter that has a laser diode and laser driver connected to the laser diode and configured to drive the laser diode so that the laser diode emits an optical communications signal based on transmit data signals. A feedback circuit includes a monitoring photodiode that receives optical feedback signals from the laser diode. A watchdog circuit is connected to the monitoring photodiode and laser driver and includes a logic circuit configured to process the feedback signals and transmit signals to determine if the ONU is rogue. This logic circuit in one example is an XOR logic circuit.
    Type: Grant
    Filed: November 30, 2010
    Date of Patent: November 12, 2013
    Assignee: Adtran, Inc.
    Inventors: Leif J. Sandstrom, Philip D. Williams, Richard L. Goodson
  • Publication number: 20130272694
    Abstract: A small form factor pluggable (SFP) device has an embedded optical time domain reflectometer (OTDR) for detecting anomalies along an optical fiber. The SFP device has a plurality of optical subassemblies (OSAs) that are used to transmit an optical data signal at a first wavelength, transmit an optical OTDR signal at a second wavelength, and receive an optical data signal at a third wavelength. The OTDR signal is effectively isolated from the data signals based on wavelength, and samples of returns of the OTDR signal are analyzed to detect at least one anomaly along the optical fiber.
    Type: Application
    Filed: March 6, 2013
    Publication date: October 17, 2013
    Inventor: Leif J. Sandstrom
  • Publication number: 20130251363
    Abstract: An optical communication system has a power dissipating element that is thermally coupled to an optical transmitter. The currents supplied to the transmitter and the power dissipating element are controlled such that the sum of such currents is constant. Accordingly, temperature fluctuations in the transmitter due to patterns in the transmitted data are prevented or at least reduced, thereby reducing thermal tails on measurements. In one exemplary embodiment, a light source is used as the power dissipating element, and the output of such light source is beneficially used to probe another optical fiber or to enhance the OTDR performance or analysis.
    Type: Application
    Filed: March 6, 2013
    Publication date: September 26, 2013
    Inventors: Daniel M. Joffe, Leif J. Sandstrom
  • Patent number: 8526824
    Abstract: A correlation system, such as a correlation optical time domain reflectometer (OTDR) system, transmits a correlation sequence, such as an M-sequence, and measures the returns of the correlation sequence over time. The system correlates the transmitted sequence with the returns to provide correlation measurement values that respectively correspond to different distances from the point of transmission. A correlation error compensation element adjusts each correlation measurement value in order to cancel the contribution of the correlation error floor from the measurements to provide compensated measurement values that are substantially free of the effects of the correlation error floor.
    Type: Grant
    Filed: August 25, 2011
    Date of Patent: September 3, 2013
    Assignee: ADTRAN, Inc.
    Inventors: Michael D. Turner, Leif J. Sandstrom, John Gordon Brooks
  • Publication number: 20130011142
    Abstract: An optical communication system comprises a network interface device (NID) having a media converter coupled to an optical fiber of a passive optical network (PON). The media converter converts optical signals from the PON into electrical signals for communication across at least one non-optical channel, such as a conductive or wireless connection, to customer premises equipment (CPE), such as a residential gateway or other customer premises (CP) device. Rather than implementing an optical media access control (optical MAC) layer in the NID, an optical MAC layer for handling PON protocols and management is implemented by the CPE, thereby effectively extending the customer end of the PON across at least one non-optical connection to the CPE. By implementing the optical MAC layer at the CPE, the complexity of the NID is reduced thereby lowering the cost of the NID.
    Type: Application
    Filed: July 7, 2011
    Publication date: January 10, 2013
    Inventors: Richard Goodson, Leif J. Sandstrom, Kevin W. Schneider
  • Patent number: 8160187
    Abstract: The present disclosure generally pertains to systems and methods for cancelling crosstalk. A multiple input, multiple output (MIMO) system in accordance with one exemplary embodiment of the present disclosure has a plurality of receivers, which are capable of exchanging information with one another. Each receiver is coupled to a respective subscriber line and receives signals from a remote transmitter. In each path of the MIMO system, in domain crosstalk and possibly some combination of noise, alien crosstalk, and/or other interference such as RF interference, is canceled from the signal being processed. In some cases, a cancellation signal for cancelling crosstalk is based on an output of a symbol decision element, such as a slicer or decoder, thereby improving the accuracy of the cancellation signal.
    Type: Grant
    Filed: February 25, 2008
    Date of Patent: April 17, 2012
    Assignee: ADTRAN, Inc.
    Inventors: Michael D. Turner, Leif J. Sandstrom, John Gordon Brooks