Patent application number | Description | Published |
20090003845 | Automatic Threshold Voltage Adjustment Circuit for Dense Wavelength Division Multiplexing or Packet Transport System and Method of Operating the Same - An automatic threshold voltage adjustment circuit, a method of automatically adjusting threshold voltage and an optical receiver for an optical communication system. In one embodiment, the circuit includes: (1) an amplitude detector configured to detect an amplitude of a received optical signal, (2) a variable resistor coupled to the amplitude detector and including a field-effect transistor configured to operate in a triad mode to provide a resistance that varies substantially linearly based on the amplitude and (3) an operational amplifier coupled to the variable resistor and configured to apply a variable gain based on the resistance to an input threshold voltage to yield an adapted threshold voltage. | 01-01-2009 |
20090121951 | TUNABLE MICROSTRIP DEVICES - Tunable microstrip devices formed by capacitively coupled conductive strips are disclosed. Device parameters can be tuned by adjusting corresponding lengths of a resonator and a coupling section of the device by connecting one or more auxiliary segments to the conductive strips. | 05-14-2009 |
20100028011 | DIGITAL CLOCK AND DATA RECOVERY SCHEME - A method and apparatus providing clock and data recovery within an optical receiver using three CMA FIR filters with different group delays where filter coefficients are adapted to provide for a filter exhibiting a group delay of one sample period from which symbols for further processing are provided. | 02-04-2010 |
20100045550 | Method And Apparatus For A Tunable Channelizing Patch Antenna - A method and apparatus providing a tunable channelized patch antenna by selectively adjoining one or more radiating element extensions successively to a radiating element of the patch antenna, and adjusting fringe capacitance at active outer edges of the patch antenna. | 02-25-2010 |
20100214040 | MULTILAYER PLANAR TUNABLE FILTER - An electronic device includes a first strip conductor formed from a first metal level over a substrate. A second strip conductor formed from a second metal level is located between the first strip conductor and the substrate. At least one of the first and the second strip conductors includes a stripline portion and a microstrip line portion. | 08-26-2010 |
20100247113 | PHASE ERROR CORRECTION IN A COHERENT RECEIVER - A method and apparatus for correcting of phase errors in a coherent optical receiver are disclosed. Embodiments include a method for calculating a phase error between in-phase and quadrature-phase component signals, multiplying the phase error by one of the component signals and subtracting the result from the other component signal to output a corrected signal. | 09-30-2010 |
20100329677 | Symbol Timing Recovery in Polarization Division Multiplexed Coherent Optical Transmission System - A method, apparatus and system for providing clock and data recovery in a receiver for receiving a high speed coherent polarization division multiplexed optical signal using a digital signal processing block including a spectral domain spatial combiner are provided. | 12-30-2010 |
20120008961 | Multiple-Input Method And Apparatus Of Free-Space Optical Communication - An approach is provided that uses diversity to compensate fading of free-space optical (FSO) signals propagating through an environment characterized by atmospheric scintillation. One embodiment involves collecting at least one FSO beam, demultiplexing the beam by wavelength into at least two sub-beams, detecting each sub-beam to produce an electrical output therefrom, and recovering a signal using complementary information from at least two of the electrical outputs. Another embodiment involves collecting the FSO beam onto an array of spatially separated sub-apertures, detecting the light entering each sub-aperture to produce an electrical output therefrom, and recovering a signal using complementary information from at least two of the electrical outputs. This second embodiment enables both electronic adaptive processing to coherently integrate across the sub-apertures and in the case of multiple transmit apertures a free space optical Multiple Input Multiple Output (MIMO) system. | 01-12-2012 |
20120027419 | FRAME/SYMBOL SYNCHRONIZATION IN COHERENT OPTICAL OFDM - One aspect provides an optical communication system. The system includes an optical-to-digital converter, a frequency estimator and a symbol synchronizer. The optical-to-digital converter is configured to receive an optical OFDM bit stream including an OFDM symbol bearing payload data and a symbol header preceding the OFDM payload data. The frequency estimator is configured to determine a carrier frequency offset of the payload data from the symbol header. The symbol synchronizer is configured to determine a starting location of the payload data within the bit stream by cross-correlating a synchronization pattern within the symbol header with a model synchronization pattern stored by the symbol synchronizer. | 02-02-2012 |
20130163988 | BLIND EQUALIZATION FOR POLARIZATION-SWITCHED QPSK OPTICAL COMMUNICATIONS - An apparatus, e.g. an optical receiver, includes an optical front end and an equalizer. The front end is configured for receiving an optical signal bearing first and second symbols on respective first and second polarization channels. The equalizer is configured to 1) select a first cost function if the first symbol has greater energy than the second symbol, 2) select a second different cost function if the second symbol has a greater energy than the first symbol, and 3) based on the selected cost function, update coefficients of an adaptive filter configured to demultiplex and equalize the first and second polarization channels. | 06-27-2013 |
20130287410 | PHASE SKEW COMPENSATION AT A COHERENT OPTICAL RECEIVER - It is disclosed a coherent optical receiver configured to receive a modulated optical signal and to generate an in-phase component and a quadrature component. The optical coherent receiver comprises a phase skew compensator in turn comprising a first digital circuit and a second digital circuit retroactively connected between an output and a control input of the first digital circuit. The first digital circuit provides a compensated in-phase component as a sum of the in-phase component multiplied by a first gain and the quadrature component multiplied by a second gain, and a compensated quadrature component as a sum of the in-phase component multiplied by a third gain and the quadrature component multiplied by a fourth gain. The second digital circuit computes the first, second, third and fourth gain as functions of an estimated cross-correlation between the compensated in-phase component and the compensated quadrature component. | 10-31-2013 |
20140003813 | FORWARD ERROR CORRECTION FOR AN OPTICAL TRANSPORT SYSTEM | 01-02-2014 |
20140070999 | RADIATION EFFICIENT INTEGRATED ANTENNA - An apparatus includes a dielectric slab having first and opposing second major surfaces. A planar antenna element is located on the first major surface. A via formed through the dielectric slab is conductively connected to the antenna element. A plurality of solder bump pads is located on the second major surface and is configured to attach the dielectric slab to an integrated circuit. | 03-13-2014 |
20140072303 | ULTRA DENSE WDM WITH AGILE AND FLEXIBLE DSP ADD-DROP - A system, e.g. for optical communication, includes an I-Q modulator and a transmission signal processor. The I-Q modulator is configured to modulate a first light source in response to first I and Q modulation signals. The transmission signal processor is configured to receive a data stream including data corresponding to a first data subchannel. The processor maps the data subchannel to an optical transmission subchannel and outputs the first I and Q modulation signals. The I and Q modulation signals modulate the light source to produce an optical transmission signal that includes wavelength components corresponding to the optical transmission subchannel. | 03-13-2014 |
20140199063 | GENERATION OF AN OPTICAL LOCAL-OSCILLATOR SIGNAL FOR A COHERENT-DETECTION SCHEME - An optical receiver having an optical IQ modulator configured to generate an optical local-oscillator (OLO) signal for optical homodyne detection of an optical input signal applied to the optical receiver. The optical receiver further has (i) a phase detector configured to generate an electrical measure of the phase difference between the OLO signal and a carrier wave of the optical input signal and (ii) a phase-lock loop configured to drive the optical IQ modulator using the electrical measure. In an embodiment, the phase detector is configured to generate the electrical measure using both I and Q components of the homodyne-detected signal and in a manner that enables the optical receiver to be compatible with the M-QAM modulation format. | 07-17-2014 |
20140199068 | OPTICAL POLARIZATION DEMULTIPLEXING FOR A COHERENT-DETECTION SCHEME - An optical receiver having a plurality of optical IQ modulators arranged in a butterfly configuration and configured to operate as an optical polarization de-multiplexer. The optical receiver further has (i) an opto-electric circuit configured to apply optical homodyne detection to an optical input signal received by the optical receiver and (ii) a controller configured to generate one or more control signals for driving the IQ modulators of the plurality based on one or more electrical feedback signals received from the opto-electric circuit. | 07-17-2014 |
20140292604 | BROADSIDE ANTENNA SYSTEMS - At least one example embodiment discloses an antenna system. The antenna system includes a single printed circuit board (PCB) substrate and an antenna integrated with the single PCB substrate, the antenna being a broadside low-profile microstrip antenna. | 10-02-2014 |
20140356003 | OPTICAL RECEIVER HAVING A CHROMATIC-DISPERSION COMPENSATION MODULE WITH A MULTIBRANCH FILTER-BANK STRUCTURE - An optical receiver having an electronic dispersion-compensation module with two parallel signal-processing branches configured to provide a greater range of dispersion compensation than that provided by a prior-art device of comparable implementation complexity. In an example embodiment, each of the signal-processing branches includes a respective bank of finite-impulse-response filters that are configured in accordance with a different respective approximation of the group delay that needs to be compensated. The two group-delay approximations used by the filter banks rely on different respective step functions, each having a respective plurality of quantized steps, with the transitions between adjacent steps in one step function being spectrally aligned with the flat portions of the corresponding steps in the other step function. The filter banks may be further configured to apply different respective frequency-dependent phase-shift and/or amplitude-scaling profiles designed to reduce signal distortions associated with the transitions between adjacent steps in the step functions. | 12-04-2014 |
20140369392 | MULTI-STANDARD COMPATIBLE COMMUNICATION SYSTEM - In one example embodiment, a communication system includes a remote unit configured to convert a plurality of signals, received at the remote unit from a plurality of end devices, into a plurality of first digital signals regardless of a bandwidth occupied by any of the plurality of signals. The communication system further includes a central unit configured to generate a plurality of second digital signals by processing the plurality of first digital signals received from the remote unit and transmit the plurality of second digital signals back to the remote unit, to be transmitted to the plurality of end devices. | 12-18-2014 |
20150086204 | FREQUENCY-DIVERSITY MIMO PROCESSING FOR OPTICAL TRANSMISSION - An optical transport system configured to transmit information using two or more modulated optical carriers spaced at spectral intervals that are smaller than the baud rate. An example optical receiver in the optical transport system includes a signal equalizer configured to implement frequency-diversity multiple-input/multiple-output signal processing directed at canceling the effects of inter-carrier interference caused by the spectral overlap between adjacent modulated optical carriers to enable the optical receiver to recover individual data streams encoded onto the different modulated optical carriers at the corresponding optical transmitter(s). Some embodiments of the optical transport system may advantageously be capable of achieving a higher spectral efficiency than the spectral efficiency supported by the optical orthogonal-frequency-division-multiplexing transmission format. | 03-26-2015 |