Quaternary Patents (Class 375/281)
  • Patent number: 9473335
    Abstract: Systems and methods are presented for transmitting additional data over preexisting differential COFDM signals by changing the amplitude of the legacy data symbols. In exemplary embodiments of the present invention, additional data capacity can be achieved for a COFDM signal which is completely backwards compatible with existing legacy satellite broadcast communications systems. In exemplary embodiments of the present invention, additional information can be overlaid on a legacy COFDM signal by applying an amplitude offset to the legacy symbols. In exemplary embodiments of the present invention, special receiver processing can be implemented to extract this additional information, which can include performing channel equalization across frequency bins to isolate the amplitude modulated overlay signal.
    Type: Grant
    Filed: May 11, 2012
    Date of Patent: October 18, 2016
    Assignee: Sirius XM Radio Inc.
    Inventors: Carl Scarpa, Edward Schell, Christopher Strolle
  • Patent number: 9014293
    Abstract: Systems and methods for transpositional modulation and demodulation are provided. One such method for generating a signal includes the steps of providing a look-up table having a plurality of quarter-cycle waveforms, each of said quarter-cycle waveforms associated with a respective input level; receiving an input signal; and outputting quarter-cycle waveforms associated with levels of the received input signal. Systems for transpositional modulation are also provided. One such system for generating a signal includes a look-up table having a plurality of quarter-cycle waveforms. Each of the quarter-cycle waveforms are associated with a respective input level, and the look-up table is configured to receive an input signal, and output quarter-cycle waveforms associated with levels of the received input signal.
    Type: Grant
    Filed: March 15, 2013
    Date of Patent: April 21, 2015
    Assignee: TM IP Holdings, LLC
    Inventor: Richard C. Gerdes
  • Patent number: 8948292
    Abstract: In determining an angle for a phase modulation scheme, a key is generated from a prescribed set of bits contained in a symbol. The symbols have an in-phase (I) data word and a quadrature phase (Q) data word that identify coordinates of the symbols in a complex number plane. An angle is retrieved from a memory table from a storage location identified by the key. Each angle in the memory table is established in accordance with constraints under which the memory table was populated so as to be mapped to a phase angle identifying other coordinates in the complex number plane that are within a specified neighborhood about the coordinates of each of the symbols. A signal is generated to convey the symbols as phase differentials at each sample time between a reference phase and the phase angle.
    Type: Grant
    Filed: March 13, 2013
    Date of Patent: February 3, 2015
    Assignee: Exelis Inc.
    Inventor: William J. Taft
  • Patent number: 8743862
    Abstract: In a wireless 802.15.4 communication system (300), a high-speed data frame structure (340) is provided which uses the 802.15.4 SHR structure that is spread modulated to obtain the synchronization benefits of the 802.15.4 protocol, but which uses a modified data frame structure for the payload portion without using spreading to thereby improve its transmission efficiency. The transmission efficiency can be further increased by increasing the size of the data payload (and correspondingly, the frame length size).
    Type: Grant
    Filed: July 1, 2011
    Date of Patent: June 3, 2014
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Clinton C Powell, Kuor-Hsin Chang, Bing Xu
  • Patent number: 8724744
    Abstract: The present invention discloses a method and apparatus for wide dynamic range phase conversion. In one embodiment, inphase and quadrature signal components of a complex input signal are collapsed into a single quadrant to produce a first signal representation. A scaling operation is subsequently performed on the first signal representation to produce a second signal representation. Lastly, the second signal representation is converted into the phase domain.
    Type: Grant
    Filed: August 19, 2005
    Date of Patent: May 13, 2014
    Assignee: General Instrument Corporation
    Inventors: David P. Gurney, Anthony R. Schooler
  • Patent number: 8548105
    Abstract: Techniques for performing joint time-frequency automatic gain control (AGC) by a receiver are described. In an aspect, the receiver may transform time-domain samples with a fast Fourier transform (FFT) to obtain frequency-domain symbols and may detect for saturation of the frequency-domain symbols. The receiver may adjust a gain based on whether saturation is detected and may apply the gain prior to the FFT. In one design, the receiver may use a nominal value for a setpoint if saturation is not detected and may reduce the setpoint if saturation is detected. The receiver may adjust the gain based on the setpoint, which may determine the average power of the time-domain samples. In another design, the receiver may determine the gain based on a gain offset and may vary the gain offset based on whether saturation is detected. For both designs, the receiver may apply the gain on digital samples and/or an analog signal prior to the FFT.
    Type: Grant
    Filed: July 27, 2009
    Date of Patent: October 1, 2013
    Assignee: QUALCOMM Incorported
    Inventor: Roberto Rimini
  • Patent number: 8467461
    Abstract: 2n data transfer signal lines are provided between transmitting and receiving sides of data on n signal lines in order to reduce power consumption required for a data transfer even if the number of bits of data to be transferred increases. The transmitting side has an encoder for outputting a signal of a low potential to one signal line and a signal of a high potential to the other signal lines among the 2n data transfer signal lines in response to an input of transfer data from the n signal lines. The receiving side has a decoder for outputting the similar data as the transfer data to n signal lines in response to inputs from the 2n data transfer signal lines.
    Type: Grant
    Filed: September 11, 2009
    Date of Patent: June 18, 2013
    Assignee: Fujitsu Semiconductor Limited
    Inventors: Hideyuki Amada, Tetsuo Ashizawa, Hideo Akiyoshi
  • Patent number: 8385457
    Abstract: Methods and systems to compensate IQ imbalances in a tuner system, including relatively wideband ZIF tuner systems and tuner systems having substantially linear frequency dependent phase imbalance, where a one-tap compensation element may be utilized to compensate frequency dependent phase imbalance. A two tone probe may be applied in controlled loop-back modes, and resultant baseband components may be used to determine a straight line from which to determine compensation. The probe may include a Multi-Media over Coax Alliance (MoCA) Type 2 probe. Compensation parameters may be determined as fixed or non-adaptive compensation parameters in a digital domain and may be applied at baseband. One or more compensation values may be determined in a fixed point circuit.
    Type: Grant
    Filed: September 23, 2009
    Date of Patent: February 26, 2013
    Assignee: Intel Corporation
    Inventors: Kennan Herbert Laudel, Nicholas Cowley, Isaac Ali
  • Patent number: 8315586
    Abstract: A signal receiving device is provided which can prevent the imbalance occurring between in-phase and quadrature signals. A polarity of a local oscillator output signal to be outputted from a local oscillator 13 is switched by a polarity switching unit 14 in a time division way. Each of signals outputted from the polarity switching unit 14 is frequency divided by a frequency divider 16. The frequency-divided local oscillation signal is supplied to a mixer 34. Frequency conversion of a receiving signal is performed by the mixer 34 which receives the signal and local oscillation signal to demodulate received data.
    Type: Grant
    Filed: September 8, 2009
    Date of Patent: November 20, 2012
    Assignee: NEC Corporation
    Inventor: Yuuichi Aoki
  • Patent number: 8199864
    Abstract: A demodulator for demodulating a digital broadcast signal and a demodulation method thereof. A QPSK demodulator of a digital broadcast reception system includes an in-phase/quadrature (I/Q) detector. The I/Q detector generates a baseband I signal and a baseband Q signal by multiplying a modulated QPSK signal by an I/Q carrier signal. A bandwidth adjustable first filter receives the baseband I signal and the baseband Q signal generated by the I/Q detector and rejects imaginary noise included in the received signals. A data restoration unit restores original data before the signals output from the first filter are QPSK modulated.
    Type: Grant
    Filed: March 2, 2007
    Date of Patent: June 12, 2012
    Assignee: Samsung Electronics Co, Ltd.
    Inventors: Min-ho Kim, Ki-dong Kang
  • Patent number: 8199847
    Abstract: A method and apparatus for providing an asymmetrical backwards compatible communications signal that is capable of being decoded by QPSK and OQPSK receivers as well as PSK and QAM receivers is provided. The invention comprises a timing error accumulator coupled to a first bit stream. The first bit stream includes content that is common to the QPSK/OQPSK receiver and to the PSK/QAM receiver. A phase error accumulator is coupled to a second bit stream and adjusts the phase of symbols in the second bit stream. A phase and timing error compensator is coupled to the phase error accumulator and the timing error accumulator and adjusts the first and second bit streams received from the phase error accumulator and the timing error accumulator in order to reduce timing and phase errors. A higher order modulator coupled to the phase- and timing error compensator is also provided. The higher order modulator processes the first and second bit streams to provide the asymmetrical backwards compatible signal.
    Type: Grant
    Filed: July 18, 2007
    Date of Patent: June 12, 2012
    Assignee: The DIRECTV Group, Inc.
    Inventors: Lin-Nan Lee, Feng-Wen Sun, Mustafa Eroz, Yimin Jiang
  • Patent number: 8189708
    Abstract: A method for controlling code power levels of individual codes of a composite quadrature phase shift keyed (QPSK) signal. The method may involve obtaining a sample of the composite QPSK signal; separating the individual codes from the composite QPSK signal; analyzing the individual codes against corresponding commanded code power settings for the individual codes; and determining a code power correction signal needed for each of the individual codes needed to adjust a code power for each of the individual codes to match their corresponding commanded code power settings.
    Type: Grant
    Filed: August 8, 2008
    Date of Patent: May 29, 2012
    Assignee: The Boeing Company
    Inventor: Armando Benavides
  • Patent number: 8190163
    Abstract: Efficient coding and communication is accomplished by transmitting first and second sets of information using a relatively large transmission block including a plurality of minimum transmission units (MTUs), each MTU corresponding to a unique combination of resources. A first set of MTUs is used in conveying the first set of information, the first set including at least a majority of the MTUs in the transmission block. A second set of the MTUs is defined, e.g., selected, for use in conveying the second set of information, the second set of MTUs including less MTUs than the first set and at least some MTUs included in the first set. The first and second sets of information are communicated by transmitting at least some MTUs included in the first and the second sets of MTUs with the corresponding information modulated thereon.
    Type: Grant
    Filed: August 13, 2003
    Date of Patent: May 29, 2012
    Assignee: QUALCOMM Incorporated
    Inventors: Rajiv Laroia, Murari Srinivasan, Junyi Li
  • Patent number: 8155250
    Abstract: Method and apparatus for a wireless receiver are described which derive at least a first stream of first digitized samples from a received analog signal at a first sampling rate and identify a first frequency offset based on a plurality of parallel correlations using complex reference signals which differ from each other by phase offsets. A second frequency offset is identified based on tracking a demodulation accuracy for each symbol which is demodulated from the first stream of digitized samples. These frequency offsets can be used to rotate decision areas in the demodulator. The methods and apparatus may be used in a Bluetooth receiver.
    Type: Grant
    Filed: August 11, 2006
    Date of Patent: April 10, 2012
    Assignee: ST-Ericsson SA
    Inventors: Pietro Capretta, Steven Terryn, Jean-Jacques Schmit
  • Patent number: 8139688
    Abstract: A differential receiver which provides for estimation and tracking of frequency offset, together with compensation for the frequency offset. Estimation and tracking of the frequency offset is undertaken in the phase domain, which reduces computational complexity and allows frequency offset estimation and tracking to be accomplished by sharing already-existing components in the receiver. Compensation for the frequency offset can be performed either in the time domain, before differential detection, or in the phase domain, after demodulation, or can be made programmably selectable, for flexibility.
    Type: Grant
    Filed: September 29, 2010
    Date of Patent: March 20, 2012
    Assignee: Marvell International Ltd.
    Inventors: Songping Wu, Hui-Ling Lou
  • Patent number: 8121214
    Abstract: A novel and useful apparatus for and method of local oscillator (LO) generation with non-integer multiplication ratio between the local oscillator and RF frequencies. The LO generation schemes presented are operative to generate I and Q square waves at a designated frequency while avoiding the well known issue of harmonic pulling. A synthesizer provides 4/3 the desired frequency fRF. This frequency is divided by two to obtain in-phase and quadrature square waves at ? fRF. The in-phase signal is divided by two again to obtain in-phase and quadrature square waves at ? fRF. The signals are then logically combined using XOR operations to obtain I and Q branch signals containing spectral spurs. Since the spurs are located in non-disturbing bands, they can be filtered out resulting in the desired output signal.
    Type: Grant
    Filed: August 23, 2007
    Date of Patent: February 21, 2012
    Assignee: Texas Instruments Incorporated
    Inventors: Nir Tal, Yossi Tsfaty, Robert B. Staszewski, Gregory Lerner
  • Patent number: 8065586
    Abstract: A radio communication apparatus of the present invention aims at improving an error rate characteristic in the end receiver. A repeater (radio relay device) RS2 receives a signal transmitted from a repeater RS1 at a point of time of signal transmission from the repeater RS1, and detects whether or not an error exists in the signal at a point of time of transmission. Also, when the repeater RS2 detects the error from a systematic bit S of the transmitted signal from the repeater RS1, such repeater RS2 generates error position information EI, replace a part of a parity bit P with the error position information EI, and transmits a resultant signal. The error detection result is notified through the control channel. The mobile station (mobile terminal) MS makes an error correction based on the error position information EI, and demodulates the signal by executing an error correction decoding process.
    Type: Grant
    Filed: May 18, 2006
    Date of Patent: November 22, 2011
    Assignee: Panasonic Corporation
    Inventors: Kenichi Miyoshi, Ayako Horiuchi
  • Patent number: 8050368
    Abstract: A novel and useful apparatus for and method of nonlinear adaptive phase domain equalization for multilevel phase coded demodulators. The invention improves the immunity of phase-modulated signals (PSK) to intersymbol interference (ISI) such as caused by transmitter or receiver impairments, frequency selective channel response filtering, timing offset or carrier frequency offset. The invention uses phase domain signals (r, ?) rather than the classical Cartesian quadrature components (I, Q) and employs a nonlinear adaptive equalizer on the phase domain signal. This results in significantly improved ISI performance which simplifies the design of a digital receiver.
    Type: Grant
    Filed: May 29, 2007
    Date of Patent: November 1, 2011
    Assignee: Texas Instruments Incorporated
    Inventors: Gregory Lerner, Yossi Tsfati
  • Patent number: 8050350
    Abstract: In an I-Q receiver, I-Q baseband mixer receives a real signal, and outputs an in-phase baseband information signal and a quadrature baseband information signal, a decoupling compensator multiplies in-phase baseband information signal and the quadrature baseband information signal by a trained decoupling matrix that, based on adaptive training in response to purely in-phase and purely quadrature phase training signals, decouples the in-phase baseband information signal from a quadrature component of the I-Q signal, and decouples quadrature-phase baseband information signal from an in-phase component of the I-Q signal. Optionally, a trained I-arm-Q-arm imbalance compensator performs a filter compensation on one or both of the decoupled in-phase baseband signal and the quadrature-phase baseband signal output by the trained decoupling matrix.
    Type: Grant
    Filed: December 30, 2008
    Date of Patent: November 1, 2011
    Assignee: NXP. B.V.
    Inventors: Vijay Ahirwar, Mohit Agarwal
  • Patent number: 7995678
    Abstract: A receiver includes a signal input for receiving a differentially-encoded quadrature phase-shift keyed (DEQPSK) communication signal. A demodulator performs bit decisions on a received coherent symbol and bit decisions on a received differential symbol. A processor is operative with the demodulator and scales a soft decision by a factor from 0 to 1 when the results of the bit decisions on the received coherent branch and differential branch are different.
    Type: Grant
    Filed: November 28, 2007
    Date of Patent: August 9, 2011
    Assignee: Harris Corporation
    Inventors: James A. Norris, John W. Nieto
  • Patent number: 7983235
    Abstract: In a wireless 802.15.4 communication system (300), a high-speed data frame structure (340) is provided which uses the 802.15.4 SHR structure that is spread modulated to obtain the synchronization benefits of the 802.15.4 protocol, but which uses a modified data frame structure for the payload portion without using spreading to thereby improve its transmission efficiency. The transmission efficiency can be further increased by increasing the size of the data payload (and correspondingly, the frame length size).
    Type: Grant
    Filed: November 5, 2007
    Date of Patent: July 19, 2011
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Clinton C Powell, Kuor-Hsin Chang, Bing Xu
  • Patent number: 7953033
    Abstract: First and second data is transmitted simultaneously by modulating a first set of signal constellation points, corresponding to the first data, with second data thereby creating a second set of constellation points. The second set of constellation points comprises two subsets corresponding to two values of the first data. The constellation points are selected such that the minimum distance between the first and second subsets is not less than the minimum distance between the constellation points of the first set of constellation points.
    Type: Grant
    Filed: January 7, 2005
    Date of Patent: May 31, 2011
    Assignee: Koninklijke Philips Electronics N.V.
    Inventors: Matthew P. J. Baker, Timothy J. Moulsley, Olivier J-M. Hus, Paul Bucknell, Christoph Herrmann
  • Patent number: 7940639
    Abstract: An IS-OFDM system for point-to-point wireless communications that suppresses narrow-band interference comprises an IS-OFDM transmitter and an IS-OFDM receiver, wherein a transmitted signal comprises a plurality of subcarriers, and further wherein each subcarrier contains more than one and potentially all symbols transmitted in a given frame. The IS-OFDM transmitted signal is at a data rate that is equal to the data rate of the input data stream via the use of P/S converters.
    Type: Grant
    Filed: December 4, 2009
    Date of Patent: May 10, 2011
    Assignee: AT&T Intellectual Property II, L.P.
    Inventor: Diakoumis Gerakoulis
  • Patent number: 7933354
    Abstract: An encoding and/or decoding communication system comprises a framer interface, an encoder, a multiplexer, an output driver, and a clock multiplier unit (CMU). The encoder includes an input latch circuitry stage; an output latch circuitry stage; an intermediate latch circuitry stage interposed between the input latch circuitry stage and the output latch circuitry stage, the intermediate latch circuitry stage coupled to the input latch circuitry stage and the output latch circuitry stage; a plurality of encoding logic circuitry stages interposed between the input latch circuitry stage and the output latch circuitry stage, a last one of the plurality of encoding logic circuitry stages placed adjacent to the output latch circuitry stage and coupled to the output latch circuitry stage; and a feedback between the output latch circuitry stage and the last one of the plurality of encoding logic circuitry stages.
    Type: Grant
    Filed: December 18, 2006
    Date of Patent: April 26, 2011
    Assignee: Semtech Corporation
    Inventors: Samuel A. Steidl, Peter F. Curran
  • Patent number: 7869533
    Abstract: A communication system and method of communicating signals to a plurality of different types of receivers is provided. At least one transmitter transmits hierarchically modulated high priority and low priority signals as a single frequency network. At least one satellite re-transmits the high priority signal in a first circularly polarized direction and the low priority signal in a second circularly polarized direction. At least one of a first receiver having a single antenna is configured to receive the high priority signal in the first circularly polarized direction and switched to receive the low priority signal in the second circularly polarized direction, and a second receiver having a first antenna is configured to receive the high priority signal in the first circularly polarized direction, and a second antenna is configured to receive the low priority signal in the second circularly polarized direction substantially simultaneously.
    Type: Grant
    Filed: August 27, 2007
    Date of Patent: January 11, 2011
    Assignee: Delphi Technologies, Inc.
    Inventors: Glenn A. Walker, Eric A. Dibiaso
  • Patent number: 7844011
    Abstract: An apparatus and method for improving a symbol error rate of an M-ary phase shift keying (M-PSK) system having a quadrature error are provided. The apparatus includes: a conversion parameter detector that detects a conversion parameter and converts a symbol decision region using the quadrature error and at least one pair of first received symbols; and a converter & determiner converting a pair of second received symbols using the detected conversion parameter, and determining a transmission symbol according to a symbol of the converted pair of second received symbols. An increase in a symbol error rate due to the quadrature error can be prevented and the quadrature error can be easily estimated.
    Type: Grant
    Filed: November 2, 2006
    Date of Patent: November 30, 2010
    Assignee: Electronics and Telecommunications Research Institute
    Inventors: Seung Keun Park, Jin A Park, Pyung Dong Cho, Hyeong Ho Lee
  • Patent number: 7809083
    Abstract: A differential receiver which provides for estimation and tracking of frequency offset, together with compensation for the frequency offset. Estimation and tracking of the frequency offset is undertaken in the phase domain, which reduces computational complexity and allows frequency offset estimation and tracking to be accomplished by sharing already-existing components in the receiver. Compensation for the frequency offset can be performed either in the time domain, before differential detection, or in the phase domain, after demodulation, or can be made programmably selectable, for flexibility.
    Type: Grant
    Filed: August 8, 2006
    Date of Patent: October 5, 2010
    Assignee: Marvell International Ltd.
    Inventors: Songping Wu, Hui-Ling Lou
  • Patent number: 7769096
    Abstract: A quadrature-multiplexed continuous phase modulation (QM-CPM) signal is made up of the real parts of two underlying CPM signals whose information content can be recovered from just their real parts. The real parts of two such signals are I/Q multiplexed and transmitted onto a single channel to approximately double the bits/Hz of the underlying CPM signals, while maintaining the same or similar minimum distance. A class of QM-CPFSK (QM-continuous phase frequency shift keyed) signals are presented that use binary signaling but more phase states, and M2-ary QM-CPFSK signals are derived from constant envelope M-ary CPFSK signals. M2-ary multi-amplitude CPFSK signaling schemes are constructed that maintain the same distance as known multi-amplitude CPFSK schemes, but more than double the bandwidth efficiency in bits/Hz. In addition to these CPFSK based embodiments, embodiments are provided that more generally use CPM, non-continuous phase modulated signals, and even trellis-based PAM based signals.
    Type: Grant
    Filed: November 22, 2006
    Date of Patent: August 3, 2010
    Assignee: Trellis Phase Communications, LP
    Inventors: John P. Fonseka, Eric Morgan Dowling
  • Patent number: 7646825
    Abstract: To realize variable control of the output value of impulses with a simple construction, the present device includes an impulse generating unit which generates impulses; and a control unit which controls an output value of impulses output from the impulse generating unit by changing an input signal that is input to the impulse generating unit for generating impulses.
    Type: Grant
    Filed: April 14, 2006
    Date of Patent: January 12, 2010
    Assignee: Fujitsu Limited
    Inventors: Masafumi Asai, Hidenori Sekiguchi, Akira Fujii
  • Patent number: 7630290
    Abstract: An IS-OFDM system for point-to-point wireless communications that suppresses narrow-band interference comprises an IS-OFDM transmitter and an IS-OFDM receiver, wherein a transmitted signal comprises a plurality of subcarriers, and further wherein each subcarrier contains more than one and potentially all symbols transmitted in a given frame. The IS-OFDM transmitted signal is at a data rate that is equal to the data rate of the input data stream via the use of P/S converters.
    Type: Grant
    Filed: December 29, 2006
    Date of Patent: December 8, 2009
    Assignee: AT&T Corp.
    Inventor: Diakoumis Gerakoulis
  • Patent number: 7606321
    Abstract: The system and method enable simpler analog processing in a transmitter by reducing the number of bits in a digital signal through delta sigma modulation. Selection of current sources in a digital to analog converter of the transmitter is done using a randomization circuit.
    Type: Grant
    Filed: June 29, 2004
    Date of Patent: October 20, 2009
    Assignee: Broadcom Corporation
    Inventor: Meng-An Pan
  • Patent number: 7515645
    Abstract: The invention relates to a method for dividing the bit rate of QPSK signals by splitting the spectrum of said QPSK signals into at least two channels having band-limited filters in the modulator and demodulator. The prefiltered QPSK signal is split into at least one real and at least one imaginary spectrum at the transmitter end, is transmitted in frequency multiplex, and the filters in the modulator of the transmitter and the demodulator of the receiver are dimensioned according to the transmission function.
    Type: Grant
    Filed: July 29, 2003
    Date of Patent: April 7, 2009
    Assignee: Interessengemeinschaft für Runfunkschutzrechte GmbH Schutzrechtsverwertung & Co. KG
    Inventors: Willmut Zschunke, Khishigbayer Dushchuluun
  • Publication number: 20090060066
    Abstract: A communication system and method of communicating signals to a plurality of different types of receivers is provided. The communication system includes at least one transmitter that transmits high priority and low priority signals as a single frequency network. At least one satellite receives and re-transmits at least one of the high priority and low priority signals. At least one terrestrial repeater is in communication with the at least one transmitter, and receives from the at least one transmitter and re-transmits at least one of the high priority and low priority signals. A plurality of receivers includes at least a first receiver configured to process the high priority signal to emit an output signal based upon the high priority signal, and a second receiver configured to process the high priority and low priority signals to emit an output signal based upon the high priority and low priority signals.
    Type: Application
    Filed: August 27, 2007
    Publication date: March 5, 2009
    Inventor: Glenn A. Walker
  • Publication number: 20080273555
    Abstract: A system, method and apparatus includes a transmitter that has an encoder and baseband modulator that encodes and modulates a sequence of payload data symbols as a signal constellation to be communicated. An amble generator and baseband modulator generates amble symbols as a known sequence of M symbol times in length every N symbol times. A multiplexer multiplexes the data and amble symbols together to form a communications signal that is transmitted over a communications channel.
    Type: Application
    Filed: May 1, 2007
    Publication date: November 6, 2008
    Applicant: HARRIS CORPORATION
    Inventor: David B. CHESTER
  • Patent number: 7426246
    Abstract: Systems and methods for receiving layered modulation for digital signals are presented. An exemplary apparatus comprises a tuner for receiving a layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom, an analog-to-digital converter for digitizing the layered in-phase signal and the layered quadrature signal and a processor for decoding the layered in-phase signal and the layered quadrature signal to produce one or more discrete layer signals.
    Type: Grant
    Filed: November 22, 2006
    Date of Patent: September 16, 2008
    Assignee: The DIRECTV Group, Inc.
    Inventors: Ernest C. Chen, Tiffany S. Furuya, Philip R. Hilmes, Joseph Santoru
  • Patent number: 7412006
    Abstract: A method includes performing a search method to determine a pair of receiver path correction signals, performing the search method to determine a pair of transmitter path correction signals, and using the pairs of receiver path and transmitter path correction signals to suppress a carrier signal. An apparatus includes a first pair of summers, an upconverter circuit coupled to the first pair of summers, a multiplexer coupled to the upconverter circuit, to a ground, and to an RF front end, a downconverter circuit coupled to the multiplexer, a second pair of summers coupled to the downconverter circuit, and a correction circuit coupled to the first and second pairs of summers.
    Type: Grant
    Filed: July 24, 2003
    Date of Patent: August 12, 2008
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Sumit Talwalkar, Mahibur Rahman
  • Patent number: 7409012
    Abstract: Phase shift key modulators (100, 500, 1000, 1400, 1700) are provided in which a multiphase signal source (108, 1402, 1406-1412,1702) is used to generate a plurality of phases of a carrier signal. A selector (110) is used to select one phase or a sequence of phases of the carrier signal to represent each bit pattern that is received from a binary data source (102, 1422). The multiphase signal source preferably comprises a multiphase oscillator that includes a phase locked ring of variable propagation delay inverters (202). Preferably, a phase sequencer (502) is used to select a monotonic sequence of phases to represent each bit pattern. Preferably two phase selectors (110, 1004) are used to simultaneously select two phases of carrier signal, and a phase interpolator (1106) is used to generate a sequence of phases from the two phases selected by the two phase selectors (110, 1004).
    Type: Grant
    Filed: June 14, 2002
    Date of Patent: August 5, 2008
    Assignee: Motorola, Inc.
    Inventors: Frederick L. Martin, Robert E. Stengel, Edwin E. Bautista
  • Patent number: 7356089
    Abstract: A rotation by a phase offset is applied to symbols to be transmitted by one antenna relative to symbols to be transmitted from another antenna in a wireless communication system employing multi-element antennas at the transmitter. Such a phase offset allows the functionality of a MIMO system to be maintained when a MIMO channel degenerates. Advantageously, a MIMO system using the new signal design may provide a level of performance in a rich-scattering environment that is equivalent to a MIMO system using a known signal design. Furthermore, a MIMO system employing embodiments of the present invention may show significantly improvements in robustness over conventional MIMO systems.
    Type: Grant
    Filed: September 5, 2003
    Date of Patent: April 8, 2008
    Assignee: Nortel Networks Limited
    Inventors: Ming Jia, Peiying Zhu, Wen Tong, Christian Dubuc
  • Patent number: 7319716
    Abstract: In a transceiver comprising a time-division-duplex (TDD) of transmit and receive functions, the characteristics of unwanted image signal energy being transmitted from the transceiver are determined, and thereafter feedback is provided to the transmitter to reduce this unwanted image signal energy. The image signal energy is measured by the receiver component of the transceiver and fed back to the transmitter component of the transceiver. The transmitter component uses the fed back information to adjust the gain and or phase relationship between the quadrature signals that are subsequently quadrature-phase modulated and transmitted. A variety of techniques can be employed to allow the image signal energy to be measured directly by the receiver component. The phase modulation signals at the transmitter can be interchanged, so that the unwanted image signal energy is transmitted in the sideband of the intended signal.
    Type: Grant
    Filed: February 18, 2004
    Date of Patent: January 15, 2008
    Assignee: NXP B.V.
    Inventor: Rishi Mohindra
  • Publication number: 20070286300
    Abstract: The specification and drawings present a new method, system, apparatus and software product for using a new modified dual symbol rate (MDSR) in an uplink direction in mobile communication systems. The communication between the mobile station and the network element may be performed within evolved GSM/EDGE radio access networks. The MDSR can be for example one and a half times a symbol rate of an uplink speech service, e.g., the current GSM/EDGE symbol rate (13/48 MHz) in the mobile communication system, thus the MDSR may be substantially 13/32 MHz or about 405 kHz. The uplink signal with the MDSR may be modulated, e.g., using a quadrature amplitude modulation (QAM), e.g., 16-QAM with 16 states and/or a quadrature phase-shift keying (QPSK, or ?/4-QPSK) modulation.
    Type: Application
    Filed: March 29, 2007
    Publication date: December 13, 2007
    Inventors: Olli Piirainen, Kari Niemela, Jari Hulkkonen, Mikko Saily
  • Patent number: 7305042
    Abstract: A communication system for transmitting (T1) digital communication signals between a transmit site and a receiver site includes an M:1 multiplexer, coupled to a rate 1/N convolutional encoder, which is operative to output an encoded output signal modulated in quaternary phase shift keyed (QPSK) space having a prescribed symbol rate. The receive site has a rate 1/N Viterbi decoder which is operative to decode the encoded output signal output by the rate 1/N convolutional encoder, and a 1:M demultiplexer having an input coupled to the Viterbi decoder and M plurality of outputs, and being operative to demultiplex the decoded signal from the Viterbi decoder into a plurality of M time division multiplexed digital communication signals. For any selected values for of M and N, the product of M and N is constant.
    Type: Grant
    Filed: May 5, 2004
    Date of Patent: December 4, 2007
    Assignee: Adtran, Inc.
    Inventors: Timothy G. Mester, Matthew A. Kliesner
  • Patent number: 7260159
    Abstract: A method and apparatus for providing an asymmetrical backwards compatible communications signal that is capable of being decoded by QPSK and OQPSK receivers as well as PSK and QAM receivers is provided. The invention comprises a timing error accumulator coupled to a first bit stream. The first bit stream includes content that is common to the QPSK/OQPSK receiver and to the PSK/QAM receiver. A phase error accumulator is coupled to a second bit stream and adjusts the phase of symbols in the second bit stream. A phase and timing error compensator is coupled to the phase error accumulator and the timing error accumulator and adjusts the first and second bit streams received from the phase error accumulator and the timing error accumulator in order to reduce timing and phase errors. A higher order modulator coupled to the phase and timing error compensator is also provided. The higher order modulator processes the first and second bit streams to provide the asymmetrical backwards compatible signal.
    Type: Grant
    Filed: May 10, 2002
    Date of Patent: August 21, 2007
    Assignee: The DirecTV Group, Inc.
    Inventors: Lin-Nan Lee, Feng-Wen Sun, Mustafa Eroz, Yimin Jiang
  • Patent number: 7206417
    Abstract: This invention relates to a wireless digital transmission system for loudspeakers comprising: compression means for the file representing the digital audio signal of the “compact disc” type, a transmission device comprising means of converting this compressed signal into a series signal moving by packets going to a modulator circuit with phase quadrature and means of transmitting the signals exiting the modulator circuit with phase quadrature to the domestic network for feeding electricity; a receiving device comprising means of connecting to this domestic network and of extracting from the feed electrical signal, by a demodulator with phase quadrature, data packets moving the digital audio signal to convert it into a parallelized digital signal sent to a decompression circuit; means of converting the decompressed digital signals into an analog signal intended to feed a loudspeaker after adequate amplification.
    Type: Grant
    Filed: December 29, 2004
    Date of Patent: April 17, 2007
    Assignee: Touchtunes Music Corporation
    Inventor: Guy Nathan
  • Patent number: 7173981
    Abstract: Systems and methods for receiving layered modulation for digital signals are presented. An exemplary apparatus comprises a tuner for receiving a layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom, an analog-to-digital converter for digitizing the layered in-phase signal and the layered quadrature signal and a processor for decoding the layered in-phase signal and the layered quadrature signal to produce one or more discrete layer signals.
    Type: Grant
    Filed: February 5, 2002
    Date of Patent: February 6, 2007
    Assignee: The DirecTV Group, Inc.
    Inventors: Ernest C. Chen, Tiffany S. Furuya, Philip R. Hilmes, Joseph Santoru
  • Patent number: 7062228
    Abstract: A cellular communications system may include one or more cellular base stations and a plurality of mobile cellular communications devices for communicating therewith. More particularly, the cellular base station and the mobile cellular communications devices may each include an encoder for generating an information signal. Furthermore, a modulator may generate a modulated waveform based upon the information signal, a carrier signal having a frequency and phase associated therewith, and at least one carrier phase reference symbol. The modulator may also include an offset circuit so that the modulated waveform includes a carrier frequency indicator. A transmitter may also be included for transmitting the modulated waveform to the desired cellular base station or mobile cellular communications device.
    Type: Grant
    Filed: May 10, 2004
    Date of Patent: June 13, 2006
    Assignee: Harris Corporation
    Inventor: Keith Andrew Olds
  • Patent number: 7057538
    Abstract: An encoder circuit and a related method for its operation, in which digital encoding, such as differential phase-shift keyed (DPSK) encoding, is performed as a parallel operation on N bits at a time. Each encoded bit is both output in parallel with the others of the N bits and is coupled as an input to encode the immediately next bit in the input data stream. The Nth encoded bit is fed back to the first encoder stage for use in encoding the (N+1)th bit in the input stream. The encoder typically includes a serial-to-parallel converter at the encoder inputs, and a parallel-to-serial converter at the encoder outputs.
    Type: Grant
    Filed: January 10, 2005
    Date of Patent: June 6, 2006
    Assignee: Northrop Grumman Corporation
    Inventor: Matthew M. D'Amore
  • Patent number: 7016425
    Abstract: The invention proposes the separate processing of the phase and amplitude of multi-amplitude digital modulation techniques, such as a QAM. The phases are differentially modulated and the amplitudes coherently processed. Also proposed is a method to correct the amplitude distortion of the symbols on each subcarrier, either from the QAM signal itself or from any PSK signal, if available. The invention shows that differential modulation/demodulation of multi-amplitude signals with no equidistant phases such as QAM is possible. Complex equalizer means to perform a channel estimation is no more needed as for coherent systems. Further, no pilot sucarriers are needed, thus the bandwidth efficiency is much higher. Furthermore, the frequency snychronization of differential demodulated signals is less complex. An implementation proposal of the new modulation/demodulation technique is described.
    Type: Grant
    Filed: January 13, 2000
    Date of Patent: March 21, 2006
    Assignee: Sony International (Europe) GmbH
    Inventor: Besma Kraiem
  • Patent number: 6980774
    Abstract: A radio frequency (RF) integrated circuit (IC) includes a local oscillation module, analog radio receiver, analog radio transmitter, digital receiver module, digital transmitter module, and digital optimization module. The local oscillation module is operably coupled to produce at least one local oscillation. The analog radio receiver is operably coupled to directly convert inbound RF signals into inbound low intermediate frequency signals based on the local oscillation. The digital receiver module is operably coupled to process the inbound low IF signals in accordance with one of a plurality of radio transceiving standards to produce inbound data. The digital transmitter is operably coupled to produce an outbound low intermediate frequency signal by processing outbound data in accordance with the one of the plurality of radio transceiving standards. The analog radio transmitter is operably coupled to directly convert the outbound low IF signals into outbound RF signals based on the local oscillation.
    Type: Grant
    Filed: March 21, 2002
    Date of Patent: December 27, 2005
    Assignee: Broadcom, Corp.
    Inventor: Hong Shi
  • Patent number: 6973141
    Abstract: A method of baseband/passband digital modulation for a data transmission system wherein a plurality of data symbols is transmitted over a transmission channel at a symbol rate. The method comprises the following steps: (1) generating a plurality of I and Q components of symbols by mapping an input bit stream comprising a plurality of digital codewords into a QAM constellation; (2) selecting a passband or a baseband mode; and (3) generating an analog output signal in the passband or baseband mode. The step of selecting the passband or the baseband mode depends on the complexity of QAM constellation. If QAM constellation includes less than 64 QAM plant points, the passband mode is selected, and if QAM constellation includes more than 64 QAM plant points, the baseband mode is selected.
    Type: Grant
    Filed: October 4, 2001
    Date of Patent: December 6, 2005
    Assignee: Wideband Semiconductors, Inc.
    Inventors: David Bruce Isaksen, Byron Esten Danzer, Mark Fong
  • Patent number: RE39983
    Abstract: A QPSK modulation scheme uses a data spreading mechanism to rob a relatively limited portion of available transmitter power, and inject into the QPSK waveform a prescribed amount of carrier signal power, through which detection and non-regenerative extraction of the carrier at the receiver may be achieved without incurring a signal-to-noise degradation penalty. In addition, the injected carrier-based modulation scheme of the invention may employ high performance forward error correction coding, to significantly reduce the signal power required for achieving a very low energy per bit-to-noise density ratio (Eb/N0)—on the order of one to zero dB.
    Type: Grant
    Filed: August 12, 2005
    Date of Patent: January 1, 2008
    Assignee: Harris Corporation
    Inventors: Raymond F. Cobb, Michael B. Luntz