# Carrier recovery circuit or carrier tracking

## Subclass of:

## 375 - Pulse or digital communications

## 375316000 - RECEIVERS

## 375322000 - Angle modulation

## 375324000 - Particular demodulator

### Patent class list (only not empty are listed)

#### Deeper subclasses:

Class / Patent application number | Description | Number of patent applications / Date published |
---|---|---|

375326000 | Carrier recovery circuit or carrier tracking | 33 |

20100040175 | SIGNAL PROCESSING METHOD, SIGNAL PROCESSING DEVICE, WIRELESS RECEPTION DEVICE, AND COMMUNICATION RECEPTION DEVICE - It is possible to realize an ideal software reception device which can demodulate a higher-order modulation signal without losing vector information even if a carrier wave is sampled with a frequency lower than the carrier wave. A sampling frequency is set so that a phase relationship of the sampling point of an alias signal generated by sampling of a carrier with a sampling frequency lower than the carrier wave coincides with a phase relationship of the sampling point of the carrier wave. That is, the sampling frequency is set so that the carrier wave frequency “f | 02-18-2010 |

20100142651 | FRAME-BASED CARRIER FREQUENCY AND PHASE RECOVERY SYSTEM AND METHOD - Header information is used to facilitate coarse frequency and frame recovery. The coarse frequency and frame recovery is thereafter utilized to perform adaptive phase and frequency synchronization on a frame-by-frame basis. | 06-10-2010 |

20090092204 | DETECTION CIRCUIT AND DETECTION METHOD OF CARRIER OFFSET - A carrier offset detection circuit is offered, which is provided to a demodulation circuit which demodulates a received signal subjected to FSK (Frequency Shift Keying) modulation, and which detects the offset of the carrier frequency between the transmitting side and the receiving side. A zero-crossing detection unit receives a digital base band signal indicating the level of the frequency shift (frequency deviation) of the received signal using the carrier frequency on the receiving side as a reference frequency, and detects a zero-crossing point of the base band signal and a base band signal obtained by delaying the former base band signal by one symbol, which occurs in a preamble period. A carrier offset detection circuit sets the offset value of the carrier frequency to the value of the base band signal at a timing of the zero-crossing point thus detected. | 04-09-2009 |

20120269297 | CARRIER FREQUENCY OFFSET ESTIMATION SCHEME, FOR DIGITAL STANDARDS WITH MPSK MODULATED PREAMBLE - A receiver for reducing acquisition time of a Carrier Frequency Offset (CFO) of an input intermediate frequency (IF) signal with M-PSK modulated preamble using spectral based analysis is provided. The receiver includes an analog to digital converter that converts the input IF signal into a digital signal, a down conversion unit that down converts the digital signal to a baseband complex signal, and a CFO estimation block that estimates the CFO. The CFO estimation block includes a carrier harmonic generation unit that generates an output of carrier M | 10-25-2012 |

20100074374 | PHASE CALIBRATION CIRCUIT AND RELATED PHASE CALIBRATION METHOD - A phase calibration circuit applied to at least one signal processing module group includes at least two phase calibration modules, a phase detection module and a filter module. An output node of a first phase calibration module is coupled to an input node of a first signal processing module, an input node of a second phase calibration module is coupled to an output node of the first signal processing module, and the first signal processing module receives a calibrated signal outputted from the first phase calibration module and generates a processed signal. The phase detection module is utilized for generating a phase error signal according to a calibrated signal of an M | 03-25-2010 |

20110069789 | METHOD AND SYSTEM FOR CARRIER RECOVERY FOR QAM - Systems and methods of carrier frequency acquisition or recovery in a receiver. The receiver is able to achieve carrier acquisition when a frequency offset is large (e.g., near a decision boundary). The receiver includes a demodulator, an equalizer, and a carrier recovery module. The carrier recovery module includes a decision device and phase detector, a phase error differentiator, a frequency direction confidence module, and a frequency and phase combiner module. The carrier recovery module calculates a phase error differential between a phase error at a first time and a phase error at a second time. Based on the phase error differential, the frequency direction confidence module generates a frequency offset confidence number. The frequency offset confidence number provides an indication of the direction of a frequency offset and a degree of certainty related to a detected direction (e.g., positive or negative) of the frequency offset. If the confidence number is greater than a threshold value, a joint frequency and phase lock loop (“FPLL”) is used for carrier acquisition. If the confidence number is less than the threshold value, a phase lock loop (“PLL”) is used for carrier acquisition. | 03-24-2011 |

20090262865 | CARRIER FREQUENCY OFFSET ESTIMATING DEVICE AND SYSTEM - A carrier frequency offset estimating device for estimating frequency offsets of a multi-carrier signal includes a transforming circuit, a cosine effect eliminating circuit, a model creating circuit, and an estimating circuit. The transforming circuit receives the multi-carrier signal and transforms the multi-carrier signal to single-carrier signals. The cosine effect eliminating circuit eliminates cosine effects in the single-carrier signals to form single-carrier signals without the cosine effects. The model creating circuit creates linear data models according to the single-carrier signals without the cosine effects. The estimating circuit estimates the frequency offsets of the multi-carrier signal according to the linear data models. A carrier frequency offset estimating system is also provided. | 10-22-2009 |

20080212717 | Carrier frequency detection for signal acquisition - A carrier frequency in a filtered received M-ary phase-shift keyed (MPSK) modulated signal having in-phase and quadrature components is detected by processing the filtered received signal to remove modulation components and thereby generate a test signal at the carrier frequency; processing the test signal to provide an amplitude spectrum of samples at different test frequencies; and processing the amplitude spectrum to detect the carrier frequency in accordance with the test frequency at which there is a test statistic of the highest magnitude. The magnitude of the test statistic is determined by processing a signal statistic in relation to a noise statistic. The signal statistic is the amplitude of the largest-amplitude sample. The filtered received signal is processed to provide approximate values of the modulus of the received signal and the phase of the received signal; and the approximate modulus and phase values are processed to generate the test signal. | 09-04-2008 |

20080240297 | DIGITAL BROADCASTING SYSTEM AND METHOD OF PROCESSING DATA - A digital broadcast receiving system includes a known data detector, a carrier recovery unit, and a timing recovery unit. The known data detector may detect known data information inserted and transmitted from a digital broadcast transmitting system and using the known data information to estimate initial frequency offset. The carrier recovery unit may obtain initial synchronization by using the initial frequency offset, and may detect frequency offset from the received data by using the known sequence position indicator so as to perform carrier recovery. The timing recovery unit may detect timing error information from the received signal by using the known sequence position indicator so as to perform timing recovery. | 10-02-2008 |

20080240296 | Iterative sequential carrier acquisition - A system and method for iterative sequential carrier acquisition for estimating and correcting large carrier frequency offsets without adding significantly to receiver complexity or preamble length. A coarse frequency estimation is performed during a brief carrier acquisition phase that is completed during a reasonably short preamble, and then the system hands frequency control to the nominal carrier frequency & phase tracking of a phase-locked loop (PLL) circuit. The present disclosure generally includes an initialization mode, a pre-lock scan mode, an iterative search mode and a termination mode. | 10-02-2008 |

20140307835 | CARRIER FREQUENCY AND PHASE RECOVERY IN QUADRATURE ENCODED E-BAND COMMUNICATIONS - A mechanism for retrieval of carrier frequency and carrier phase in a received modulated carrier waveform. Retrieval of carrier frequency and carrier phase can be implemented in an analog electrical circuit, using a field programmable gate array (FPGA), or in computer code. Independent of the implementation, the mechanism performs frequency and primary phase recovery by forcing transforms of a pilot tone in the upper and lower sidebands to the same frequency using a feedback loop. The difference-in-magnitudes of the channelized pilot are used by a phase lock loop to perform secondary phase recovery in a manner that also resolves phase sign ambiguity. Benefits of this mechanism include improved phase lock loop tracking performance and a reduction of noise in the data demodulated from the received carrier waveform. | 10-16-2014 |

20100215127 | METHOD FOR ESTIMATING A CARRIER-FREQUENCY SHIFT IN A TELECOMMUNICATION SIGNALS RECEIVER, NOTABLY A MOBILE DEVICE - This method for estimating a carrier-frequency offset (Δf) in a telecommunication signals receiver comprises the following steps: | 08-26-2010 |

20100215126 | CARRIER RECOVERY APPARATUS AND METHOD THEREOF - A carrier recovery apparatus includes a pilot strength detector, a first lock loop, a second lock loop, and a controller. The pilot strength detector determines whether a pilot strength of an input signal is greater than a threshold value to generate a control signal. The first lock loop performs a first carrier recovery on the input signal. The second lock loop performs a second carrier recovery on the input signal. The controller selectively allows the first lock loop to perform the first carrier recovery on the input signal or the second lock loop to perform the second carrier recovery on the input signal according to the control signal. The first lock loop is a pilot-based FPLL and the second locked loop is a pilot-less PLL. | 08-26-2010 |

20140254723 | POLAR MULTI-SYMBOL DELAY DETECTOR FOR CARRIER PHASE AND FREQUENCY RECOVERY FOR COHERENT TRANSMISSION - A method for calculating a reconstructed phase that includes: Calculating a current phase signal and current amplitude signal that represent a phase and amplitude of a current input symbol, respectively. Generating, in response to the current phase signal and an estimate of a phase of a last input symbol that preceded the current input symbol, multiple partial references, some of which are responsive to (i) phase signals representative of phases of a plurality of input symbols that preceded the current input symbol, and (ii) estimates of the phase of the plurality of input symbols. Calculating unwrapped partial references. Estimating a constant carrier frequency offset (CFO) phase rotation in response to the unwrapped partial references. Calculating a reconstructed phase of the current input symbol in response to, at least, the estimate of the constant CFO phase rotation and to the unwrapped partial references. | 09-11-2014 |

20100310014 | CARRIER RECOVERY DEVICE AND METHOD - A carrier recovery device and a carrier recovery method are provided. The device includes a phase detection module, a computation module, a phase angle adjustment module, a loop filter, and a conversion module. The phase detection module receives an IF signal, and detects a sine and a cosine signals corresponding to the IF signal. The computation module receives the sine and the cosine signals, and computes a phase angle between the sine and the cosine signals. The phase angle adjustment module adjusts the phase angle according to one of the sine and the cosine signals and a threshold. The loop filter generates a frequency offset angle according to the phase angle. The conversion module generates a sine and a cosine parameters according to the frequency offset angle, and transfers the sine and the cosine parameters to the phase detection module. | 12-09-2010 |

20110080978 | MULTI-STAGE FREQUENCY OFFSET ESTIMATION AND COMPENSATION METHOD AND ITS CIRCUIT - A multi-stage frequency offset (FO) estimation and compensation method and its circuit are described. The method includes performing at least a stage of primary-level FO estimation and compensation procedure, and a stage of advance-level FO estimation and compensation procedure. The first stage receives an input carrier signal of a larger FO and outputs a corrected carrier signal with an estimation error within the required estimation range of the next stage, to the next stage. Generated and fed forward stage-by-stage, the corrected carrier signal free of FO may be approached. Besides, since a feed-forward rather than a closed-loop approach is employed, the SNR requirement may be lower. Also, at primary-level, modulation may be first removed so the whole input carrier signal may be used to estimate FO; at advance-level, the periodic PN sequence in the input carrier signal may be utilized to estimate FO, thereby no dedicated training symbols are required. | 04-07-2011 |

20110075766 | DIGITAL BROADCASTING SYSTEM AND METHOD OF PROCESSING DATA - A digital broadcast receiving system includes a known data detector, a carrier recovery unit, and a timing recovery unit. The known data detector may detect known data information inserted and transmitted from a digital broadcast transmitting system and using the known data information to estimate initial frequency offset. The carrier recovery unit may obtain initial synchronization by using the initial frequency offset, and may detect frequency offset from the received data by using the known sequence position indicator so as to perform carrier recovery. The timing recovery unit may detect timing error information from the received signal by using the known sequence position indicator so as to perform timing recovery. | 03-31-2011 |

20100067619 | COMMUNICATIONS DEVICE USING MEASURED SIGNAL-TO-NOISE RATIO TO ADJUST PHASE AND FREQUENCY TRACKING - A communications device includes a phase and frequency tracking loop having a signal input and adjustable loop filter that establishes a predetermined tracking loop bandwidth for samples of communication signals received at the signal input and processed within the tracking loop. A tracking loop update circuit updates the loop filter operating parameters. It is operative with the loop filter for increasing or decreasing the tracking loop bandwidth of the phase and frequency tracking loop based on the measured signal-to-noise ratio in the received samples of communication signals at the signal output by the tracking loop and on the known or measured apriori tracking capabilities of demodulator based on the symbol rate of communication signal. | 03-18-2010 |

20090175385 | Tolerable Synchronization Circuit of RDS Receiver - A Radio Data System (RDS) decoder circuit determines a subcarrier frequency utilizing only a 57 kHz RDS signal of an FM broadcast signal. The RDS decoder includes a zero-intermediate frequency (zero-IF) FM demodulator, a first mixer, a low-pass filter (LPF) unit, a shaping filter unit, a carrier recovery circuit, a digitally controlled oscillator (DCO), a symbol timing recovery circuit, an integrate and dump circuit, a slicer | 07-09-2009 |

20110069788 | METHOD AND SYSTEM FOR TRACKING PHASE IN A RECEIVER FOR 8VSB - Embodiments of the invention relate to systems and methods for tracking phase in a receiver which uses multiple phase tracking techniques. A phase tracking module generates a plurality of symbol decisions related to received 8-level-vestigial-sideband (“8VSB”) signals, determines a phase tracking threshold value based on a mean square error, receives an estimated imaginary component of a transmitted signal based on the symbol decisions, and determines a phase estimate based on the imaginary component of the transmitted signal and the plurality of symbol decisions. The phase tracking module selects one of a first phase tracking technique and a second phase tracking technique based on the phase estimate. The first phase tracking technique is selected when the phase estimate is greater than the phase tracking threshold value, and the second phase tracking technique is selected when the phase estimate is less than the phase tracking threshold value. | 03-24-2011 |

20120224657 | CARRIER RECOVERY CIRCUIT AND DEMODULATION CIRCUIT UNDER QUASI-COHERENT DETECTION METHOD - A carrier recovery circuit, adapted to a demodulation circuit according to a quasi-coherent detection method for generating baseband signals by way of quadrature detection on a received signal having an intermediate frequency, rotates phases of baseband signals; detects a phase error and an amplitude error; controls a bandwidth of a loop filter based on its difference, eliminates a high-frequency component from the phase error; and performs phase rotation based on the phase error eliminating its high-frequency component. It expands the bandwidth of the loop filter when a difference between the phase error and the amplitude error is greater than a predetermined threshold, whilst reducing bandwidth of the loop filter upon determining that the amplitude error decreases due to a reduction of the bandwidth of the loop filter. This optimizes the bandwidth of the loop filter to follow variations of the C/N ratio of the received signal, improving bit error rate. | 09-06-2012 |

20080298510 | Memory-Saving Method for Generating Soft Bit Values from an OFDM Signal - Methods and receiver circuits for determining and employing decision boundary estimates for use in de-mapping QAM symbols in an OFDM receiver are disclosed. The disclosed methods efficiently use memory resources, while taking account of the frequency-selective and time-varying nature of the signal propagation. An OFDM receiver calculates a decision boundary estimate using QAM-modulated symbols selected from a group of OFDM tones and determines soft bit values for symbols selected from an adjacent tone using the decision boundary estimate. The receiver updates the decision boundary estimate using the symbols from the adjacent tone and determines soft bit values for symbols selected from a next-adjacent tone using the updated decision boundary estimate. Once the decision boundary estimate has been updated and the soft bit values have been determined for each tone, the symbol data for that tone may be discarded. | 12-04-2008 |

20090129509 | DIGITAL BROADCASTING SYSTEM AND DATA PROCESSING METHOD - A receiving system and data processing method therein are disclosed, by which mobile service data is received and processed. The receiving system comprises a tuner, a filter, an IQ mismatch processor, a gain controller and a demodulator. The tuner tunes radio frequency (RF) signals of a specific channel which includes mobile service data and main service data, converts the tuned RF signals into zero IF signals and outputs the converted zero IF signals. The filter performs low pass filtering for the zero IF signals output from the tuner. The IQ mismatch processor estimates and compensates IQ mismatch generated in the zero IF signals filtered by the filter. The gain controller controls gain of the zero IF signals by estimating a gain error of the zero IF signals output from the IQ mismatch processor. The demodulator performs carrier recovery and timing recovery by receiving the zero IF signals output from the gain controller. | 05-21-2009 |

20080219383 | Method and Apparatus for Carrier Recovery Using Multiple Sources - In a receiver, a decision-directed phase estimator is used in conjunction with an interpolator to provide a phase estimate for use in carrier recovery. For example, a receiver comprises a pilot phase estimator, a Costas loop and an interpolation controller. The pilot phase estimator provides determined phase estimates at the pilot times and the interpolation controller provides interpolated phase estimates at other times as a function of a linear interpolation based on a respective determined phase estimate and at least one decision-directed phase error estimate from the Costas loop. | 09-11-2008 |

20100061488 | JOINT, ADAPTIVE CONTROL OF EQUALIZATION, SYNCHRONIZATION, AND GAIN IN A DIGITAL COMMUNICATIONS RECEIVER - Various aspects and embodiments of the present invention derive statistics of received signal quality and use these statistics to jointly control operation of timing recovery, carrier recovery, automatic gain control, and equalization functions. | 03-11-2010 |

20120300881 | RECEIVING APPARATUS - A receiving apparatus includes a correlation operation unit and a determination unit. The correlation operation unit is configured to perform a correlation operation with a known signal on a received signal including the known signal in a predetermined interval. The determination unit is configured to determine whether or not a correlation peak interval detected by the correlation operation unit deviates from the predetermined interval. | 11-29-2012 |

20090220029 | CLOCK RECOVERY CIRCUIT AND DATA RECEIVING CIRCUIT - A clock recovery circuit has a boundary detection circuit detecting a boundary in an input signal in accordance with a first signal, and performs recovery of a clock by controlling the timing of the first signal in accordance with the detected boundary. The clock recovery circuit has a boundary detection timing varying circuit and a variation reducing circuit. The boundary detection timing varying circuit dynamically varies boundary detection timing in the boundary detection circuit by applying a variation to the first signal, and the variation reducing circuit reduces a phase variation occurring in the recovered clock in accordance with the dynamic variation of the boundary detection timing performed by the boundary detection timing varying circuit. | 09-03-2009 |

20120314814 | PHASE OFFSET COMPENSATOR - A phase offset compensator for compensating a phase offset is provided. The phase offset includes a first phase sub-offset and a second phase sub-offset. The phase offset compensator includes a feedback loop comprising a first loop filter, the feedback loop being configured to compensate the first phase sub-offset of the phase offset, and a feed forward loop comprising a second loop filter, the feed forward loop being configured to compensate the second phase sub-offset of the phase offset. | 12-13-2012 |

20080225990 | APPARATUS AND METHOD FOR SIGNAL PHASE CONTROL IN AN INTEGRATED RADIO CIRCUIT - An apparatus and method to control signal phase in a radio device includes a phase rotator configured to control a phase of a local oscillator. A phase error determination module is configured to determine phase error information based on received in-phase (I) and quadrature (Q) (IQ) signal values. A phase correction module is configured to derive from the received IQ signal values a correction signal and apply the correction signal to the phase rotator in a path of the local oscillator. | 09-18-2008 |

20080225989 | High speed multi-modulus prescalar divider - A system and method are provided for multi-modulus division. The method accepts an input first signal having a first frequency and divides the first frequency by an integral number. A second signal is generated with a plurality of phase outputs, each having a second frequency. Using a daisy-chain register controller, phase outputs are selected and supplied as a third signal with a frequency. Selecting phase outputs using the daisy-chain register controller includes supplying the third signal as a clock signal to registers having outputs connected in a daisy-chain. Then, a sequence of register output pulses is generated in response to the clock signals, and register output pulses are chosen from the sequence to select second signal phase outputs. By using 8-second signal phase outputs, a third signal is obtained with a frequency equal to the second frequency multiplied by one of the following numbers: 0.75, 0.875, 1, 1.125, or 1.25. | 09-18-2008 |

20140023162 | Method and System for An OFDM Joint Training and Frequency Tracking System - Aspects of a method and system for an OFDM joint timing and frequency tracking system may include tracking carrier frequency and symbol timing in an Orthogonal Frequency Division Multiplexing (OFDM) signal based on at least a reference symbol set. A receiver frequency and timing may be adjusted based on the tracked carrier frequency and symbol timing. The carrier frequency may be tracked by generating an output signal as a function of a frequency offset Δf, and the symbol timing may be tracked by generating an output signal as a function of a guard time Δt | 01-23-2014 |

20130329834 | Feed-Forward Carrier Phase Recovery for Optical Communications - The carrier phase of a carrier wave modulated with information symbols is recovered with a multi-stage, feed-forward carrier phase recovery method. A series of digital signals corresponding to the information signals is received. For each digital signal, a coarse phase recovery is performed to determine a first phase angle which provides a first best estimate of the information symbol corresponding to the digital signal. Using the first best estimate as input, a second stage of estimation is then performed to determine a second phase angle which provides an improved (second) best estimate of the information symbol. Additional stages of estimation can be performed. The multi-stage, feed-forward carrier phase recovery method retains the same linewidth tolerance as a single-stage full blind phase search method; however, the required computational power is substantially reduced. The multi-stage, feed-forward carrier phase recovery method is highly efficient for M-QAM optical signals. | 12-12-2013 |

20140241466 | LOW SYMBOL RATE RAPID CARRIER ACQUISITION WITH EXTREMELY LARGE FREQUENCY OFFSET FOR DIGITAL COMMUNICATION RECEIVER - A method of rapid non-data aided carrier signal acquisition for a low symbol rate carrier signal, comprising receiving and converting an analog intermediate frequency carrier to a digital carrier signal, down-converting the signal to substantially baseband, reducing a sampling rate of the digital carrier signal using a decimation filter, determining a highest Fast Fourier Transform (FFT) based on a result of one or more FFT's generated by an FFT module using a peak finder, selecting an input source for the FFT module using a multiplexer, generating a frequency estimate of the digital carrier signal using a walking coarse detector, tuning a carrier recovery loop (CRL) based on the frequency estimate generated by the walking coarse detector, determining a final carrier frequency offset estimate using a result of the FFT module, modulation removal, and the peak finder, and programming an oscillator within the CRL to the final carrier frequency offset estimate. | 08-28-2014 |