692 results about "Amplitude modulation" patented technology

The invention relates to the technical field of mechanical fault diagnosis, and discloses a gearbox fault diagnosis method and system based on lightweight variational Bayesian learning, and the method comprises the steps: collecting a to-be-diagnosed vibration signal of a gearbox, carrying out the preprocessing of the to-be-diagnosed vibration signal, and obtaining an original vibration signal and the fault feature frequency of the original vibration signal; determining amplitude modulation-frequency modulation sparse combination representation of the original vibration signal according to the fault characteristic frequency of the original vibration signal, and constructing a joint probability model according to classification distribution containing sparse vectors and the amplitude modulation-frequency modulation sparse combination representation of the original vibration signal; performing variational Bayesian inference solution on the joint probability model by using the non-overlapping sub-sequence of the original vibration signal and natural gradient optimization to obtain posterior probability estimation of a sparse coefficient; and determining an activation component according to the posterior probability estimation of the sparse coefficient and the sparse precision parameter, and matching the activation component with a pre-established multi-scale amplitude modulation-frequency modulation sparse dictionary to obtain a fault type and a confidence coefficient thereof.

The invention discloses a multi-scattering SAR (Synthetic Aperture Radar) imaging simulation method, system and device based on physical consistency modeling and a medium. The method comprises the following steps: constructing a three-dimensional electromagnetic model of a target; constructing a geometric model under the working mode of the ray tracing auxiliary transmitting-receiving co-located SAR; a high-frequency electromagnetic scattering algorithm based on ray tracing is adopted, multiple scattering paths of a first order, a second order and a higher order are considered, superposition and amplitude modulation are carried out on scattering contributions of all orders, scattering field distribution of a target under the far field condition is calculated, and a far-field scattering field is obtained; performing spatial propagation mapping on the total far-field scattering field, and mapping a far-field scattering result into a radar platform near-field echo signal; correcting the amplitude of the echo signal to obtain a two-dimensional SAR near-field echo matrix; sAR imaging processing is carried out, wherein the SAR imaging processing comprises distance compression, range migration correction (RCMC) and azimuth compression. According to the invention, the authenticity and precision of SAR imaging simulation in a complex target scene are improved.

The invention relates to a display device. The display device comprises a light-emitting device and a pixel circuit. The pixel circuit comprises an amplitude modulation module, a pulse width modulation module and a switch module. A first capacitor in the pulse width modulation module is used for storing a first electric charge quantity corresponding to a pulse width data signal received by the pulse width modulation module. And a second capacitor in the amplitude modulation module is used for storing a second electric charge quantity corresponding to the amplitude data signal received by the driving unit. A connection node of the first capacitor and the driving unit is a first node, a connection node of the second capacitor and the pulse width control unit is a second node, and the switch module is connected between the first node and the second node and used for conducting the first node and the second node before a reset stage so as to neutralize charges stored in the first capacitor and the second capacitor. Therefore, the voltage of the first node is reduced, the influence on the reset signal is reduced, the problem that the light-emitting device emits light abnormally in the reset stage is solved, and the display effect of the display device is improved.

The present invention discloses an unified multiple access (MA) based system for uplink transmission of data by multiple users. The system comprises an user interface integrated transmitter modules for transmitting the data from multiple user transmitters over waveforms through a cooperative unified data grid structure including grid points, said unified data grid structure including each user transmitter allocation of a few non-overlapping grid points for loading respective data bearing symbols, with zeros loaded onto unallocated grid points. The user transmitter is configured to transmit a sparsely loaded grid resembling to the unified two-dimensional data grid structure involving data-bearing Quadrature Amplitude Modulation (QAM), where a part of available grid points of the grid as allocated is loaded with QAM symbols and remaining grid points are loaded with zero symbols. A waveform modulator corresponding to user transmitter is also provided in the present system for waveform modulation of said sparsely loaded grid as per the waveforms enabling transmission for multi-antenna reception of the waveforms to a base station or an access point.

The invention relates to the technical field of gear detection, in particular to a gear wear detection method and system of a gear motor. According to the method, firstly, all fault characteristic frequencies are obtained based on historical vibration signals of a fault gear, then vibration signals of a to-be-detected gear are divided into a plurality of local impact sub-segments, and the local frequency spectrum of each local impact sub-segment and the kurtosis of each frequency in the local frequency spectrum are obtained; fitting a fuzzy estimation signal of the vibration signal in combination with power distribution under each fault characteristic frequency in the time-frequency spectrum, and then modulating the vibration signal in combination with a motor load condition; and finally analyzing a frequency spectrum signal of the modulation vibration signal, and evaluating the early wear type of the gear to be detected. According to the method, the vibration signal is modulated by analyzing the covering interference of noise and motor load on local wear impact, and the frequency modulation effect and the amplitude modulation effect are further analyzed in the frequency domain of the modulated vibration signal, so that the early wear type is accurately distinguished, and the gear wear detection effect is improved.

The invention relates to a method and a system for realizing fast and uniform focusing of emergent light spots of a multi-mode optical fiber based on superpixels, belongs to the technical field of novel optical imaging and light field regulation and control, and integrates online speckle acquisition, offline amplitude optimization and an online speckle acquisition stage. When a certain modulation area is in an activated state, respectively capturing a non-interference speckle image of the emergent end of the multimode optical fiber and an interference speckle image generated when the area and the reference area are activated at the same time, and traversing all the modulation areas to totally obtain a speckle image; in the off-line amplitude optimization stage, a focusing light spot is preset, and calculation is carried out by utilizing intensity information of a corresponding focusing position in the speckle image. And analyzing all the focusing light spots one by one so as to construct a binary amplitude modulation mask. And the masks are loaded to the spatial light modulator one by one, so that accurate point-by-point focusing of N emergent light spots of the multimode optical fiber is realized, and the focusing efficiency and uniformity are greatly improved.

An aerosol provision device or a vapor provision device including an aerosol generator or vapor generator; a driving circuit connected to the aerosol generator or vapor generator, wherein the driving circuit is configured to employ either pulse width modulation or amplitude modulation, to supply power to the aerosol generator or vapor generator; and a power source connected to the driving circuit, wherein the power source includes a hybrid ion capacitor.

The invention discloses a three-degree-of-freedom ultrasonic motor driving control method. A three-degree-of-freedom ultrasonic motor comprises a signal generation module, a key control module, a power amplification module, a communication module, a grating ruler analysis module, a control algorithm, a data processing module, a power amplification circuit, a matching circuit and a voltage and current sampling circuit. The signal generation module outputs six paths of PWM waves with adjustable frequencies, phases and duty ratios, the control algorithm module performs adjustment through a control algorithm according to operation parameters of an ultrasonic motor fed back by a grating ruler, the key module is used for manual control, and the communication module is composed of USART logic and DMA logic. A control algorithm and data processing are generated by a single-chip microcomputer, detection and servo control are carried out through a communication USART module, and real-time monitoring, power amplification and matching are carried out on a serial port assistant of an upper computer, and a voltage and current sampling circuit drives and stabilizes operation of the ultrasonic motor. According to the invention, the amplitude modulation precision is below 4mv, and the stability is higher through a closed-loop control algorithm.

The invention discloses a diamond low-frequency current measurement method with nonlinear response to magnetic field intensity, which is characterized in that two coils are wound on a magnetic flux collector with a communicated structure, a high-frequency (800Hz) high-voltage (7V) driving current is injected into one of the coils, a magnetic field generated by the coil is amplified through the magnetic flux collector and guided to an area where an NV color center magnetometer is located, and the NV color center magnetometer is located; and the signal is driven to enter a nonlinear response interval in the demodulated ODMR spectrum. A weak (1-50mV) to-be-measured low-frequency (0.1-10Hz) current signal is injected into the other coil, amplitude modulation is performed on the weak (1-50mV) to-be-measured low-frequency (0.1-10Hz) current signal by using the same frequency as the driving current, and the weak (1-50mV) to-be-measured low-frequency (0.1-10Hz) current signal is amplified by the magnetic flux collector and guided to the NV The microwave frequency is locked at the maximum slope point of the ODMR frequency spectrum through CW-ODMR phase-locked amplification, so that the relationship between the change of the red fluorescence signal intensity and the size of the external magnetic field is obtained, and the signal intensity of the low-frequency current magnetic field to be measured is measured according to the relationship.

The invention discloses an intermediate frequency electro-therapeutic apparatus, which comprises a controller and a waveform synthesis circuit, and is characterized in that the waveform synthesis circuit comprises a first amplitude adjusting circuit, a second amplitude adjusting circuit and a synthesis adjusting circuit, and the controller generates a first PWM signal according to the overall amplitude information; the first amplitude adjusting circuit performs amplitude modulation processing on an input original waveform according to the first PWM signal to generate a first analog waveform signal; the controller obtains amplitude information corresponding to the frequency of the modulation waveform by using the phase accumulator, and generates a second PWM signal; a second amplitude adjusting circuit performs multiplication operation on the second PWM signal and the first analog waveform signal to obtain a second analog waveform signal and obtain an inverted waveform signal; the controller obtains amplitude information corresponding to the frequency of the fundamental frequency waveform by using a phase accumulator, and generates a third PWM signal; and the synthesis adjusting circuit performs multiplication operation on the third PWM signal and the second analog waveform signal or the inverted waveform signal to generate an intermediate frequency treatment waveform.

The invention discloses an ODAC implementation system and method based on a five-segment thermo-optical phase modulator, and relates to the technical field of optical communication, and the method comprises the following steps: obtaining single-mode laser input, dividing the single-mode laser input into two paths through a multi-mode interference device beam splitter, and transmitting the single-mode laser input into an upper arm and a lower arm of a Mach-Zehnder modulator; the current is adjusted through the thermo-optic phase modulator to control the temperature, the refractive index is changed to introduce phase delay, and the phase difference of two arms of the Mach-Zehnder modulator is calibrated; on the basis of a five-segment thermo-optical modulator, hierarchical amplitude modulation is carried out on beam splitting light according to digital input, a phase space is constructed by utilizing weight combination, and a linear optimal discrete state is screened; the modulated light is combined by a multi-mode interference device beam combiner, and digital-analog mapping output of light intensity is carried out; a detector installed at an output port of the five-segment thermo-optical phase modulator is used for monitoring output optical power in real time, the output optical power is fed back to a control circuit to calculate errors, thermo-optical modulation current is dynamically adjusted to compensate offset point drift, and optical digital analog conversion is achieved.

The invention discloses a low-sidelobe antenna based on double-metasurface amplitude and phase independent regulation and control. The antenna structure comprises a metasurface 1 and a metasurface 2. The metasurface 1 and the metasurface 2 comprise a plurality of metasurface units; the metasurface 1 is a phase modulation plane, comprises a phase regulation and control unit and is decoupled with the amplitude control function of the amplitude filtering plane; the metasurface 2 is an amplitude filtering plane and comprises an amplitude regulation and control unit, and the modulation process is decoupled from phase regulation and control of the metasurface 1; the phase regulation and control unit and the amplitude regulation and control unit comprise three metal layers and two dielectric layers; the first layer, the third layer and the fifth layer from bottom to top are metal layers, and the second layer and the fourth layer are dielectric layers. Through the design of the double-layer metasurface structure, completely independent operation of the phase regulation and control layer and the amplitude modulation layer is achieved, the technical contradiction that amplitude and phase parameters in a traditional single-layer metasurface are mutually restrained is avoided, and the core technical problem that the side lobe level of a transmission antenna is too high is solved cooperatively.

Systems and devices are provided for receiving or transmitting IQ data (e.g., suitable for passband quadrature amplitude modulation (QAM)) over a wireline using pairs of baseband pulse amplitude modulation (PAM-n) signals. Encoding circuitry may map data from an input bit stream to IQ data that includes an in-phase component and a quadrature-phase component. Modulator circuitry may determine an in-phase PAM-n signal based on the in-phase component and a quadrature-phase PAM-n signal based on the quadrature-phase component. Driver circuitry may transmit the in-phase PAM-n signal and the quadrature-phase PAM-n signal across a wireline channel. The in-phase PAM-n signal may be different by 90° from the quadrature-phase PAM-n signal. This may enable a remote receiver on the wireline channel to detect the in-phase PAM-n signal independently of the quadrature-phase PAM-n signal.

An optical frequency generation system (100), comprising: - reference atoms (7) in a gas phase, - an interrogation laser source (1) configured to emit an interrogation signal (101) comprising a first optical frequency suitable for exciting a two-photon transition in said reference atoms (7), said interrogation signal (101) being configured to interact with said reference atoms (7) in a Doppler-free scheme; - optical frequency modulation means (31, 31a, 31b) configured to adjust said first optical frequency and to modulate said first optical frequency at a first modulation frequency f1; - an optical sensor (9) configured to detect a fluorescence signal (110) from said reference atoms (7); - a first control loop (10) configured to lock said first optical frequency to a resonance frequency of said two-photon transition, said fluorescence signal (110) being input into the first control loop (10); - a mitigation laser source (2) configured to emit a mitigation signal (102) comprising a second optical frequency selected to produce a light-shift of said two-photon transition of opposite sign of the light-shift produced by the interrogation signal (101); characterized in that the optical frequency generation system (100) further comprises: - optical amplitude modulation means (5) configured to modulate the amplitude of the interrogation signal (101) and of the mitigation signal (102) at a second modulation frequency f2, and - a second control loop (20) configured to adjust the relative amplitude of the mitigation signal (102) with respect to the interrogation signal (101) such as to cancel the effective light-shift of the combined interrogation (101) and mitigation (102) signals.

Metamaterial optics are integrated with vacuum-boundary walls of ultra-high-vacuum (UHV) cells to manipulate light in a manner analogous to various bulk optical elements including lenses, mirrors, beam splitters, polarizers, waveplate, wave guides, frequency modulators, and amplitude modulators. For example, UHV cells can have metasurface lenses formed on interior and / or exterior surfaces on one or more of their vacuum-boundary walls. Each metasurface lens can include a plurality of mesas with the same height and various cross-sectional dimensions. The uses of metasurface lenses allows through-going laser beams to be expanded, collimated or focused without using bulky refractive optics. Each metasurface lens can be formed on a cell wall using photolithographic or other techniques.

The invention discloses a sine frequency modulation harmonic error compensation method based on Bessel function modulation characteristics, and relates to the technical field of sine frequency modulation nonlinear parameter compensation and high-precision measurement of target absolute distance based on multi-wavelength interference. The problem that the constant phase demodulation precision is insufficient due to the fact that carrier harmonic waves, accompanying amplitude modulation and modulation depth errors cannot be effectively suppressed due to laser modulation nonlinearity in existing sine frequency modulation distance measurement is solved. According to the method, after sine frequency modulation interference signals are collected, high-pass filtering is carried out to remove low-frequency components, Hilbert transform is carried out to remove envelope suppression associated amplitude modulation, window function frequency mixing is carried out to extract modulation depth, a matched carrier containing second harmonics is constructed, and frequency modulation harmonic parameter optimization is achieved through baseband amplitude maximization. And finally, carrying out orthogonal demodulation on the compensated interference signal to obtain a high-precision constant phase. The method is suitable for high-precision multi-wavelength interference ranging, precision displacement measurement and optical metering systems.

An enhanced link adaptation (eELA) method includes receiving, by a responding device from a requesting device, a physical layer protocol data unit (PPDU) including an eELA request message, determining, by the responding device, an eELA feedback message comprising unequal quadrature amplitude modulation (UEQM) information across a plurality of spatial streams based on at least the number of spatial streams derived from the eELA request message or the PPDU, and transmitting, from the responding device to the requesting device, the eELA feedback message. The UEQM information indicates an effective Signal-to-Noise Ratio (SNR) per spatial stream or a derivative of the effective SNR per spatial stream.

The invention belongs to the technical field of computer vision and computer graphics, and discloses a multi-view three-dimensional reconstruction method and device based on cross-domain feature fusion and a medium, and the method comprises the steps: carrying out the cross-feature-domain coding of an initial feature token generated by a multi-view image, according to the coding, characteristics are decomposed into low-frequency components and high-frequency components through dual-tree complex wavelet transform, amplitude modulation is carried out on the high-frequency components to enhance details, and space-frequency fusion characteristics are generated; variance embedding weighted combination is carried out on the multi-view space-frequency fusion features, the combination generates a weight by calculating the variance of each feature token, adaptive weighted clustering is carried out based on the weight, and fused multi-view features are generated; and performing three-source attention decoding on the fused features, and performing cross-domain attention calculation and up-sampling by taking static embedding as query, taking the space-frequency fused features as keys and taking the fused multi-view features as values, thereby finally generating a three-dimensional voxel reconstruction result of the target object.

The invention belongs to the technical field of power equipment fault diagnosis, and particularly discloses a knowledge distillation-based 1D-CNN online partial discharge identification method, which comprises the following steps of performing Fourier transform on an original signal and then implementing four data enhancements of amplitude modulation, phase modulation, frequency band enhancement and frequency domain noise injection; constructing a multi-branch one-dimensional convolutional neural network to extract time-frequency features, and training a teacher model in combination with residual connection and an SE attention mechanism; compressing the teacher model into a lightweight student model by adopting a knowledge distillation strategy of a preset temperature parameter and a weight coefficient; the student model is converted into a mobile terminal compatible format, and a mobile phone APP is established through a QT upper computer; and online real-time identification is realized. According to the method, the problem of sample imbalance is effectively relieved, in addition, the knowledge distillation realizes model volume compression and reasoning speed increase while keeping relatively high accuracy, the calculated amount is small, the real-time performance is high, and the precision is high.

The invention discloses a hollow-core optical fiber communication method and system for reducing complexity, and the method comprises the steps: obtaining original bit data, and mapping the original bit data to an initial constellation diagram through a quadrature amplitude modulation mapping algorithm; rotating the initial constellation diagram according to a preset rotation angle to obtain a first constellation optimization diagram, adjusting the first constellation optimization diagram by using a sparrow search algorithm to obtain a second constellation optimization diagram, converting the second constellation optimization diagram into a transmission signal, and transmitting the transmission signal to the receiving end through a hollow-core optical fiber; performing data preprocessing on the received transmission signal to obtain a de-noised signal, performing phase recovery on the de-noised signal based on a quadratic algorithm to obtain a second constellation optimization graph, and performing de-mapping on the second constellation optimization graph to re-convert the second constellation optimization graph into original bit data; according to the invention, the complexity of digital signal processing is reduced, and the accuracy and efficiency of phase recovery are obviously improved, so that the performance of a coherent optical communication system based on the hollow-core optical fiber is comprehensively improved.

A diamond magneto-optical sensor includes: a diamond that includes a color center with an electronic spin and is irradiated with excitation light, and an irradiation unit that irradiates the diamond with the excitation light of the color center and electromagnetic waves for magnetic resonance, wherein the irradiation unit receives modulated light having been subjected to amplitude modulation, and a modulation frequency of the modulated light is included in a microwave frequency band.

An apparatus may include a transmitter and one or more processors configured to identify a code rate of a low-density parity-check (LDPC) code, receive, by an LDPC encoder, a set of information bits and encode, using the code rate, the set of information bits to generate a set of encoded bits and a set of parity bits, generate, from the set of encoded bits, a matrix of bit arrays, discard one or more parity bits from the set of parity bits to generate a parity bit array with a size equal to a number of column of the matrix, generate a bit array by concatenating (1) one or more bit arrays selected from the matrix of bit arrays and (2) one or more bits selected from the parity bit array corresponding to the one or more bit arrays, and modulate, by a modulator, the bit array to generate modulated data.

The invention provides a gear continuous spectrum vibration signal identification method based on EMD (Empirical Mode Decomposition) and HHT (Hilbert-Huang Transform), and belongs to the field of signal processing of mechanical power. The method comprises the following steps: acquiring an original vibration signal; performing FFT (Fast Fourier Transform) on the original vibration signal to obtain an amplitude spectrum; eMD decomposition is carried out on the original vibration signal to obtain a plurality of IMF components and a residual component; performing HHT (Hilbert-Huang Transform) on each IMF component to obtain an analytic signal, extracting an instantaneous amplitude and an instantaneous phase of the analytic signal, and calculating an instantaneous frequency according to the instantaneous phase; performing FFT (Fast Fourier Transform) on the instantaneous amplitude to obtain amplitude modulation information; performing FFT (Fast Fourier Transform) on the instantaneous frequency to obtain frequency modulation information; overlapping the amplitude modulation information and the frequency modulation information of each IMF component to generate a Hilbert envelope spectrum; and carrying out peak value labeling on each Hilbert envelope spectrum, and comparing the Hilbert envelope spectrums with the amplitude spectrums to finish the characteristic frequency identification of the gear vibration signals. According to the method, the problem that a traditional fast Fourier transform (FFT) method is insufficient in complex modulation signal analysis capacity is solved.

The invention discloses a four-dimensional antenna array multi-beam forming method based on amplitude-phase joint baseband modulation. A basic system is composed of a baseband signal source, a time sequence control system, a local oscillator source, a frequency mixer, a power divider, an amplitude-phase modulation switch, a filter, an amplifier, an antenna unit and radio frequency cables connecting all the parts. Through cooperative regulation and control of heterogeneous degrees of freedom of a digital baseband and an analog radio frequency domain, a joint optimization system of degrees of freedom of a digital domain baseband and time modulation dimensions of an analog domain is innovatively constructed, and an omni-directional reconfigurable multi-beam radiation pattern is realized. The antenna array has higher radiation efficiency by using phase modulation, and the sidelobe level of multiple beams is regulated and controlled by amplitude modulation weighting, so that the mutual interference among multiple beams and multiple signals is reduced, and the overall transmission performance is improved.

The invention discloses a motor fault diagnosis method and a motor controller. The method comprises the following steps: acquiring a near-field electromagnetic noise audio signal and a vibration acceleration signal of a motor shell when a motor runs; performing short-time Fourier transform on the near-field electromagnetic noise audio signal, and extracting an original electromagnetic voiceprint feature vector representing an internal electromagnetic state of the motor; the vibration acceleration signal is used as a modulation source, amplitude modulation processing is carried out on the original electromagnetic voiceprint feature vector, and a modulated electromagnetic voiceprint feature vector is generated; performing time domain coherence calculation on the original electromagnetic voiceprint feature vector and the modulated electromagnetic voiceprint feature vector to generate a two-dimensional electromagnetic-mechanical voiceprint interference map; and inputting the electromagnetic-mechanical voiceprint interference atlas into a convolutional neural network CNN, and outputting a final motor fault diagnosis result. According to the embodiment of the invention, the method can improve the discrimination of fault features, and achieves the high-precision diagnosis of motor faults under a complex working condition.

Disclosed is a method comprising, by a transmitter apparatus, partitioning (901) an input data stream to obtain a bit stream X1 and a bit stream X2; subjecting (902) the bit stream X2 to encoding by LDPC encoders, to obtain X2 parity bits, and X2 information bits; applying (903) SPC encoding to the X2 parity bits, together with the bit stream X1, to obtain sign bits, wherein the bit stream X1 is used as padding bits; subjecting (904) the sign bits, the padding bits, and the X2 information bits, to an interleaver operation to obtain an interleaver output; subjecting (905) the interleaver output to Gray mapping to form multiple consecutive quadratic amplitude modulation, QAM, symbols; modulating (905) the QAM symbols by quadratic amplitude modulation to obtain a modulated data stream; and transmitting (906) the modulated data stream via a radio access network or optical fibre communication network.

The invention discloses a time domain signal reproduction conversion method and device of an impact response spectrum and a medium. Belongs to the field of impact mechanical environment related design and test, and particularly belongs to the technical field of time domain signal reproduction of an impact response spectrum. The technical problem that the real time domain energy distribution condition of the time domain waveform corresponding to the impact response spectrum cannot be fully reflected in the prior art is solved. In the fundamental wave amplitude modulation, a Weibull sine window is adopted to process sine wavelets, and the time domain peak position and the decay time can be adjusted by utilizing the characteristic that a Weibull distribution function curve can change according to parameter adjustment. And waveform adjustment is realized by using a sine function, and the low-error convergence capability of the time domain waveform impact response spectrum is improved. Error control of the impact response spectrum of the reproduced time domain signal and the target impact response spectrum is superior to + / -2dB, parameterization control is carried out on the time domain waveform peak position and the decay time, and the distribution condition of impact energy under the time domain and frequency domain conditions is effectively reproduced.

In one aspect, a method described herein can be used for laser carrier recovery in optical coherent communication systems utilizing quadrature amplitude modulation (QAM) at a receiver. The method includes receiving, at the receiver, a transmitted signal modulated using QAM and a local oscillator (LO) signal. The method includes detecting, at the receiver, a phase offset between the transmitted signal and the LO signal. The method includes compensating, at the receiver, by generating an error signal based on the average power and / or voltage difference between the In-phase (I) and Quadrature-phase (Q) paths of the received signal at the receiver, where the error signal compensates for the phase offset between the transmitted signal and the LO signal.

A pulse amplitude modulation 4-level (PAM-4) physical layer (PHY) serializer / deserializer (SerDes) receiver is provided. The receiver may include an analog-front-end (AFE) block to receive a transmit signal, an analog-to-digital converter (ADC) block to convert the transmit signal into a digital signal at sampling intervals defined by a sampling clock signal, a clock and data recovery (CDR) circuit to receive the digital signal from the ADC block and extract a recovered clock signal and a recovered data stream, the recovered data stream containing a sequence of symbols with amplitude values corresponding to four levels of PAM-4, a phase integrator (PI) to generate the sampling clock signal for the ADC block based on the recovered clock signal, and a feedforward phase correction (FFPC) block to receive the recovered data stream and generate a receive signal.

DFT spreading is applied to a sequence of symbols to generate a DFT-spread sequence of symbols. The DFT-spread sequence of symbols is frequency-division multiplexed with a reference signal sequence to generate a multiplexed sequence, and the DFT-spread sequence of symbols and the reference signal sequence are recoverable from demultiplexing the multiplexed sequence. Further processing, such as a transform to convert to time domain and / or spectral shaping, may be applied in some embodiments. The symbols may be modulation symbols to which data bits are mapped, in binary phase-shift keying (BPSK) modulation, pi / 2-BPSK modulation, quadrature phase-shift keying (QPSK) modulation, quadrature amplitude modulation (QAM) or offset-QAM (OQAM), for example. Embodiments may be applied in conjunction with any of different types of reference signals, such as a demodulation reference signal (DM-RS), a phase tracking reference signal (PT-RS), or a channel state information reference signal (CSI-RS), or different types of reference signal sequences.