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High-Precision Doppler Frequency Estimation Based Positioning Using OTFS Modulations by Red and Blue Frequency Shift Discriminator 认领 引用 被引量：6
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作者 Shaojing Wang Xiaomei Tang +3 位作者 Jing Lei Chunjiang Ma Chao Wen Guangfu Sun 《China Communications》 SCIE CSCD 2024年第2期17-31,共15页
Orthogonal Time Frequency and Space(OTFS) modulation is expected to provide high-speed and ultra-reliable communications for emerging mobile applications, including low-orbit satellite communications. Using the Dopple... Orthogonal Time Frequency and Space(OTFS) modulation is expected to provide high-speed and ultra-reliable communications for emerging mobile applications, including low-orbit satellite communications. Using the Doppler frequency for positioning is a promising research direction on communication and navigation integration. To tackle the high Doppler frequency and low signal-to-noise ratio(SNR) in satellite communication, this paper proposes a Red and Blue Frequency Shift Discriminator(RBFSD) based on the pseudo-noise(PN) sequence.The paper derives that the cross-correlation function on the Doppler domain exhibits the characteristic of a Sinc function. Therefore, it applies modulation onto the Delay-Doppler domain using PN sequence and adjusts Doppler frequency estimation by red-shifting or blue-shifting. Simulation results show that the performance of Doppler frequency estimation is close to the Cramér-Rao Lower Bound when the SNR is greater than -15dB. The proposed algorithm is about 1/D times less complex than the existing PN pilot sequence algorithm, where D is the resolution of the fractional Doppler. 展开更多
关键词 channel estimation communication and navigation integration Orthogonal Time Frequency and Space pseudo-noise sequence red-blue frequency shift discriminator
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Near-Surface Q-Factor Estimation Using a Non-Gaussian Energy Spectrum 认领 引用
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作者 Ze-lin Li Jiang-nan Tong +2 位作者 Ya-nan Jiang Tong Chen Guo-fa Li 《Applied Geophysics》 SCIE CSCD 2026年第2期735-749,871,共15页
Accurate near-surface Q-factor estimation is essential for attenuation compensation,high-resolution imaging,and shallow-structure characterization.However,the reliability of conventional methods deteriorates in strong... Accurate near-surface Q-factor estimation is essential for attenuation compensation,high-resolution imaging,and shallow-structure characterization.However,the reliability of conventional methods deteriorates in strongly attenuating media because they commonly rely on weak-attenuation approximations or Gaussian spectrum assumptions.This paper proposes a near-surface Q-factor estimation method based on non-Gaussian energy spectrum.The proposed method has three main advantages.First,it is formulated on the energy spectrum rather than the amplitude spectrum,which improves spectral concentration and numerical stability.Second,it replaces the Gaussian assumption with an exponential frequency-weighted energy-spectrum model,thereby allowing for non-Gaussian spectrum shapes.Third,it employs an exact absorption coeffi cient derived from the complex wavenumber-Q relation,thus avoiding the weak-attenuation approximation in low-Q media.Synthetic cross-hole experiments show that the proposed method provides more accurate and more stable estimates than the spectral ratio and centroid frequency shift methods,especially under strong attenuation and noisy conditions.Field downhole data further demonstrate that the method can identify attenuation responses and support layered Q characterization in the near surface. 展开更多
关键词 near-surface attenuation Q-factor estimation energy spectrum centroid frequency shift
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Time Delay Estimation of Target Echo Signal Based on Multi-bright Spot Echoes 认领 引用
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作者 Ge Yu Fan Du +1 位作者 Xiukun Li Yan Li 《哈尔滨工程大学学报（英文版）》 CSCD 2026年第1期312-325,共14页
Accurate time delay estimation of target echo signals is a critical component of underwater target localization.In active sonar systems,echo signal processing is vulnerable to the effects of reverberation and noise in... Accurate time delay estimation of target echo signals is a critical component of underwater target localization.In active sonar systems,echo signal processing is vulnerable to the effects of reverberation and noise in the maritime environment.This paper proposes a novel method for estimating target time delay using multi-bright spot echoes,assuming the target’s size and depth are known.Aiming to effectively enhance the extraction of geometric features from the target echoes and mitigate the impact of reverberation and noise,the proposed approach employs the fractional order Fourier transform-frequency sliced wavelet transform to extract multi-bright spot echoes.Using the highlighting model theory and the target size information,an observation matrix is constructed to represent multi-angle incident signals and obtain the theoretical scattered echo signals from different angles.Aiming to accurately estimate the target’s time delay,waveform similarity coefficients and mean square error values between the theoretical return signals and received signals are computed across various incident angles and time delays.Simulation results show that,compared to the conventional matched filter,the proposed algorithm reduces the relative error by 65.9%-91.5%at a signal-to noise ratio of-25 dB,and by 66.7%-88.9%at a signal-to-reverberation ratio of−10 dB.This algorithm provides a new approach for the precise localization of submerged targets in shallow water environments. 展开更多
关键词 Multi-bright spot echoes Time-delay estimation Target echo signal Frequency sliced wavelet transform Fractional order fourier transform
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A Signal Separation Method Based on Instantaneous Frequency Embedded Continuous Wavelet Transform and Short-Time Fourier Transform 认领 引用
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作者 Qingtang Jiang 《Analysis in Theory and Applications》 CSCD 2026年第1期15-31,共17页
Modeling a non-stationary,multicomponent signal as a superposition of frequency components,each with a well-defined instantaneous frequency(IF),is crucial for extracting information,such as the underlying dynamics hid... Modeling a non-stationary,multicomponent signal as a superposition of frequency components,each with a well-defined instantaneous frequency(IF),is crucial for extracting information,such as the underlying dynamics hidden within the signal.The synchrosqueezing transform(SST)has emerged as an alternative to empirical mode decomposition(EMD)for separating non-stationary signals.However,because the SST estimates the IFs of all frequency components based on a single phase transformation,its accuracy can be limited.To address this,SST variants based on the IFembedded short-time Fourier transform(IFE-STFT)and the IF-embedded continuous wavelet transform(IFE-CWT)were developed.More recently,a direct time-frequency method called the signal separation operation(SSO)was introduced for multicomponent signal separation.SSO bypasses the second step of the two-step SST method for component recovery and is based on variants of the STFT or CWT.In this paper,we propose a direct signal separation method by combining the SSO method with IFE-CWT and IFE-STFT,creating the IFE-CWT-based SSO(IWSSO)and the IFE-STFT-based SSO(IFSSO).Both IWSSO and IFSSO directly separate multicomponent signals without the squeezing operation inherent in SST.Our algorithms and techniques yield more accurate instantaneous frequency estimates and signal separation than conventional SSO or SST methods. 展开更多
关键词 Instantaneous frequency(IF)estimation mode retrieval signal separation operator based on IF-embedded continuous wavelet transform
Environmental sensing-assisted off-grid channel estimation in UAV-enabled OTFS-ISAC systems 认领 引用
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作者 Chaojin QING Zhiying LIU +2 位作者 Wenquan HU Liang ZHAO Mian YE 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第7期515-532,共18页
Unmanned Aerial Vehicle(UAV)-enabled Orthogonal Time Frequency Space(OTFS)-Integrated Sensing And Communication(ISAC)is a promising technique that simultaneously provides the enhanced Sensing and Communication(S&C... Unmanned Aerial Vehicle(UAV)-enabled Orthogonal Time Frequency Space(OTFS)-Integrated Sensing And Communication(ISAC)is a promising technique that simultaneously provides the enhanced Sensing and Communication(S&C)services,while holding significant potential to mitigate the high-Doppler effect.To achieve the advantages of UAV-enabled OTFS-ISAC systems,accurate channel estimation is crucial.However,this process faces a significant challenge of the off-grid phenomenon in the Delay-Doppler(DD)domain,promoting the development of offgrid channel estimation methods.Regrettably,most existing off-grid channel estimation methods mainly focus on optimizing signal modeling,resulting in significantly high computational complexity and leaving substantial room for accuracy improvement.To address these issues,inspired by the benefits of environmental sensing,a sensing-assisted off-grid channel estimation method is proposed in this paper.Specifically,passive UAV radar is employed to sense the location and velocity of ground User Equipment(gUE).Based on Ground-to-Air(G2A)communication link,a radio map is constructed,which captures comprehensive environmental features and signal blockage information.We extract the delay and Doppler priors from this environmental information,which provide crucial insights in DD domain channel from a perspective of propagation environment.Subsequently,by leveraging this prior information,a Sensing-Assisted Grid Calibration-based OGSBI(SAGCSBI)method and a Path Refinement-based Enhanced Channel Estimation(PREnCE)method are developed.The proposed methods reduce off-grid errors and mitigate path superposition by integrating environmental information and signal modeling.Simulation results verify the superior performance of the proposed channel estimation methods over state-of-the-art methods and demonstrate the robustness against parameter variations. 展开更多
关键词 Channel estimation Delay-Doppler domain Environmental sensing Off-grid Orthogonal time frequency space
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Estimation of DOA and Doppler Frequency on Nonideal UCA 认领 引用 被引量：2
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作者 陶建武 石要武 常文秀 《Chinese Journal of Aeronautics》 EI CAS 2004年第2期106-111,共6页
The problem of estimating direction of arrivals (DOA) and Doppler frequency for many sources is considered in the presence of general array errors (such as amplitude and phase error of sensors, setting position error ... The problem of estimating direction of arrivals (DOA) and Doppler frequency for many sources is considered in the presence of general array errors (such as amplitude and phase error of sensors, setting position error of sensors). Adopting direct array manifold in a uniform circular array (UCA), the estimation of Doppler frequency can be obtained by DOA matrix. Based on analyzing the statistic characters of general array errors, the estimation of DOA can be obtained by Weight Total Least Squares. Numerical results illustrate that the estimator is robust to general array errors and show the capabilities of the estimator. 展开更多
关键词 estimation of DOA estimation of Doppler frequency UCA general array error
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Architecture design of GPS software receiver and implementation of its acquisition algorithm with fine frequency estimation 认领 引用 被引量：8
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作者 祝雪芬 陈熙源 李滋刚 《Journal of Southeast University(English Edition)》 EI CAS 2008年第1期38-41,共4页
The design of a global positioning system （GPS） software receiver is introduced. This design uses the concept of software radio, and it consists of the following parts： front-end, acquisition, tracking, synchroniza... The design of a global positioning system （GPS） software receiver is introduced. This design uses the concept of software radio, and it consists of the following parts： front-end, acquisition, tracking, synchronization, navigation solution and some assisting modules. In the acquisition module, the acquisition algorithm based on circular correlation is utilized. The input data and the local code are converted into the frequency domain by means of the fast Fourier transform （FFT）. After performing circular correlation, the initial phase of the C/A code can be obtained and the cartier frequency can be found in 1 kHz frequency resolution, which is too coarse to use for the tracking loop. In order to improve the frequency resolution, the fine frequency estimation through a phase relationship is then achieved, by which, the frequency resolution is improved dramatically. Experiments show that the inaccuracy of the carrier frequency can be estimated within a few hertz by the fine frequency estimation method, and the fine frequency attained can be directly used for the tracking loop. 展开更多
关键词 GPS software receiver acquisition algorithm circular correlation fine frequency estimation
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Efficient integer frequency offset estimation for OFDM systems 认领 引用 被引量：2
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作者 吴贇 Ding Ming +2 位作者 Luo Hanwen Huang Jianguo Liu Renmao 《High Technology Letters》 EI CAS 2007年第2期164-168,共5页
An efficient scheme of integer frequency offset estimate for orthogonal frequency division multiplexing （OFDM） systems is proposed based on a training symbol with several identicalparts. In this scheme, the received... An efficient scheme of integer frequency offset estimate for orthogonal frequency division multiplexing （OFDM） systems is proposed based on a training symbol with several identicalparts. In this scheme, the received training symbol is first reshaped into several sub-symbols.It shows that the reshaping process in-troduees time diversity multiplexing.After a special fast Fourier transform （FFT） algorithm is applied to the sub-symbol,the integer frequency is estimated by finding the maximum magnitude of the resulting fre-quency domain signal.To improve the estimate performance,diversity combining methods are presented to makefull use of the multiple frequency domain sub-symbols.Compared to the traditional scheme, theproposed one has an improved estimate performance demonstrated by the computation simulation, while maintaining a very low complexity. 展开更多
关键词 OFDM estimation integer carrier frequency offset FFT
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Continuous time-varying Q-factor estimation method in the time-frequency domain 认领 引用 被引量：2
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作者 Wang Qing-Han Liu Yang +1 位作者 Liu Cai Zheng Zhi-Sheng 《Applied Geophysics》 SCIE CSCD 2020年第5期844-856,904,共13页
The Q-factor is an important physical parameter for characterizing the absorption and attenuation of seismic waves propagating in underground media,which is of great signifi cance for improving the resolution of seism... The Q-factor is an important physical parameter for characterizing the absorption and attenuation of seismic waves propagating in underground media,which is of great signifi cance for improving the resolution of seismic data,oil and gas detection,and reservoir description.In this paper,the local centroid frequency is defi ned using shaping regularization and used to estimate the Q values of the formation.We propose a continuous time-varying Q-estimation method in the time-frequency domain according to the local centroid frequency,namely,the local centroid frequency shift(LCFS)method.This method can reasonably reduce the calculation error caused by the low accuracy of the time picking of the target formation in the traditional methods.The theoretical and real seismic data processing results show that the time-varying Q values can be accurately estimated using the LCFS method.Compared with the traditional Q-estimation methods,this method does not need to extract the top and bottom interfaces of the target formation;it can also obtain relatively reasonable Q values when there is no eff ective frequency spectrum information.Simultaneously,a reasonable inverse Q fi ltering result can be obtained using the continuous time-varying Q values. 展开更多
关键词 local centroid frequency local time-frequency transform Q-factor estimation shaping regularization
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Blind carrier frequency estimation for phase shift keying signals in low signal to noise ratio 认领 引用 被引量：1
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作者 Wang Xiaofeng Zhang Guoyi +1 位作者 Tian Runlan Li Dawei 《强激光与粒子束》 EI CAS CSCD 北大核心 2015年第10期240-244,共5页
In order to solve the problem of carrier frequency blind estimation of PSK signals in electronic reconnaissance, a new estimation method was proposed. The phase shift keying（PSK） signal was divided into several over... In order to solve the problem of carrier frequency blind estimation of PSK signals in electronic reconnaissance, a new estimation method was proposed. The phase shift keying（PSK） signal was divided into several overlapping intervals which had equal length, and the spectrum concentration measures of every interval were extracted by the FFT. And then, using the grid-density clustering, the spectrum concentration measures were classified into two categories, the narrowband spectrum interval and the wideband spectrum interval. The narrowband spectrum interval was regarded as the characteristic class. The spectrums of the characteristic class were accumulated to estimate the carrier frequency of PSK signal. The proposed method had avoided the non linear operation in the traditional PSK signal carrier frequency estimation algorithm. Thus, the signal to noise ratio （SNR） threshold was remarkably decreased. Moreover, the proposed method did not need the prior knowledge of the signal, which was suitable to the electronic reconnaissance occasion. Experimental results had verified the validity of the proposed estimation method in low SNR. 展开更多
关键词 electronic reconnaissance PSK signal carrier frequency estimation low SNR
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Adaptive compensating method for Doppler frequency shift using LMS and phase estimation 认领 引用 被引量：7
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作者 Jing Qingfeng Guo Qing 《Journal of Systems Engineering and Electronics》 SCIE EI 2009年第5期913-919,共7页
The novel compensating method directly demodulates the signals without the carrier recovery processes, in which the carrier with original modulation frequency is used as the local coherent carrier. In this way, the ph... The novel compensating method directly demodulates the signals without the carrier recovery processes, in which the carrier with original modulation frequency is used as the local coherent carrier. In this way, the phase offsets due to frequency shift are linear. Based on this premise, the compensation processes are： firstly, the phase offsets between the baseband neighbor-symbols after clock recovery is unbiasedly estimated among the reference symbols; then, the receiving signals symbols are adjusted by the phase estimation value; finally, the phase offsets after adjusting are compensated by the least mean squares （LMS） algorithm. In order to express the compensation processes and ability clearly, the quadrature phase shift keying （QPSK） modulation signals are regarded as examples for Matlab simulation. BER simulations are carried out using the Monte-Carlo method. The learning curves are obtained to study the algorithm＇s convergence ability. The constellation figures are also simulated to observe the compensation results directly. 展开更多
关键词 Doppler frequency shift least mean square minimum phase shift keying unbiased estimation Matlab simulation.
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Modified OMP method for multi-target parameter estimation in frequency-agile distributed MIMO radar 认领 引用 被引量：3
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作者 XING Wenge ZHOU Chuanrui WANG Chunlei 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2022年第5期1089-1094,共6页
Introducing frequency agility into a distributed multipleinput multiple-output(MIMO)radar can significantly enhance its anti-jamming ability.However,it would cause the sidelobe pedestal problem in multi-target paramet... Introducing frequency agility into a distributed multipleinput multiple-output(MIMO)radar can significantly enhance its anti-jamming ability.However,it would cause the sidelobe pedestal problem in multi-target parameter estimation.Sparse recovery is an effective way to address this problem,but it cannot be directly utilized for multi-target parameter estimation in frequency-agile distributed MIMO radars due to spatial diversity.In this paper,we propose an algorithm for multi-target parameter estimation according to the signal model of frequency-agile distributed MIMO radars,by modifying the orthogonal matching pursuit(OMP)algorithm.The effectiveness of the proposed method is then verified by simulation results. 展开更多
关键词 distributed multiple-input multiple-output(MIMO)radar multi-target parameter estimation frequency agility modified orthogonal matching pursuit(OMP)method
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Blind parameter estimation of pseudo-random binary code-linear frequency modulation signal based on Duffing oscillator at low SNR 认领 引用 被引量：1
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作者 Ke Wang Xiaopeng Yan† +2 位作者 Ze Li Xinhong Hao Honghai Yu 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第5期312-319,共8页
Conventional parameter estimation methods for pseudo-random binary code-linear frequency modulation(PRBC-LFM)signals require prior knowledge,are computationally complex,and exhibit poor performance at low signal-to-no... Conventional parameter estimation methods for pseudo-random binary code-linear frequency modulation(PRBC-LFM)signals require prior knowledge,are computationally complex,and exhibit poor performance at low signal-to-noise ratios(SNRs).To overcome these problems,a blind parameter estimation method based on a Duffing oscillator array is proposed.A new relationship formula among the state of the Duffing oscillator,the pseudo-random sequence of the PRBC-LFM signal,and the frequency difference between the PRBC-LFM signal and the periodic driving force signal of the Duffing oscillator is derived,providing the theoretical basis for blind parameter estimation.Methods based on amplitude method,short-time Fourier transform method,and power spectrum entropy method are used to binarize the output of the Duffing oscillator array,and their performance is compared.The pseudo-random sequence is estimated using Duffing oscillator array synchronization,and the carrier frequency parameters are obtained by the relational expressions and characteristics of the difference frequency.Simulation results show that this blind estimation method overcomes limitations in prior knowledge and maintains good parameter estimation performance up to an SNR of-35 dB. 展开更多
关键词 Duffing oscillator pseudo-random binary code-linear frequency modulation(PRBC-LFM)signal blind parameter estimation low signal-to-noise ratio(SNR)
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Time-Frequency Bandwidth Product Estimation of Sinusoidal Non-Linear Chirp Keying Scheme 认领 引用 被引量：1
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作者 Zhiguo Sun Xiaoyan Ning Danyang Tian 《China Communications》 SCIE CSCD 2017年第8期184-194,共11页
Sine Non-linear Chirp Keying(SNCK) is a kind of high-efficient modulation scheme, which provides a potential new beamforming method in communication and radar systems. It has been proved to have advantages in some par... Sine Non-linear Chirp Keying(SNCK) is a kind of high-efficient modulation scheme, which provides a potential new beamforming method in communication and radar systems. It has been proved to have advantages in some parameter estimation issues over conventional modulation schemes. In this paper, a novel transform termed as Discrete Sinusoidal Frequency Modulation transform(DSFMT) is proposed. Then, the DSFMT of SNCK signal is deduced and classified into three types, based on which, the time-bandwidth product is estimated by the proposed algorithm. Simulation results show that the noise has a signifi cant impact on the localization of the peak value and the time-bandwidth product can be estimated by using local ratio values when. 展开更多
关键词 parameter estimation time-bandwidth product sine non-linear chirp keying（SNCK） discrete sinusoidal frequency modulation transform（DSFMT）
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ESTIMATION OF CARRIER FREQUENCY OFFSETS FOR MIMO SYSTEMS WITH DISTRIBUTED TRANSMIT ANTENNAS 认领 引用 被引量：2
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作者 Deng Kai Tang Youxi Lei Xia Li Shaoqian 《Journal of Electronics(China)》 2007年第4期455-461,共7页
The problem of estimating the carrier frequency offsets in Multiple-Input Multiple-Output (MIMO) systems with distributed transmit antennas is addressed. It is supposed that the transmit antennas are distributed while... The problem of estimating the carrier frequency offsets in Multiple-Input Multiple-Output (MIMO) systems with distributed transmit antennas is addressed. It is supposed that the transmit antennas are distributed while the receive antennas are still centralized, and the general case where both the time delays and the frequency offsets are possibly different for each transmit antenna is considered. The channel is supposed to be frequency flat, and the macroscopic fading is also taken into consideration. A carrier frequency offset estimator based on Maximum Likelihood (ML) is proposed, which can separately estimate the frequency offset for each transmit antenna and exploit the spatial diversity. The Cramer-Rao Bound (CRB) for synchronous MIMO (i.e., the time delays for each transmit antenna are all equal) is also derived. Simulation results are given to illustrate the per- formance of the estimator and compare it with the CRB. It is shown that the estimator can provide satisfactory frequency offset estimates and its performance is close to the CRB for the Signal-to-Noise Ratio (SNR) below 20dB. 展开更多
关键词 Multiple-Input Multiple-Output （MIMO） Distributed antenna Carrier frequency offset estimation Maximum Likelihood （ML） Cramer-Rao Bound （CRB）
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Parameter estimation method for a linear frequency modulation signal with a Duffing oscillator based on frequency periodicity 认领 引用
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作者 张宁哲 闫晓鹏 +2 位作者 吕明慧 陈秀梅 黄鼎琨 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第8期237-246,共10页
In view of the complexity of existing linear frequency modulation(LFM)signal parameter estimation methods and the poor antinoise performance and estimation accuracy under a low signal-to-noise ratio(SNR),a parameter e... In view of the complexity of existing linear frequency modulation(LFM)signal parameter estimation methods and the poor antinoise performance and estimation accuracy under a low signal-to-noise ratio(SNR),a parameter estimation method for LFM signals with a Duffing oscillator based on frequency periodicity is proposed in this paper.This method utilizes the characteristic that the output signal of the Duffing oscillator excited by the LFM signal changes periodically with frequency,and the modulation period of the LFM signal is estimated by autocorrelation processing of the output signal of the Duffing oscillator.On this basis,the corresponding relationship between the reference frequency of the frequencyaligned Duffing oscillator and the frequency range of the LFM signal is analyzed by the periodic power spectrum method,and the frequency information of the LFM signal is determined.Simulation results show that this method can achieve high-accuracy parameter estimation for LFM signals at an SNR of-25 dB. 展开更多
关键词 linear frequency modulation(LFM)signal Duffing oscillator frequency periodicity parameter estimation
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H_∞ fault estimation for a class of linear time-delay systems in finite frequency domain 认领 引用
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作者 Quanchao Dong Maiying Zhong Steven X. Ding 《Journal of Systems Engineering and Electronics》 SCIE EI 2010年第5期835-841,共7页
This paper deals with the problem of H∞ fault estimation for linear time-delay systems in finite frequency domain.First a generalized coordinate change is applied to the original system such that in the new coordinat... This paper deals with the problem of H∞ fault estimation for linear time-delay systems in finite frequency domain.First a generalized coordinate change is applied to the original system such that in the new coordinates all the time-delay terms are injected by the system＇s input and output.Then an observer-based H∞ fault estimator with input and output injections is proposed for fault estimation with known frequency range.With the aid of Generalized Kalman-Yakubovich-Popov lemma,sufficient conditions on the existence of the H∞ fault estimator are derived and a solution to the observer gain matrices is obtained by solving a set of linear matrix inequalities.Finally,a numerical example is given to illustrate the effectiveness of the proposed method. 展开更多
关键词 fault estimation time-delay generalized coordinate change generalized Kalman-Yakubovich-Popov lemma finite frequency domain.
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Robust Frequency Estimation Under Additive Mixture Noise 认领 引用
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作者 Yuan Chen Yulu Tian +2 位作者 Dingfan Zhang Longting Huang Jingxin Xu 《Computers, Materials & Continua》 SCIE EI 2022年第7期1671-1684,共14页
In many applications such as multiuser radar communications and astrophysical imaging processing,the encountered noise is usually described by the finite sum ofα-stable(1≤α<2)variables.In this paper,a new parame... In many applications such as multiuser radar communications and astrophysical imaging processing,the encountered noise is usually described by the finite sum ofα-stable(1≤α<2)variables.In this paper,a new parameter estimator is developed,in the presence of this new heavy-tailed noise.Since the closed-formPDF of theα-stable variable does not exist exceptα=1 andα=2,we take the sum of the Cauchy(α=1)and Gaussian(α=2)noise as an example,namely,additive Cauchy-Gaussian(ACG)noise.The probability density function(PDF)of the mixed random variable,can be calculated by the convolution of the Cauchy’s PDF and Gaussian’s PDF.Because of the complicated integral in the PDF expression of the ACG noise,traditional estimators,e.g.,maximum likelihood,are analytically not tractable.To obtain the optimal estimates,a new robust frequency estimator is devised by employing the Metropolis-Hastings(M-H)algorithm.Meanwhile,to guarantee the fast convergence of the M-H chain,a new proposal covariance criterion is also devised,where the batch of previous samples are utilized to iteratively update the proposal covariance in each sampling process.Computer simulations are carried out to indicate the superiority of the developed scheme,when compared with several conventional estimators and the Cramér-Rao lower bound. 展开更多
关键词 Frequency estimation additive cauchy-gaussian noise voigt profile metropolis-hastings algorithm cramér-rao lower bound
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Parameter estimation of maneuvering targets in OTHR based on sparse time-frequency representation 认领 引用 被引量：4
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作者 Jinfeng Hu Xuan He +3 位作者 Wange Li Hui Ai Huiyong Li Julan Xie 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2016年第3期574-580,共7页
This paper proposes a new method for estimating the parameter of maneuvering targets based on sparse time-frequency transform in over-the-horizon radar（OTHR）. In this method, the sparse time-frequency distribution o... This paper proposes a new method for estimating the parameter of maneuvering targets based on sparse time-frequency transform in over-the-horizon radar（OTHR）. In this method, the sparse time-frequency distribution of the radar echo is obtained by solving a sparse optimization problem based on the short-time Fourier transform. Then Hough transform is employed to estimate the parameter of the targets. The proposed algorithm has the following advantages： Compared with the Wigner-Hough transform method, the computational complexity of the sparse optimization is low due to the application of fast Fourier transform（FFT）. And the computational cost of Hough transform is also greatly reduced because of the sparsity of the time-frequency distribution. Compared with the high order ambiguity function（HAF） method, the proposed method improves in terms of precision and robustness to noise. Simulation results show that compared with the HAF method, the required SNR and relative mean square error are 8 dB lower and 50 dB lower respectively in the proposed method. While processing the field experiment data, the execution time of Hough transform in the proposed method is only 4% of the Wigner-Hough transform method. 展开更多
关键词 over-the-horizon radar（OTHR） maneuvering tar-get parameter estimation sparse time-frequency transform Hough transform
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Relative Peak Frequency Increment Method for Quantitative Thin-Layer Thickness Estimation 认领 引用
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作者 孙鲁平 郑晓东 首皓 《Journal of Earth Science》 SCIE EI CAS CSCD 2013年第6期1068-1078,共11页
Quantitative thickness estimation of thin-layer is a great challenge in seismic exploration, especially for thin-layer below tuning thickness. In this article, we analyzed the seismic response cha- racteristics of rhy... Quantitative thickness estimation of thin-layer is a great challenge in seismic exploration, especially for thin-layer below tuning thickness. In this article, we analyzed the seismic response cha- racteristics of rhythm and gradual type of thin-layer wedge models and presented a new method for thin-layer thickness estimation which uses relative peak frequency increment. This method can de- scribe the peak frequency to thickness relationship of rhythm and gradual thin-layers in unified equa- tion while the traditional methods using amplitude information cannot. What＇s more, it won＇t be in- fluenced by the absolute value of thin-layer reflection coefficient and peak frequency of wavelet. The unified equations were presented which can be used for rhythm and gradual thin-layer thickness cal- culation. Model tests showed that the method we introduced has a high precision and it doesn＇t need to determine the value of top or bottom reflection coefficient, so it has a more wide application in practice. The application of real data demonstrated that the relative peak frequency increment attribute can character the plane distribution feature and thickness characteristic of channel sand bodies very well. 展开更多
关键词 thin-layer quantitative estimation relative peak frequency increment Ricker wavelet.
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