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Effective DOA Estimation Under Low Signal-to-Noise Ratio Based on Multi-Source Information Meta Fusion 被引量:2
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作者 Yun Wu Xiukun Li Zhimin Cao 《Journal of Beijing Institute of Technology》 EI CAS 2021年第4期377-396,共20页
Efficiently performing high-resolution direction of arrival(DOA)estimation under low signal-to-noise ratio(SNR)conditions has always been a challenge task in the literatures.Obvi-ously,in order to address this problem... Efficiently performing high-resolution direction of arrival(DOA)estimation under low signal-to-noise ratio(SNR)conditions has always been a challenge task in the literatures.Obvi-ously,in order to address this problem,the key is how to mine or reveal as much DOA related in-formation as possible from the degraded array outputs.However,it is certain that there is no per-fect solution for low SNR DOA estimation designed in the way of winner-takes-all.Therefore,this paper proposes to explore in depth the complementary DOA related information that exists in spa-tial spectrums acquired by different basic DOA estimators.Specifically,these basic spatial spec-trums are employed as the input of multi-source information fusion model.And the multi-source in-formation fusion model is composed of three heterogeneous meta learning machines,namely neural networks(NN),support vector machine(SVM),and random forests(RF).The final meta-spec-trum can be obtained by performing a final decision-making method.Experimental results illus-trate that the proposed information fusion based DOA estimation method can really make full use of the complementary information in the spatial spectrums obtained by different basic DOA estim-ators.Even under low SNR conditions,promising DOA estimation performance can be achieved. 展开更多
关键词 direction of arrival(DOA) signal-to-noise ratio(snr) information fusion meta-learn-ing spatial spectrum
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Influence of signal-to-noise ratio on accuracy of spectral analysis by near infrared spectroscopy 被引量:1
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作者 ZHUANG Xin-gang SHI Xue-shun +3 位作者 LIU Hong-bo LIU Chang-ming ZHANG Peng-ju WANG Heng-fei 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2020年第3期211-216,共6页
As one of the important indicators of spectrometer,signal-to-noise ratio(SNR)reflects the ability of spectrometer to detect weak signals.To investigate the influence of SNR on the prediction accuracy of spectral analy... As one of the important indicators of spectrometer,signal-to-noise ratio(SNR)reflects the ability of spectrometer to detect weak signals.To investigate the influence of SNR on the prediction accuracy of spectral analysis,we first introduce the major factors affecting the spectral SNR.Taking green tea as an example,the influence of spectral SNR on the prediction accuracy of the origin identification model is analyzed by experiments.At the same time,the relationship between the spectral SNR and prediction accuracy of spectral analysis model is fitted.Based on this,the common methods for improving the spectral SNR are discussed.The results show that the accuracy of the prediction set model first decreases slowly,then decreases linearly,and finally tends to be flat as the spectral SNR decreases.Through calculation,in order to achieve the prediction accuracy of prediction model reaching 90%and 85%,the spectral SNR is required to be higher than 23.42 dB and 21.16 dB,respectively.The overall results provide certain parameters support for the development of new online analytical spectroscopic instruments,especially for the technical indicators of SNR. 展开更多
关键词 near infrared spectroscopy signal-to-noise ratio(snr) partial least squares(PLS) spectral analysis green tea
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Signal-to-noise ratio comparison of angular signal radiography and phase stepping method
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作者 Wali Faiz 朱佩平 +4 位作者 胡仁芳 高昆 吴朝 鲍园 田扬超 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第12期173-178,共6页
Grating-based x-ray phase contrast imaging has the potential to be applied in future medical applications as it is compatible with both laboratory and synchrotron source. However, information retrieval methods are imp... Grating-based x-ray phase contrast imaging has the potential to be applied in future medical applications as it is compatible with both laboratory and synchrotron source. However, information retrieval methods are important because acquisition speed, scanning mode, image quality, and radiation dose depend on them. Phase-stepping (PS) is a widely used method to retrieve information, while angular signal radiography (ASR) is a newly established method. In this manuscript, signal-to-noise ratios (SNRs) of ASR are compared with that of PS. Numerical experiments are performed to validate theoretical results. SNRs comparison shows that for refraction and scattering images ASR has higher SNR than PS method, while for absorption image both methods have same SNR. Therefore, our conclusions would have guideline in future preclinical and clinical applications. 展开更多
关键词 angular signal radiography (ASR) phase-stepping (PS) signal-to-noise ratio (snrs) information retrieval method
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Speech Separation Methodology for Hearing Aid
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作者 Joseph Sathiadhas Esra Y.Sukhi 《Computer Systems Science & Engineering》 SCIE EI 2023年第2期1659-1678,共20页
In the design of hearing aids(HA),the real-time speech-enhancement is done.The digital hearing aids should provide high signal-to-noise ratio,gain improvement and should eliminate feedback.In generic hearing aids the ... In the design of hearing aids(HA),the real-time speech-enhancement is done.The digital hearing aids should provide high signal-to-noise ratio,gain improvement and should eliminate feedback.In generic hearing aids the perfor-mance towards different frequencies varies and non uniform.Existing noise can-cellation and speech separation methods drops the voice magnitude under the noise environment.The performance of the HA for frequency response is non uni-form.Existing noise suppression methods reduce the required signal strength also.So,the performance of uniform sub band analysis is poor when hearing aid is con-cern.In this paper,a speech separation method using Non-negative Matrix Fac-torization(NMF)algorithm is proposed for wavelet decomposition.The Proposed non-uniformfilter-bank was validated by parameters like band power,Signal-to-noise ratio(SNR),Mean Square Error(MSE),Signal to Noise and Dis-tortion Ratio(SINAD),Spurious-free dynamic range(SFDR),error and time.The speech recordings before and after separation was evaluated for quality using objective speech quality measures International Telecommunication Union-Telecommunication standard ITU-T P.862. 展开更多
关键词 Speech separation waveletfilter independent component analysis(ICA) non-negative matrix factorization(NMF) fejer-korovkin(FK) signal-to-noise ratio(snr)
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Improved Goldstein filter for InSAR noise reduction based on local SNR 被引量:7
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作者 SUN Qian LI Zhi-wei +3 位作者 ZHU Jian-jun DING Xiao-li HU Jun XU Bing 《Journal of Central South University》 SCIE EI CAS 2013年第7期1896-1903,共8页
Although the modified Goldstein filter based on the local signal-to-noise (SNR) has been proved to be superior to the classical Goldstein and Baran filters with more comprehensive filter parameter, its adaptation is... Although the modified Goldstein filter based on the local signal-to-noise (SNR) has been proved to be superior to the classical Goldstein and Baran filters with more comprehensive filter parameter, its adaptation is not always sufficient in the reduction of phase noise. In this work, the local SNR-based Goldstein filter is further developed with the improvements in the definition of the local SNR and the adaption of the filtering patch size. What's more, for preventing the loss of the phase signal caused by the excessive filtering, an iteration filtering operation is also introduced in this new algorithm. To evaluate the performance of the proposed algorithm, both a simulated digital elevation model (DEM) interferogram and real SAR deformation interferogram spanning the L' Aquila earthquake are carried out. The quantitative results from the simulated and real data reveal that up to 79.5% noises can be reduced by the new filter, indicating 9%-32% improvements over the previous local SNR-based Goldstein filter. This demonstrates that the new filter is not only equipped with sufficient adaption, but also can suppress the phase noise without the sacrifice of the phase signal. 展开更多
关键词 interferometric synthetic aperture radar (InSAR) Goldstein filter signal-to-noise (snr adaptivity
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Influence of array elements’ consistency on SNR of hydrophone array 被引量:3
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作者 ZHANG Xiao-yong SHANG Zhen-zhen +1 位作者 JI Song-xiang ZHANG Guo-jun 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2019年第3期241-245,共5页
The influence of array element’s consistency on the hydrophone array’s signal-to-noise ratio (SNR) is studied. The consistency of array elements means the outputs of all the array’s elements are the same, that is t... The influence of array element’s consistency on the hydrophone array’s signal-to-noise ratio (SNR) is studied. The consistency of array elements means the outputs of all the array’s elements are the same, that is to say, the outputs have the same phase and amplitude when their inputs are the same. The relationship between the SNR and the correlation coefficient of signal and the relationship between the SNR and the correlation coefficient of noise are given. Hydrophone array’s gain with the output of elements’ inconsistent phase and amplitude is analyzed theoretically. When the signal is single-frequency, the gain expression of two-elements array is deduced. Then the gain is calculated when the phase difference is 10° and the amplitude difference is 3 dB. The theoretical analysis is verified through simulation. The simulation results show the variation rule of array’s SNR when the consistency changes: the array SNR gain is greatly affected by the consistency of the elements’ output and the gain decreases as the consistency decreases and the gain may be negative when the amplitude response becomes worse. 展开更多
关键词 HYDROPHONE element array CONSISTENCY signal-to-noise ratio (snr) GAIN
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A BLIND SNR ESTIMATOR FOR DIGITAL BANDPASS SIGNALS 被引量:4
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作者 Sui Dan Ge Lindong 《Journal of Electronics(China)》 2008年第1期7-13,共7页
A subspace-based blind Signal-to-Noise Ratio (SNR) estimation algorithm for digital bandpass signals in Additive White Gaussian Noise (AWGN) channel is discussed. The lower bounds of the mean and variance of the estim... A subspace-based blind Signal-to-Noise Ratio (SNR) estimation algorithm for digital bandpass signals in Additive White Gaussian Noise (AWGN) channel is discussed. The lower bounds of the mean and variance of the estimation are derived, and simulations are performed for the commonly used digital bandpass signals, such as MPSK (M=2, 4, 8), MFSK (M=2, 4) and MQAM (M=16, 64, 128, 256) signals. Theoretical analyses and simulation results indicate that the proposed algorithm is ef- fective even when the SNR is below 0dB. Furthermore, the algorithm can provide a blind estimator in that it needs neither the parameters of the received signals, such as the carrier frequency, symbol rate and modulation scheme, nor the synchronization of the system. 展开更多
关键词 signal-to-noise Ratio (snr estimation Blind algorithm Performance analysis Bandpass signals Subspace projection
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Long term integration of radar signals with unknown Doppler shift for ubiquitous radar 被引量:4
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作者 Qinglong Bao Zengping Chen Yue Zhang Jian Yang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2011年第2期219-227,共9页
Ubiquitous radar is a new radar system that provides continuous and uninterrupted multifunction capability within a coverage volume. Continuous coverage from close-in "pop-up" targets in clutter to long-range target... Ubiquitous radar is a new radar system that provides continuous and uninterrupted multifunction capability within a coverage volume. Continuous coverage from close-in "pop-up" targets in clutter to long-range targets impacts selection of waveform parameters. The coherent processing interval (CPI) must be long enough to achieve a certain signal-to-noise ratio (SNR) that ensures the efficiency of detection. The condition of detection in the case of low SNR is analyzed, and three different cases that would occur during integration are discussed and a method to determine the CPI is presented. The simulation results show that targets detection with SNR as low as -26 dB in the experimental system can possibly determine the CPI. 展开更多
关键词 ubiquitous radar low signal-to-noise ratio (snr coherent processing interval (CPI) coherent integration non-coherent integration.
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Nonsaturation Throughput Enhancement of IEEE 802.11b Distributed Coordination Function for Heterogeneous Traffic under Noisy Environment 被引量:5
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作者 Dhanasekaran Senthilkumar A. Krishnan 《International Journal of Automation and computing》 EI 2010年第1期95-104,共10页
In this paper, we propose a mechanism named modified backoff (MB) mechanism to decrease the channel idle time in IEEE 802.11 distributed coordination function (DCF). In the noisy channel, when signal-to-noise rat... In this paper, we propose a mechanism named modified backoff (MB) mechanism to decrease the channel idle time in IEEE 802.11 distributed coordination function (DCF). In the noisy channel, when signal-to-noise ratio (SNR) is low, applying this mechanism in DCF greatly improves the throughput and lowers the channel idle time. This paper presents an analytical model for the performance study of IEEE 802.11 MB-DCF for nonsaturated heterogeneous traffic in the presence of transmission errors. First, we introduce the MB-DCF and compare its performance to IEEE 802.11 DCF with binary exponential backoff (BEB). The IEEE 802.11 DCF with BEB mechanism suffers from more channel idle time under low SNR. The MB-DCF ensures high throughput and low packet delay by reducing the channel idle time under the low traffic in the network. However, to the best of the authors' knowledge, there are no previous works that enhance the performance of the DCF under imperfect wireless channel. We show through analysis that the proposed mechanism greatly outperforms the original IEEE 802.11 DCF in the imperfect channel condition. The effectiveness of physical and link layer parameters on throughput performance is explored. We also present a throughput investigation of the heterogeneous traffic for different radio conditions. 展开更多
关键词 IEEE 802.11 medium access control (MAC) distributed coordination function (DCF) nonsaturated traffic heteroge- neous traffic signal-to-noise ratio (snr binary exponential backoff (BEB).
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A NOVEL METHOD FOR ESTIMATING THE SNR OF UNKNOWN EMITTER SIGNAL 被引量:4
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作者 Han Jun He Minghao +1 位作者 Tang Zhikai Hao Yuan 《Journal of Electronics(China)》 2010年第1期134-138,共5页
It is important to estimate the Signal-to-Noise Ratio(SNR) of unknown emitter signal accurately.In order to resolve the disadvantages of present algorithm,a novel method is proposed in this letter.We extract and norma... It is important to estimate the Signal-to-Noise Ratio(SNR) of unknown emitter signal accurately.In order to resolve the disadvantages of present algorithm,a novel method is proposed in this letter.We extract and normalize the information of zero frequency of received signal by the Wigner-Vile Distribution(WVD) transformation and then get the approximate power of original signal by mathematic transformation,at last,we get the estimate value of SNR by the known account formula of SNR.Simulation results show that it is correct and feasible. 展开更多
关键词 signal-to-noise Ratio(snr) estimation Wigner-Vile Distribution(WVD) transformation Signal power
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Blind parameter estimation of pseudo-random binary code-linear frequency modulation signal based on Duffing oscillator at low SNR 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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SUBSPACE-BASED NOISE VARIANCE AND SNR ESTIMATION FOR MIMO OFDM SYSTEMS 被引量:1
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作者 Xu Xiaodong Jing Ya +1 位作者 Zhao Junhui You Xiaohu 《Journal of Electronics(China)》 2006年第2期176-180,共5页
This paper proposes a subspace-based noise variance and Signal-to-Noise Ratio (SNR) estimation algorithm for Multi-Input Multi-Output (MIMO) wireless Orthogonal Frequency Division Multiplexing (OFDM) systems. The spec... This paper proposes a subspace-based noise variance and Signal-to-Noise Ratio (SNR) estimation algorithm for Multi-Input Multi-Output (MIMO) wireless Orthogonal Frequency Division Multiplexing (OFDM) systems. The special training sequences with the property of orthogonality and phase shift orthogonality are used in pilot tones to obtain the estimated channel correlation matrix. Partitioning the observation space into a delay subspace and a noise subspace, we achieve the measurement of noise variance and SNR. Simulation results show that the proposed estimator can obtain accurate and real-time measurements of the noise variance and SNR for various multipath fading channels, demonstrating its strong robustness against different channels. 展开更多
关键词 Multi-Input Multi-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) Noise variance signal-to-noise Ratio (snr Delay subspace Channel correlation matrix
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Effect of Peak Power and Pulse Width on Coherent Doppler Wind Lidar’s SNR 被引量:4
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作者 REN Yong WU Xuefei +1 位作者 TAO Fa CAO Haishuai 《Instrumentation》 2022年第2期26-32,共7页
The laser device is the core component of coherent Doppler wind lidar.The peak power and pulse width of laser transmitting pulse have important effects on SNR.Based on coherent Doppler wind pulse lidar,the peak power ... The laser device is the core component of coherent Doppler wind lidar.The peak power and pulse width of laser transmitting pulse have important effects on SNR.Based on coherent Doppler wind pulse lidar,the peak power and pulse width influence on SNR is studied on the theoretical derivation and analysis,and the results show that the higher the peak power can realize the greater the signal-to-noise ratio of coherent Doppler wind lidar.But when the peak power is too large,the laser pulse may appear nonlinear phenomenon,which cause the damage of the laser.So,the peak power must be less than the stimulated brillouin scattering power threshold.Increasing the pulse width can make the laser device to output more energy,but it will also make the spatial resolution lower,and the influence of turbulence on SNR will be greater.After a series of simulation analyses,it can be concluded that when the peak power is 650W and the pulse width is 340ns,the SNR of the system can be maximized.In addition,the coherent Doppler wind lidar system is set up to carry out corresponding experimental verification.The experimental results are consistent with the theoretical analysis and simulation,which verifies the correctness of the theoretical analysis and simulation results.It provides theoretical basis and practical ex-perience for the design of laser transmitting pulse in coherent Doppler wind lidar system. 展开更多
关键词 Coherent Lidar Fiber Laser Peak Power Pulse Width signal-to-noise Ratio(snr)
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Parametric SNR Estimation Based on Auto-Regressive Model in AWGN Channels 被引量:1
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作者 Dan-Ping Bai Qun Wan Xian-Sheng Guo Yan Wang 《Journal of Electronic Science and Technology of China》 2008年第1期21-24,共4页
Signal-to-noise ratio(SNR)estimation for signal which can be modeled by Auto-regressive(AR)process is studied in this paper.First,the conventional frequency domain method is introduced to estimate the SNR for the ... Signal-to-noise ratio(SNR)estimation for signal which can be modeled by Auto-regressive(AR)process is studied in this paper.First,the conventional frequency domain method is introduced to estimate the SNR for the received signal in additive white Gauss noise(AWGN)channel.Then a parametric SNR estimation algorithm is proposed by taking advantage of the AR model information of the received signal.The simulation results show that the proposed parametric method has better performance than the conventional frequency doma in method in case of AWGN channel. 展开更多
关键词 Auto-regressive model AWGN channel model information snr signal-to-noise ratio) estimation.
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Carrier Synchronization for Very Low SNR
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作者 Jun-Hui Xu Zhao Wang Zhong-Jie Gao Zhong-Pei Zhang 《Journal of Electronic Science and Technology》 CAS 2010年第2期103-107,共5页
The Turbo decoding performance will suffer serious degradation under low signal-to-noise ratios (SNR) conditions for the reason of residual frequency and phase offset in the carrier. In this paper, an improved resid... The Turbo decoding performance will suffer serious degradation under low signal-to-noise ratios (SNR) conditions for the reason of residual frequency and phase offset in the carrier. In this paper, an improved residual carrier frequency offset estimation algorithm based on a priori probability aided (APPA) phase estimation is proposed. A carrier synchronization loop that combines the iterative turbo decoder and the phase estimator together is constructed, where the extrinsic information obtained from the Turbo decoder is used to aid an iterative phase estimation process. The simulation results show that the algorithm performs successfully under very low SNR conditions (for example, less than -7.4 dB) with large frequency offset and phase error and the performance of this algorithm is very close to the optimally synchronized system. 展开更多
关键词 Index Terms- Carrier synchronization frequency offset phase error signal-to-noise ratios (snr).
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Optimizing Optical Attocells Positioning of Indoor Visible Light Communication System 被引量:1
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作者 Mohammed S.M.Gismalla Asrul I.Azmi +5 位作者 Mohd R.Salim Farabi Iqbal Mohammad F.L.Abdullah Mosab Hamdan Muzaffar Hamzah Abu Sahmah M.Supa’at 《Computers, Materials & Continua》 SCIE EI 2023年第2期3607-3625,共19页
Visible light communication(VLC),which is a prominent emerging solution that complements the radio frequency(RF)technology,exhibits the potential to meet the demands of fifth-generation(5G)and beyond technologies.The ... Visible light communication(VLC),which is a prominent emerging solution that complements the radio frequency(RF)technology,exhibits the potential to meet the demands of fifth-generation(5G)and beyond technologies.The random movement of mobile terminals in the indoor environment is a challenge in the VLC system.The model of optical attocells has a critical role in the uniform distribution and the quality of communication links in terms of received power and signal-to-noise ratio(SNR).As such,the optical attocells positions were optimized in this study with a developed try and error(TE)algorithm.The optimized optical attocells were examined and compared with previous models.This novel approach had successfully increased minimum received power from−1.29 to−0.225 dBm,along with enhanced SNR performance by 2.06 dB.The bit error rate(BER)was reduced to 4.42×10−8 and 6.63×10−14 by utilizing OOK-NRZ and BPSK modulation techniques,respectively.The optimized attocells positions displayed better uniform distribution,as both received power and SNR performances improved by 0.45 and 0.026,respectively.As the results of the proposed model are optimal,it is suitable for standard office and room model applications. 展开更多
关键词 Visible light communication(VLC) optical attocell received power signal-to-noise ratio(snr) bit error rate(BER) coefficient of variation(CV)
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Consistency in responses to conspecific advertisement calls with various signal-to-noise ratios in both sexes of the Anhui tree frog
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作者 Zhiyue Wang Haohao Ma +4 位作者 Cheng Chen Ruolei Sun Kai Liu Baowei Zhang Guangzhan Fang 《Current Zoology》 SCIE CAS CSCD 2023年第6期718-726,共9页
Environmental noise has a significant negative impact on acoustic communication in most situations,as it influences the production,transmis-sion,and reception of acoustic signals.However,how animals respond to conspec... Environmental noise has a significant negative impact on acoustic communication in most situations,as it influences the production,transmis-sion,and reception of acoustic signals.However,how animals respond to conspecific sounds when there is interference from environmental noise,and whether males and females display convergent behavioral responses in the face of noise masking remain poorly understood.In this study,we investigated the effects of conspecific male advertisement calls with different signal-to-noise ratios on male-male competition and female choice in the Anhui tree frog Rhacophorus zhoukaiyae using playback and phonotaxis experiments,respectively.The results showed that(1)female Anhui tree frogs preferentially selected the conspecific calls with higher SNR compared to calls with lower SNR;(2)males preferen-tially responded vocally to the conspecific calls with higher SNR compared to calls with lower SNR;and(3)males'competitive strategies were flexible in the face of noise interference.These results suggest that preferences of both sexes converge in outcome,and that male competitive strategies may depend on predictable female preferences.This study will provide an important basis for further research on decision-making in animals. 展开更多
关键词 advertisement call female choice male-male competition noise signal-to-noise ratio(snr)
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庐枞矿集区大地电磁测深强噪声的影响规律 被引量:64
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作者 汤井田 徐志敏 +1 位作者 肖晓 李晋 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2012年第12期4147-4159,共13页
天然大地电磁场信号微弱,极化方向随机,极易受电磁噪声污染.张量阻抗分析、远参考技术、Robust估计等对随机噪声和不相关噪声有比较好的压制效果,但对强的相关噪声目前还没有有效的压制方法.庐枞矿集区人烟稠密、工业发达,是我国著名的... 天然大地电磁场信号微弱,极化方向随机,极易受电磁噪声污染.张量阻抗分析、远参考技术、Robust估计等对随机噪声和不相关噪声有比较好的压制效果,但对强的相关噪声目前还没有有效的压制方法.庐枞矿集区人烟稠密、工业发达,是我国著名的铁、铜、硫等矿产基地之一,区内强烈的工业、通讯、矿山、民用等电磁干扰严重污染了大地电磁测深数据.本文首先根据实测的电磁场时间域波形和卡尼亚电阻率测深曲线形态,挑选出基本未受噪声污染的测点(Y1650).然后利用数学形态学从受严重污染的电磁场时间序列中提取出类方波、三角波、阶跃、脉冲和充放电5种典型噪声的波形,并以不同的方式将这些噪声波形与Y1650的电磁场波形叠加,对比分析加噪后Y1650点电阻率和相位测深曲线的变化,进而归纳出典型强噪声对庐枞大地电磁测深资料的影响规律,为进一步压制强噪声和资料处理提供依据. 展开更多
关键词 大地电磁测深 矿集区 强噪声 波形 相干度 信噪比
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小型低值LD激光测距仪的测距能力与系统的信噪比 被引量:4
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作者 张在宣 陈庆根 +2 位作者 余向东 郭宁 吴孝彪 《光子学报》 EI CAS CSCD 1998年第10期944-947,共4页
研制成一种小型、便携式、低值、对人眼安全、无合作目标的小型低值半导体LD激光测距仪.工作波长λ=905nm;测距范围14~1000m;测距精度<±1m;重复频率100Hz.有多种工作模式,具有省电功能.它的测距能... 研制成一种小型、便携式、低值、对人眼安全、无合作目标的小型低值半导体LD激光测距仪.工作波长λ=905nm;测距范围14~1000m;测距精度<±1m;重复频率100Hz.有多种工作模式,具有省电功能.它的测距能力优于国内外同类低值LD激光测距仪.LF-1激光测距仪是一种光子雷达系统.本文从光子测距方程、系统结构、信噪比分析角度。 展开更多
关键词 激光二极管 小型 激光测距仪 测距方程 信噪比
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基于光折变效应提升啁啾脉冲信噪比的光谱扫描滤波法
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作者 叶荣 张彬 +3 位作者 曾冰 孙年春 隋展 马再如 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2014年第2期293-299,共7页
基于光谱扫描滤波原理,提出了一种利用光折变效应来提高啁啾脉冲信噪比的扫描滤波方法,并进行了理论分析。针对内置光折变晶体的Fabry-Perot(F-P)标准具光谱扫描滤波装置,定量分析了其透射谱特性,详细讨论了Fabry-Perot(F-P)标准具两平... 基于光谱扫描滤波原理,提出了一种利用光折变效应来提高啁啾脉冲信噪比的扫描滤波方法,并进行了理论分析。针对内置光折变晶体的Fabry-Perot(F-P)标准具光谱扫描滤波装置,定量分析了其透射谱特性,详细讨论了Fabry-Perot(F-P)标准具两平板的反射率、透射谱窗口带宽、外加场的控制参数以及信号光啁啾率变化等对啁啾脉冲信噪比的提升及其滤波透射率的影响。结果表明,F-P两平板的反射率越高,则透射谱越尖锐,透射窗口越窄,滤波效果也就越好。为了得到有效的信噪比提升,一般要求其反射率大于0.99;外加场的控制和信号光啁啾率的变化对扫描滤波的影响较大,在实际工作中,应尽量保证外加场和啁啾率的精确控制,以确保信号光和滤波函数的同步匹配。针对中心波长800nm的啁啾信号脉冲,采用提出的光谱扫描滤波方法,对放大自发辐射(ASE)的随机噪声与预脉冲进行滤波,可得到近3个量级的信噪比提升效果。 展开更多
关键词 光谱扫描滤波 啁啾脉冲 信噪比 光折变效应 signal-to-noise ratio (snr)
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