共查询到20条相似文献，搜索用时 625 毫秒
1.
In wireless communications,mobiles emit signals that arrive at a receiver with multiple paths,each with its own direction of arrival(DOA),path delay,fading,and Doppler shift frequency,which influence the quality of communication seriously.These parameters should be taken into account in array signal processing.Based on CDMA signal,a novel Space-Time approach is proposed to estimation the DOA,time delay,and the Doppler shift frequency.Because utilize special signal model about space-time-frequency of mobile communications.The proposed algorithm has simpler structure and high quality of division.The simulation results show the feasibility and effectiveness of the method. 相似文献
2.
In many special filtering system, the direction of arrival(DOA) should be evaluated for the received signal. MUSIC algorithms is a classic one and is applied widely, but its computing load is very large because there exist many transforms of matrix. As the number of uniform circle is, the data are cyclic in the searching of peak in MUSIC algorithm for 2-D evaluation of DOA. The authors discuss how to use DFT to reduce the computation load. At the same time, the simulation of performance shows that the proposed algorithm improves the efficiency by fifty percent, that is important for the project reality. 相似文献
3.
MUSIC algorithm is often applied in direction of arrival estimation of communication signal or radar signal. But the traditional MUSIC algorithm is not applicable in the presence of the correlational signals. Combining with time average processing, an algotithm of two-dimensional space-time average is suggested on the base of space average technic especially for the DOA estimation of CDMA communication signal. A detaild analysis and a conclusion about this improved algorithm is presented. Ensuring the accurary of the estimation an efficient decrease in quantity of operation is achieved with the algorithm, so it is more suitable for real-time processing. The efficiency of the improved algorithm is attested by the emulating results. 相似文献
4.
The principle and method of the adaptive filter and the filtering with wavelet transform were analyzed, and the model and method of adaptive filtering with wavelet transforms for the transient signal was established. The separated noise of signal by the multi-scale decomposition of wavelet transforms, was the input signal of adaptive filter, and accordingly the optimal filtering method of signal-noise decomposition was realized. By the adaptive filter grou Pbased on the wavelet transform, the optimal filtering to the multi-noise of signal is achieved at the same time, and the method presented in this paper has the excellent filtering capability. Examples of application demonstrate that this method presented is excellent to realize the optimal estimate to the valuable signal and noise of the transient signal in the same frequency segment. 相似文献
5.
Zhang Zhaohui Zhu Linzhang 《保鲜与加工》1989,(6):21-27
The limitation of LMS adaptive noise cancelling (ANC ) is analyzed here. Based on the discussing of general signal and noise model of process detection control system, a fast adaptive filtering(FAF) is proposed on the basis of modelling the correlativity between the noise and it's correlative noise with the view of large noise. Fast transversal filtering ( FTF ) adaptive, algorithms is used to imitate the correlative modelling. Both simulation and experiments show that the method presented in this paper is suitable for the process detection control system , and it exhibts better results than the LMS noise cancelling method. 相似文献
6.
For high precise frequency estimation of the short sinusoid signal at low signal-to-noise ratio (SNR), a weighted fusion algorithm for frequency estimation of the short signal with the same frequency and length (SFL-Signal) is proposed. The spectrum model of SFL-Signal and the phase compensation matrix with phase coherent and noise cancellation are constructed. Secondly, the SFL-signal spectrum is weight-fused with the phase compensation matrix to obtain the result almost the same as that of the spectrum of the phase-coherent sinusoid signal. Consequently, high frequency estimation precision is obtained with spectral peak searching of the weight-fusion spectrum. Algorithm analysis and simulation results show that, compared with the existing methods,the proposed algorithm works better in term of precision, calculation complexity, noise immunity, and fits for any type of SFL-Signal. 相似文献
7.
基于GF-1卫星影像的中国冬小麦制图研究 总被引：1，自引：1，他引：0
旨在实现冬小麦面积自动化提取,本文提出一种基于冬小麦NDVI加权指数(WNDVI)的分类算法。将影像分割成标准的小区域,从而构建冬小麦分类单元,采用自适应方法确定冬小麦种植区和非种植区WNDVI分割阈值。以2013年10月至2014年5月期间的GF-1卫星WFV影像为例,构建了全国14个省（市、区）的1180个分类单元的WNDVI,实现了2014年全国主产区冬小麦种植区的空间分布图;采用14233个样本对结果进行验证精度,总体精度达到了90.6%。本方法自动化程度高,结果稳定,适合大范围冬小麦面积监测业务化运行。 相似文献
8.
In order to improve the long-playing frequency tracking ability in the signal processing for coriolis mass flowmeter (CMF) , a new IIR adaptive notch filter (ANF) is developed via steiglitz-mcBride method (SMM) and applied to filter the sensor output signal whose frequency, amplitude and phase are time-varying following the random walk model. The proposed method can detect the signal frequency fleetly and track the frequency variations continuously. The tracking performances of the proposed method and the adaptive lattice notch filter (LANF) method are investigated with computer simulations. Simulations demonstrate the superiority of the proposed method and show it has advantages of fast convergence rate, insensitivity to initial phase variations, and higher long-playing tracking stability and accuracy than LANF method. 相似文献
9.
The force feedback technology is a new kind of tele-operated robot,and it is of broad practical foreground to study in this aspect.In A novel force feedback bilateral servo system is presented through studying and analyzing traditional force feedbck control systems in this field,which regards the difference between the master's manipulative force and the master's resistance as command signal,simultaneity,the difference between the slave's displacement and the master's displacement is fed back for driving movement of the slave.The arithmetic takes on control briefness,constringency rate rapidness,real-time well,and improves dynamic characteristic of system. 相似文献
10.
Smart antenna is one of the key technique in the third generation mobile telecommunication system. Main estimation methods for DOA(direction of arrival),i.e. ESPRIT, MUSIC, WSF, Mininorm,etc., are researched,the performances for DOA estimation based on smart antenna are analyzed by the research of theory, simulation experiment and the contrast algorithms between and Cramer Rao Bound.The research results aren't only propitious to research and develop for smart antenna,but also for the application of smart antenna in mobile telecommunication. 相似文献
11.
In the course of recording heart sound, it is inevitable that many kinds of noise will be merged in the main signal. These kinds of noise disbennifit the heart sounds, even import awful influence to analysis result. So, before further processings of phonocardiographic records, noise must be suppressed. Because heart-sound is a highly nonstationary signal, this paper presents the application of adaptive filter method to the elimination of noise,and at the same time, employs the datum of heart-sound plot as the reference noise. With simulink, a modeling and simulation tool for dynamical systems, the model of LMS adaptive heart-sound enhancement is established.Tests prove this method makes effective denoising and heart-sound enhancement. 相似文献
12.
According to the theory of parameters adaptive control and variable driving, for a kind of discrete nonlinear chaotic systems, a method of chaotic synchronization is presented for different system parameters. In the equation of parameters adaptive control, control coefficients are chaotic signal. Because control coefficients are constant usually for the former parameters adaptive control, so the parameters adaptive control method is very universal, namely the former parameters adaptive control methods are special examples in our control method. Simulation results show that this method is available. 相似文献
13.
A low-complexity blind adaptive receiver for ultra-wideband (UWB) systems in the presence of both multiple access interference (MAI) and inter symbol interference (ISI) is proposed, which is composed of two stages. In the first stage, a reduced-rank algorithm based on the multi-stage Wiener filter (MSWF) is considered to suppress the MAI and extract multi-path components. Channel estimation using the projection approximation subspace tracking with deflation (PASTd) algorithm and multi-path combining are then performed to further enhance the signal to interference plus noise ratio (SINR) of the desired user in the second stage. The simulation results show that the proposed receiver exhibits reasonably good bit error ratio (BER) performance compared with those of matched filter, conventional Rake receiver, decorrelating Rake receiver and adaptive receiver based on constant modulus algorithm (CMA). Moreover, it has faster convergence speed and less complexity. 相似文献
14.
A novel scheme is present to improve the conversion accuracy of ADC. The proposed approach uses adaptive sinusoidal filter. For the measurement of the signal with given frequency, the automatic adjustment of filter coefficients is based on least mean-square error rule, which is a mathematical tool can be employed to make filter output signal achieve the best approximation to the needed one. Then based on the result, it is able to get the amplitude and phase of the measured signal accurately. MATLAB software is used to verify the effectiveness of the algorithm. It proves that adaptive filter has improved the accuracy and signal-to-noise ratio of ADC, which is equal to increase the conversion digits. 相似文献
15.
基于GIS的地市级人工影响天气作业指挥系统设计与实现 总被引：2，自引：1，他引：1
人工影响天气作业活动在各级气象部门广泛开展。传统的工作模式中,地市级人工影响天气作业主要依托指挥人员手工分析资料后,通过口头传递和手写记录的方式完成指令的下达和反馈。随着近几年人影作业规模迅速扩大,传统的作业模式已经不能适应人工影响天气业务的现代化建设需要。为了进一步提高工作效率,三门峡市气象局基于GIS开发了1套地市级人工影响天气作业指挥系统。该系统由软件和硬件2个部分组成。其中,指挥系统软件通过气象局内部网络实时获取气象观测资料和雷达、卫星等产品资料,经过一系列的数据处理后,采用GIS技术实现气象数据与地理信息在指挥平台中的叠加显示,为作业指挥人员提供决策气象数据支持。并根据预先设定条件为炮点作业人员生成详细的作业参数,将作业指令通过手机短信、电子显示屏、语音大喇叭等方式传递给一线作业人员,具有较强的作业指导性和调度实时性。系统硬件主要包括用于辅助指挥的地理沙盘模型和手机、语音大喇叭、LED电子显示屏等指令接收终端,指令接收终端通过GPRS网络连接到系统服务器上。该系统已经在三门峡市气象局和所辖县气象局投入业务应用,在运行过程中稳定可靠、指令接收及时,有效地提高了工作效率,达到了预定的设计目标。 相似文献
16.
GIS技术在人工影响天气作业气象探测资料分析中的应用 总被引：2，自引：2，他引：0
笔者以焦作市人工影响天气作业指挥系统为实例,分析了气象探测资料在人工影响天气作业指挥中的综合处理应用,介绍了组件式GIS技术在人影作业指挥系统中应用的总体思路,并阐述了该系统中GIS应用的主要方面,包括离散点探测资料的分析处理、雷达资料处理显示、各类探测资料的融合叠加、精细化预报产品的图形化显示及火箭安全射击范围管理、区域协作区管理等。实现了人工影响天气作业指挥中气象探测数据、预报预警信息、火箭射击区域等数据的空间管理,基于GIS可以对作业效果进行科学评估。 相似文献
17.
Computer simulation of a selection strategy to accommodate genotype environment interactions in a wheat recurrent selection programme 总被引：2，自引：0，他引：2
Multi-environment trials (METs) are used in plant breeding programmes to evaluate genotypes (lines/families) as a basis for selection on expected performance (yield and/or quality) in a target population of environments (TPE). When a large component of the genotype environment (G × E) interactions results from crossover interactions, samples of environments in METs that deviate from the TPE provide a suboptimal basis for selection of genotypes on performance expected in the TPE. To adjust for the negative effects of these deviations, a selection strategy that weights the data from the MET according to their expected frequency of occurrence in the TPE (i.e. a weighted selection strategy) was investigated. Computer simulation methodology was used to obtain preliminary information on the weighted selection strategy and compare it to the traditional unweighted selection strategy for a range of MET scenarios and G × E interaction models. The evaluation of the weighted selection strategy was conducted in context with the germplasm enhancement programme (GEP) of the Northern Wheat Improvement Programme in Australia. The results indicated that when the environments sampled in the MET matched those expected in the TPE, the unweighted and weighted selection strategies achieved a similar response to selection in the TPE. However, when the environments sampled in the MET did not match the expectations in the TPE and a large component of the G × E interactions resulted from crossover interactions, the weighted selection strategy achieved a greater response to selection in the TPE. The advantage of the weighted strategy increased as the amount of crossover G × E interaction increased or fewer environments were sampled in the METs. 相似文献
18.
自适应加权最小二乘支持向量机的空调负荷预测 总被引：1，自引：0，他引：1
为了提高建筑空调负荷的预测精度,在分析空调负荷主要影响因素的基础上提出了一种基于自适应加权最小二乘支持向量机(AWLS-SVM)的建筑空调负荷预测方法。该方法根据预测误差的统计特性,采用基于改进正态分布加权规则,自适应地赋予每个建模样本不同的权值,以克服异常样本点对模型性能的影响。建模过程中采用粒子群优化(PSO)算法对模型参数进行优化,以进一步提高模型预测精度。基于DeST模拟数据将AWLS-SVM方法应用于南方地区某办公建筑的逐时空调负荷预测中,并与径向基神经网络(RBFNN)模型、LS-SVM模型及WLS-SVM模型作比较,其平均预测绝对误差分别降低了51.84 %、13.95 %和3.24 %,并进一步基于实际空调负荷数据将该方法应用于另一办公建筑的逐日空调负荷预测中。预测结果表明：AWLS-SVM预测的累积负荷误差为4.56 MW,亦优于其他3类模型,证明了AWLS-SVM具有较高的预测精度和较好的泛化能力,是建筑空调负荷预测的一种有效方法。 相似文献
19.
The mass flowrate of Coriolis mass flowmeter in practical application has slow changes with time. To solve the problem, an improved time-varying signal model whose frequency, amplitude and phase are time-varying based on the random walk model is established firstly. A new algorithm of adaptive notch filter with the capability of tracking frequency variation is applied to filter the sensor output signal of Coriolis mass flowmeter and its frequency is calculated next. An adaptive line enhancer based on the mentioned notch filter extracts fundamental frequency signal from noisy data. Then, by short window intercepting, the revised sliding DTFT recursive algorithm is introduced to calculate the real-time phase difference between two enhanced signals. With the frequency and phase difference obtained, the time interval between the two signals is calculated and then the mass flowrate is derived. The simulations and field test results show that the proposed method can not only track the change of frequency and phase, but also ensure the calculation accuracy when measuring small phase difference. The computational load of the algorithm is simple so that it can be applied to real-time signal processing for Coriolis mass flowmeter. 相似文献
20.
本研究以河西走廊荒漠绿洲边缘关键天然固沙植物沙拐枣为研究对象,对流动沙丘、固定沙丘不同生境的沙拐枣种群扩张特征进行调查,旨在更全面地认识其种群扩张特征和对干旱高温环境的适应对策。结果表明：（1）沙丘不同生境,沙拐枣种群扩张方式存在显著差异：在流动沙丘,丘间低地和过渡带以有性繁殖为主,无性繁殖为辅;迎风坡和背风坡以无性繁殖为主;而随着流动沙丘固定,种群以有性繁殖为主,无性繁殖数量和所占比重显著下降,并导致种群数量下降。（2）不同生境中沙拐枣种群密度与年龄均呈显著负相关,种群以幼龄苗为主,种群最大年龄出现在丘间低地,为36龄。（3）流动沙丘不同生境根状茎主要为2年生,多年生根状茎长度较短;而固定沙丘不同生境根状茎年龄结构较为均衡。 相似文献