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 共查询到10条相似文献，搜索用时 15 毫秒
1.
提出了一种基于卡尔曼滤波的TOA估计算法,充分利用了卡尔曼滤波的预测功能,以预测值为中心对接收信号进行加窗处理,对此窗口内的接收信号作主成份分析得到测量值,然后对预测值进行修正.实验结果表明,与传统的TOA估计算法相比,该算法不仅使信噪比提高了约8～12 dB、均方误差降低了3～4个数量级,而且更便于实时实现.  相似文献   

2.
提出了一种利用软件算法来自适应地实现数字锁定放大器的微弱正弦信号的检测,即利用稀疏分解的匹配追踪算法来实现这种检测方法.将稀疏分解中原子库的原子(即具有随机性的频率和初始相位的正弦波)作为参考信号,利用匹配追踪算法来搜索原子库(由多个原子组成)中的最优原子-即与输入有用信号最匹配相干的原子并可以得到该最优原子的幅度,由该最优原子的幅度、频率和初始相位信息就可以估计得到输入有用信号的对应参数,从而检测估计出输入信号中的有用正弦信号.该方法无需人工调节参考信号的幅度、频率和初始相位,只需修改算法中的某些参数即可实现微弱信号检测,在应用中就会更加方便、灵活.计算机模拟表明,可以精确地检测出带噪信号中有用的正弦信号和调幅AM信号,并且在-40 dB以下极低信噪比环境下还可以同时检测出多个被强噪声淹没的有用正弦信号.
Abstract：
The paper proposes a method which realizes adaptively weak sinusoidal signal detection of digital lock-in amplifier by software algorithm.The detection method is realized by matching pursuit(MP)algorithm of sparse decomposition.In the method,an atom of atoms of MP algorithm is a reference signal,and the atom is a sinusoidal wave which possesses random frequency and the initial phase,then it uses MP algorithm to search the optimal atom of atoms and obtains its amplitude,that is to say,the optimal atom is the atom of most matching correlation with a useful input signal,so it can estimate the corresponding parameters of the useful input signal through the messages of amplitude,frequency and the initial phase of the optimal atom and detect useful sinusoidal signal of the input one.With this method,it is not necessary to manually adjust the amplitude,frequency and the initial phase of the reference signal,and what is needed is only to modify some parameters of the algorithm to realize detection of weak signals.It is more convenient and flexible in the application.Computer simulation showed that this method can accurately detect useful sinusoidal signals and AM signals of the noise signals and it can detect multiple useful sinusoidal signals in a strong noise environment of the very low SNR of-40 dB.  相似文献   

3.
Because of the ignored items after linearization, the extended Kalman filter (EKF) becomes a form of suboptimal gradient descent algorithm. The emanative tendency exists in GPS solution when the filter equations are ill-posed. The deviation in the estimation cannot be avoided. Furthermore, the true solution may be lost in pseudorange positioning because the linearized pseudorange equations are partial solutions. To solve the above problems in GPS dynamic positioning by using EKF, a closed-form Kalman filter method called the two-stage algorithm is presented for the nonlinear algebraic solution of GPS dynamic positioning based on the global nonlinear least squares closed algorithm--Bancroft numerical algorithm of American. The method separates the spatial parts from temporal parts during processing the GPS filter problems, and solves the nonlinear GPS dynamic positioning, thus getting stable and reliable dynamic positioning solutions.  相似文献   

4.
考虑在传感器网络中重构混沌信号的问题.各传感器同时观测一个混沌信号.由于带宽受限,各传感器量化观测信号并将量化后的数据发送到融合中心,该中心使用无先导卡尔曼滤波算法重构观测的混沌信号.为了节省能量,只有观测信号信噪比高于某个阈值的传感器被选中并发送数据.定义代价函数关联重构性能和能量消耗,分析并仿真了代价函数和阈值之间的关系.结果表明在某些情况下部分传感器发送数据更合理.
Abstract：
The problem of reconstructing chaotic signals in wireless sensor networks is considered.All sensors observe a common chaotic signal.Because of the limited bandwidth,the observations are quantized and the quantized data are sent to a fusion center.The fusion center reconstructs the chaotic signals by using the unscented Kalman filtering(UKF)algorithm.To save energy,only the sensors for which the SNR of the observation is higher than a threshold are chosen for transmission.A cost function is defined to relate the reconstruction performance and the energy consumption.The relationship between the cost function and the threshold is analyzed and simulated.The results show that under certain conditions,it is more reasonable that only a portion of the sensors transmit data.  相似文献   

5.
The dimension number of the centralized Kalman filter (CKF) for the rapid transfer alignment (TA) is as high as 21 if the aircraft wing flexure motion is considered in the rapid TA. The 21-dimensional CKF brings the calculation burden on the computer and the difficulty to meet a high filtering updating rate desired by rapid TA. The federated Kalman filter (FKF) for the rapid TA is proposed to solve the dilemma. The structure and the algorithm of the FKF, which can perform parallel computation and has less calculation burden, are designed.The wing flexure motion is modeled, and then the 12-order velocity matching local filter and the 15-order attitud ematching local filter are devised. Simulation results show that the proposed EKE for the rapid TA almost has the same performance as the CKF. Thus the calculation burden of the proposed FKF for the rapid TA is markedly decreased.  相似文献   

6.
This paper presents an in-flight alignment technique for a strapdown inertial navigation system (SINS) and employs a star pattern recognition procedure for identifying stars sensed by a CCD electrooptical star sensor.Collinearity equations are used to estimate sensor frame star coordinates and the conventional least square differential correction method is used to estimate the unknown orientation angles. A comparison of this attitude with the attitude estimated by the SINS provides axis misalignment angles. Simulations using a Kalman filter are carried out for an SINS and the system employs a local level navigation frame. The space stabilized SINS is discussed in conjunction with the celestial aiding. Based on the observation of the Kalman filter, the estimating and compensating gyro errors, as well as the position and velocity errors caused by the SINS misalignments are calibrated by celestial attitute information.  相似文献   

7.
A vehicle navigation and monitoring system integrated by a high precision navigation system and a vehicle black box is studied to satisfy the demand for the intelligent transportation system (ITS). Firstly, the architecture of the system is proposed. Then the integration scheme of global positioning system/dead reckoning/bluetooth beacon/map matching (GPS/DR/BB/MM) with the hluetooth assistant positioning technology, and the algorithm of the Kalman filter for the integrated GPS/DR are investigated. Finally many field trials for principle prototypes are made. Experimental results show that the proposed integrated navigation algorithm is effective and feasible, and the function of the vehicle black-box is realized.  相似文献   

8.
改进的基于模糊C-均值聚类的图像分割算法   总被引：1，自引：0，他引：1  
为了提高图像分割算法的抗噪声性能,提出了一种改进的基于模糊C-均值聚类的图像分割算法.该算法首先根据邻域像素的隶属度矩阵来计算出像素和聚类中心的空间距离,然后利用空间距离和欧氏距离来重新确定像素和聚类中心的距离,最后利用新提取的距离特征和改进的FCM聚类算法对图像进行分割.实验结果表明,该算法能有效地提取目标图像,对噪声具有较强的鲁棒性,收敛速度快.
Abstract：
To enhance the noise immunity performance of the image segmentation algorithm, an improved algorithm for image segmentation based on fuzzy C-means clustering is proposed in this paper. The spatial distance between a pixel and the cluster center is calculated by the membership matrix of the neighboring pixels, and a new distance is determined by the spatial distance and the Euclidean distance. This new distance feature and the improved algorithm based on fuzzy C-means clustering are used in image segmentation. The experimental results show that the proposed algorithm is effective in getting the target image,more robust to the noises and faster than the conventional fuzzy C-means (FCM) algorithm.  相似文献   

9.
Haigh‘s algorithm is a fundamental method for searching ESSs of linear ESS-models.In this paper ESSs are characterized by submatrices of the pay-off matrix,Then Haigh‘s algorithm has been improved in the following aspects:1) Some Esss may be overlooked when Haigh‘s algorithm is used for searching ESSs.The improved algorithm eliminates this shortage.2) The improved algorithm is eapecially favourable to computers.It is valid when the pay-off matrix is stable.  相似文献   

10.
提出一种改进型LLR BP算法,它能通过调整变量节点信息的迭代过程来降低变量节点之间信息的相关性.仿真结果表明改进型LLR BP算法比LLR BP译码算法、Normalized BP算法以及Offset BP算法具有更好的LDPC译码性能.
Abstract：
The Tanner graph of long LDPC codes usually has no loops and LLR BP algorithm is the best soft-decision decoding algorithm. But the Tanner graph of short LDPC codes usually has loops, so infor-mation within variable nodes doesn't satisfy the condition of independent identical distribution and the de-coding performance of LLR BP algorithm will decrease. In this paper, a modified LLR BP algorithm is pro-posed, which can reduce the relativity of information within variable nodes by adjusting the iterative process of variable nodes information. Simulation results show that the LDPC decoding performance of the modified LLR BP algorithm is more effective than that of LLR BP algorithm, Normalized BP algorithm and offset BP algorithm.  相似文献   

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