基于改进广义回归神经网络和主成分分析的宽带DOA估计

为了获取较高的宽带信号的DOA(direction-of-arrival)估计精度,提出了基于改进的广义回归神经网络(IGRNN,improved generalized regression neural network)和主成分分析(PCA,principalcomponent analysis)的宽带DOA估计算法。选用PCA方法对训练样本进行降维,以降低神经网络的复杂度;利用粒子群算法优化GRNN的参数;根据选取不同的聚焦角度确定粗估计、精估计的训练模型,通过粗估计得出目标的大致方位后,利用精估计模型得出最终的估计结果,避免了聚焦角度对估计精度的影响。仿真结果表明,本文提出的算法具有较好的估计精度和较高的工作效率。     

Application of DFT In the 2-D DOA Evaluation of MUSIC

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.     

基于传感和信息采集的自主导航免耕播种机设计

为了提高免耕播种机的自动化程度,设计了一款新的具有自主导航和路径规划功能的免耕播种机。该播种机能够很好地估算出入射信号的个数和方向,克服了传统定位精度低的缺点,可以有效解决密集信号环境中多个辐射源的高分辨率、高精度测向定位问题。为了验证免耕播种机的性能,对使用DOA估计信号后的播种机进行了性能测试。测试发现:其播种误差要明显小于单纯使用最小二乘法和双曲线测量法,播种合格率最高达到了98.7%,变异系数最低为1.35%,播种的精确性和稳定性较高。通过对比传统播种机和本文设计播种机的播种时间,本文设计的播种机播种时间有所缩短,播种效率有了大幅度的提高,免耕播种性能好,可以在自动化播种作业中进行推广。     

Direction of Arrival Estimation for CDMA Communication Signal

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.     

Joint Parameters Estimation for CDMA Signals

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.