FPGA implementation of high-performance,resource-efficient Radix-16 CORDIC rotator based FFT algorithm

The fast Fourier transform (FFT) is an algorithm widely used to compute the discrete Fourier transform (DFT) in real-time digital signal processing. High-performance with fewer resources is highly desirable for any real-time application. Our proposed work presents the implementation of the radix-2 decimation-in-frequency (R2DIF) FFT algorithm based on the modified feed-forward double-path delay commutator (DDC) architecture on FPGA device. Need for a complex multiplier to carry out the multiplication of complex twiddle factors and large memory to store the twiddle factors are the main concerns for FFT implementation. Propose work aims to address these issues. In this work, a high-performance radix-16 COordinate Rotational DIgital Computer (CORDIC) algorithm based rotator is proposed to carry out the complex twiddle factor multiplication. Further, CORDIC needs only rotational angles to carry out complex multiplication, which reduces the need for large memory to store the twiddle factors. To compute the total rotation for n-bit precision, our proposed radix-16 CORDIC algorithm takes n/4 iteration as compared to n iteration of the radix-2 CORDIC algorithm. Our proposed architecture of the radix-2 decimation-in-frequency (R2DIF) algorithm is implemented on a Virtex−7 series FPGA. Further, the detailed comparison is presented between our proposed FFT implementation and other recently proposed FFT implementations. Experimental results suggest that proposed implementation has less latency and hardware utilization as compared to recently proposed implementations.     

Looking ahead: Joint small group detection and tracking in crowd scenes

Small group detection and tracking in crowd scenes are basis for high level crowd analysis tasks. However, it suffers from the ambiguities in generating proper groups and in handling dynamic changes of group configurations. In this paper, we propose a novel delay decision-making based method for addressing the above problems, motivated by the idea that these ambiguities can be solved using rich temporal context. Specifically, given individual detections, small group hypotheses are generated. Then candidate group hypotheses across consecutive frames and their potential associations are built in a tree. By seeking for the best non-conflicting subset from the hypothesis tree, small groups are determined and simultaneously their trajectories are got. So this framework is called joint detection and tracking. This joint framework reduces the ambiguities in small group decision and tracking by looking ahead for several frames. However, it results in the unmanageable solution space because the number of track hypotheses grows exponentially over time. To solve this problem, effective pruning strategies are developed, which can keep the solution space manageable and also improve the credibility of small groups. Experiments on public datasets demonstrate the effectiveness of our method. The method achieves the state-of-the-art performance even in noisy crowd scenes.     

一种移动电视直放站回波抵消的实现方法

回波(回声)抵消是数字直放站的一项关键技术,利用重发信号实现了基于自适应算法的回波信道估计以及回波抵消。仿真实验证明效果较好,并可满足数字直放站的实时性。     

二维图像放大方法的熵分析

对最近邻插值法、线性插值法、邻域像素交换法3种二维图像放大方法的熵进行了分析,给出了放大到4倍和9倍时的计算方法,并对误差进行了分析,仿真结果证明了所给方法的有效性,并发现线性插值法要好一些。     

GPS接收机多径抑制算法研究

研究了窄相关、多径估计延迟锁相环算法(MEDLL)和基于斜率估计(ELS)的GPS接收机多径抑制算法,重点研究了ELS算法,该算法可以在一定的预相关带宽的前提下,通过对相关峰两边的斜率进行估计,达到抑制多径造成的跟踪误差的效果。仿真结果表明,ELS的算法在性能上比窄相关技术更好,接近于MEDLL算法。该算法相对于窄相关技术资源规模增加不大,比MEDLL算法资源规模和计算量都要小很多,易于在硬件上实时实现。     

基于波数域积分的人体表面微波三维成像算法研究

该文给出了人体表面微波3维成像所需要满足的采样准则,提出了基于波数域积分3维成像处理方法,该方法通过在给定距离单元上沿波传播方向上的波数域积分代替了复杂的3维STOLT插值。通过计算机仿真给出了由点目标组成的人体模型的3维重建图像,利用通用仪器构建的人体微波3维成像实验系统开展童装模特的微波暗室Ka波段3维成像实验,验证了成像处理方法的正确性和有效性。     

面向区域目标的遥感卫星任务规划算法

面向区域目标的遥感任务规划问题主要解决如何在多遥感卫星条件下,对区域目标进行合理的任务分解和分配。提出了一种动态划分方法,通过加入卫星观测范围因素,改进了现有的静态划分方法。该方法划分生成的候选条带数量大大增加,使算法求解难度增大。基于邻域搜索思想,综合贪婪规则、随机模式和变邻域等因素提出了快速求解区域目标任务规划问题的贪婪随机变邻域搜索算法。最后通过实例进行了验证,结果证明应用该算法能较快得到比较好的解。     

基于视觉引导的工业机器人快速分拣系统研究

将三菱RV-13F工业机器人与视觉引导技术相结合应用于目标分拣。对原始图像进行滤波处理后再利用ORB算法实现对目标物体的快速检测,并利用最佳匹配特征点计算出目标物体的像素坐标和旋转角度。实验结果表明：计算坐标与实际坐标在X、Y坐标上的误差在1mm之内,可以保证工业机器人准确地运动到目标物体的上方,Z坐标上的误差在3mm之内,可以保证能将目标物体抓取到,快速地完成分拣任务。     

RS（255，247）译码器的FPGA实现

RS码是差错控制领域中一类重要的线性分组码,由于其出众的纠错能力,因而被广泛地应用于各种差错控制系统中,以满足对数据传输通道可靠性的要求。利用现场可编程门阵列（FPGA）技术由VHDL语言来实现RS（255,247）译码方案并应用于一种大容量的存储设备以提高数据传输和存储的可靠性。对所设计的硬件系统在ISE10．1平台上用VHDL进行了行为仿真和时序仿真,并给出了仿真波形图。     

公开密钥型数字签名的保密技术研究

RSA是目前公认的在理论和实际应用中最为成熟和完善的一种公钥密码体制,不仅可以进行加密,还可以用来进行数字签名和身份验证,是公钥密码体制的代表。对RSA数据加密算法在数字签名中的应用作了详细的分析,对RSA算法做了全面的讨论,大数模幂乘运算是实现RSA等公钥密码的基本运算,其运行效率决定了RSA公钥密码的性能,主要研究了各种模幂算法的快速实现方法,对其中某些环节做了适当的改进。