基于DUC的ISAR图像欺骗干扰技术

针对宽带线性调频体制雷达,介绍了一种图像欺骗干扰信号的实现方法。通过分析雷达回波去斜率解调原理,得到图像欺骗干扰信号的特征表达式。然后采用正交数字上变频（DUC）技术进行基带信号数字域调制和频率变换。经过高性能频谱仪和成像软件分析,证明了该干扰算法能产生具有欺骗效果的图像（400点×400点）。     

一种数字存储示波器显示电路的设计与应用

为了满足高性能数字存储示波器波形显示的稳定性,介绍了以双口RAM IDT-70T3539M和EP1C4F324C8为主要器件搭建的数字存储示波器显示控制电路方案,详细讨论了 FPGA 内部各功能模块和液晶显示相关驱动程序的编写。与原显示方案相比,此方案更能满足示波器波形显示的各项性能指标要求。该显示方案实现了波形更新率为每秒2 000波形,支持分辨率为640×480和18 bit色的TFTLCD,并可实现多种显示方式。     

一种数字宽带截获接收机的高效实现

针对高密度复杂信号环境下的雷达信号截获问题,研究并实现了一种数字宽带实时接收方法。该方法工作在超外差体制下,在宽带中频数字化信号后,利用多相滤波器进行高效信道化,并对各子信道参数测量,然后通过简单的检测和判决逻辑实现多路信号截获。在MATLAB和FPGA上,对500MHz宽带信号进行了8路信道化接收、参数测量、检测判决实现。仿真和硬件实现结果均表明,在一定的信噪比和信号频率间隔下,实现的接收机能够对多个同时到达信号进行实时侦察与测向。     

基于三维DCT变换的体数据鲁棒 数字水印嵌入算法

本文基于三维离散余弦变换(3D-DCT)技术和扩频通信技术提出三维体数据鲁棒水印嵌入算法.算法将原始的二值图像水印利用扩频通信技术生成可以直接嵌入的体水印信息;分别对体水印信息和原始的体数据进行分块离散余弦变换,在变换域内实现水印嵌入.该算法嵌入的水印信息具有不可见性,能够抵抗剪切、加噪、滤波、旋转等常见攻击.仿真实验验证了算法的有效性.     

Suppressing the charged coupled device noise in univariate thin-layer videoscans: A comparison of several algorithms

The digital processing of chromatographic thin-layer plate images has increasing popularity among last years. When using a camera instead of flatbed scanner, the charged coupled device (CCD) noise is a well-known problem—especially when scanning dark plates with weakly fluorescing spots. Various techniques are proposed to denoise (smooth) univariate signals in chemometric processing, but the choice could be difficult. In the current paper the classical filters (Savitzky–Golay, adaptive degree polynomial filter, Fourier denoising, Butterworth and Chebyshev infinite impulse response filters) were compared with the wavelet shrinkage (31 mother wavelets, 3 thresholding techniques and 8 decomposition levels). The signal obtained from 256 averaged videoscans was treated as the reference signal (with noise naturally suppressed, which was found to be almost white one). The best choice for denoising was the Haar mother wavelet with soft denoising and any decomposition level larger than 1. Satisfying similarity to reference signal was also observed in the case of Butterworth filter, Savitzky–Golay smoothing, ADPF filter, Fourier denoising and soft-thresholded wavelet shrinkage with any mother wavelet and middle to high decomposition level. The Chebyshev filters, Whittaker smoother and wavelet shrinkage with hard thresholding were found to be less efficient. The results obtained can be used as general recommendations for univariate denoising of such signals.     

数字水准仪自动读数方法研究

数字水准仪具有精度高、速度快、操作方便等优点,在测量、大型工程施工建设、工业设备安装、地壳形变监测、科学研究等需要高精度高程信息的领域得到了广泛地应用.文章针对如何实现自动读数问题,设计了基于自动安平水准仪的数字水准仪的方案,建立了测量试验系统,完成了编码水准尺图像的识别、测量读数方法的设计与实现.     

Multi-policy threshold signature with distinguished signing authorities

Threshold signature plays an important role to distribute the power of a single authority in modern electronic society.In order to add functions and improve efficiency of threshold signatures,a multi-policy threshold signature scheme with distinguished signing authorities is proposed.In the scheme two groups can sign and verify each other,so the scheme is two-way signing and verifying.Moreover,the threshold values of the two groups can change with the security classification of the signing document,every discretionary signatory only signs a small part of the document instead of the whole one,so the bandwidth of data transmission for group signature construction can be reduced and the size of group signature is equivalent to that of any individual signature.     

一种数字功放电路设计应用

在很多个人计算机PC或小家电音响数字功放设计中，电源部分由市电AC220V经整流、滤波和稳压电路等处理后供给，电路复杂，而且体积大而重。本方案音响功放采用了SWITCH—MODE POWER SUPPLY，使得供电变的简单灵活更实用。种低成本，低功耗，体积小，效率高，设计灵活使用方便的数字功率放大技术。存功能模块上主要有：供电部分，信号输入部分、信号处理，功率放大部分、输出部分最后由扬声器或喇叭输出的解决方案。     

基于DSP的数字控制功率因数校正

相对于传统的模拟控制技术。采用数字控制技术的PFC具有显著的优点。文中讨论了采用数字信号处理器(DSP)作为控制核心时PFC主电路参数的选择，并详细讨论了两种数字PID调节器参数的确定方法。最后在Simulink中仿真得到了较理想的波形。