数字正射影像图的调色方法与技巧

主要介绍了数字正射影像图的调色方法及在调色过程中的几个技巧,为今后进一步提高数字正射影像图的色彩质量,给客户提交高质量的影像图产品提供了良好的经验。     

PERFORMANCE IMPROVEMENT FOR A WCDMA RADIO OVER FIBER SYSTEM USING DIGITAL PRE-DISTORTER

In this paper,a Radio Over Fiber (ROF) system with a Digital Pre-Distorter (DPD) for WCDMA signal transmission is investigated.A Look-Up Table (LUT) based DPD and a Memory Polynomial (MP) DPD are appli...     

FPGA高性能查找表的设计与实现

从电路角度探讨了查找表(LUT)实现原理,基于双相不交叠时钟,设计实现了一种LUT,能高效地完成移位寄存器与RAM的功能扩展。基于SMIC0.25μmCMOS工艺优化设计了对应的版图,给出了相应的HSPICE仿真结果。此电路结构增强了逻辑块的性能,提高了FPGA的整体效率与灵活性,已被应用于FPGA的设计中。     

LUT尺寸对FPGA面积和延迟影响的理论分析

在分析隔离岛式FPGA结构的基础上,提出了基于LUT的面积和延迟模型,用于分析LUT尺寸对FPGA面积和性能的影响.结果表明利用计算模型得到的最佳LUT尺寸与实验结论一致:4-LUT获得最好的面积有效性,5-LUT获得较好的延迟.     

线性功放中数字预失真方法的实验研究

对数字预失真线性功放中两种主要的数字预失真方法:多项式拟合法和查找表构建预失真器法进行研究;首先针对两种方法所对应的不同预失真器结构,就预失真精度、算法复杂性、所需存储空间和自适应能力等进行分析对比;然后采用cdma2000调制信号源对两种方法预失真效果作ADS仿真分析和实验测试,验证了两种方法的可行性,并对两种方法预失真能力作进一步讨论;最后总结了两种预失真方法在功放线性化应用的优缺点和适用范围.     

Dynamic Look-Up-Table-Based Maximum a Posterior Probability Algorithm

In this paper, a Look-Up-Table (LUT) based calculation for implementing log-likelihood ratio (LLR) of the Maximum a Posterior (MAP) decoder is introduced and analysed. In the region of low signal to noise ratio, the analysed performances of turbo coding have been found very satisfying. However, when implementing the MAP turbo decoder, the required calculation for LLR is too complex prohibiting its applications. In order to reduce the complexity a dynamic-LUT based simplification is proposed whereas a static-LUT never converge the expectations, since the limited size and resolution of LUT dramatically degrade the performance. In order to maintain simplicity for a high performance implementation, a dynamic LUT, which has partial resolutions in separate decision regions and being re-calculated for further iterations of decoding, is proposed. One of the most important results obtained is that our proposed dynamic-LUT based MAP algorithm removes “ln(·)” process, which is the natural logarithm in LLR’s calculation. Therefore, it reduces high computational complexity in the MAP algorithm with some reasonable performance degradations.

基于改进的DA算法实现高阶FIR滤波器

介绍了几种应用于高阶FIR滤波器的算法,着重介绍DA算法,该算法主要基于LUT形式,从根本上减少了乘法器资源的消耗,提高了系统的实时性。并以此为基础介绍了几种改进的算法,分别是基于LUT分解、基于OBC编码以及基于双向选择器的DA改进算法,这些算法都从不同程度上降低了资源的使用,提高了信号处理速度,降低了系统复杂性。最后,对FIR滤波器的改进算法进行了全面的分析比较和仿真,仿真结果均正确并且符合设计要求。     

基于FPGA实现的任意波形产生器

介绍了DDS的原理和FPGA的特点，并在此基础上描述了基于FPGA的DDS的硬件和软件设计方案。     

Efficient radiative transfer model inversion for remote sensing applications

A simple method for efficient inversion of arbitrary radiative transfer models for image analysis is presented. The method operates by representing the shape of the function that maps model parameters to spectral reflectance by an adaptive look-up tree (ALUT) that evenly distributes the discretization error of tabulated reflectances in spectral space. A post-processing step organizes the data into a binary space partitioning tree that facilitates an efficient inversion search algorithm. In an example shallow water remote sensing application, the method performs faster than an implementation of previously published methodology and has the same accuracy in bathymetric retrievals. The method has no user configuration parameters requiring expert knowledge and minimizes the number of forward model runs required, making it highly suitable for routine operational implementation of image analysis methods. For the research community, straightforward and robust inversion allows research to focus on improving the radiative transfer models themselves without the added complication of devising an inversion strategy.     

基于查找表LUT结构的奇数与小数分频电路设计

基于查找表LUT的原理,提出了奇数与小数分频电路的设计原理,并采用Verilog进行了奇数与小数分频电路的描述,使用Synopsys公司的Design Complier和Astro进行了综合与布局布线,得到了所设计奇数与小数分频电路的版图,然后仿真证明了设计方法的正确性.