一种基于STFT的数字信道化方法

数字信道化接收机是电子战中应用最广泛的一种宽带侦察接收机.将短时傅里叶变换（STFT）与数字信道化相结合,阐述了基于STFT的信道化原理,通过Matlab仿真验证了该方法的正确性和可行性以及信号时频参数测量和分辨多信号的能力.     

基于启发式蚁群算法的高保真信号重构

在当前的雷达射频半实物仿真系统应用中,有源干扰信号和雷达目标回波信号的模拟主要通过宽带数字射频存储技术(DRFM)实现。随着雷达瞬时工作带宽和捷变频范围的增大,如何实现对超宽带雷达信号的高保真重构是实际工程中面临的重要难题。文中基于启发式蚁群算法,结合数字信道化思想,实现了在现有有限的硬件平台基础上,对超宽带雷达信号的高精度重构。最后,通过仿真和实验验证了该方法的有效性。     

宽带数字信道化接收机在FPGA中的实现

在分析数字信道化原理的基础上,提出一种新的数字信道化接收机技术,较好地解决了宽带数字信号实时处理、信道化接收机中邻近信道响应及高精度脉冲描述字（PDW）形成等技术问题,在FPGA中进行了宽带数字接收机设计综合及仿真。结果验证了实时宽带数字处理思路及其在FPGA中实现的正确性,为宽带数字接收机的实时处理提供了一种新的技术途径,具有广阔的应用前景。     

基于多相滤波的宽带数字信道化处理在被动探测中的应用

介绍了基于多相滤波的宽带数字信道化处理技术。对宽带信号进行信道化处理,并对信道化后的数据进行了信号处理,给出了仿真结果。仿真结果表明该方法高效、灵活,易实现。     

基于动态信道化的雷达与雷达对抗侦察一体化接收技术

针对雷达接收机和雷达对抗侦察接收机存在的不同特征,提出了基于动态信道化的雷达与雷达对抗侦察一体化接收技术。首先利用余弦调制滤波器组将中频带宽分解为若干子带,再通过频谱感知和子带合并实现非均匀动态信道化,最后利用非均匀动态信道化技术分别接收雷达回波信号和辐射源直达波信号。为了满足一体化接收机的瞬时动态范围、灵敏度、监视带宽以及频率分辨率等性能指标的要求,本文引入一种大M值高阻带衰减原型滤波器设计方法。理论分析和仿真实验验证了该一体化接收技术的有效性。     

宽带数字信道化EDA设计

数字信道化接收机具有高截获概率和处理灵活的特点,设备体积小巧,是未来通信对抗接收机的发展趋势之一。基于低通滤波器组的数字信道化实现方法,构建了优化的数字信道化实现方法。使用Matlab仿真工具箱Simulink及Xilinx集成设计工具System Generator实现了对信道化接收机从系统到底层硬件设计的全流程仿真设计,对工程的系统设计具有一定的指导意义。     

Research of sub-channel filter technique in the digital channelization

In the satellite communications,there were very high performance requirements for the satellite transponder due to the restrictions of the volume and weight of the load,and the satellite channelization technique was an important means to solve this problem.The overall implementation structure and the sub-channel filter design method which played a serious role in the system were discussed.It has important practical significance to the overall implementation of the digital channelization.     

美国基西米河生态修复工程的经验

美国佛罗里达州基西米河1962～1971年的河道渠化工程,将本来蜿蜒的天然河流变成了几段近似直线的人工运河,提高了河道的排洪能力,但同时也对河流生态环境造成了严重的负面影响。为了恢复河流原有的生态面貌,进行了一系列的生态修复试验,包括改变上游水库的运用方式,塑造具有季节性变化的来流条件;修建拦河坝,人为抬高水位以恢复两岸的湿地;回填被渠化的河道,恢复其自然蜿蜒状态。基西米的经验告诉我们,在利用渠化工程行洪时,不可忽视其对生态影响;通过恢复河道的自然水文水力条件进而重建其生态环境是有效措施。     

Spatio‐temporal habitat dynamics in a changing Danube River landscape 1812—2006

Modern, holistic concepts dealing with river/floodplain ecology recognize the key role of hydromorphological turnover processes for the development of distinct habitat patterns. Such patterns, in turn, are a vital basis for the extraordinary biodiversity of riverine systems. Natural braided/anabranched river systems in particular are characterised by high turnover rates; in the mid‐term, however, they are thought to stay in dynamic equilibrium (shifting‐mosaic steady‐state) as long as the physical framework conditions remain unchanged. This study analyses both the historical composition and the spatio‐temporal development of riverine habitats associated with an anabranched section of the Austrian Danube River. A habitat age model was used to analyse the age structure of the different habitat types. The results for the period 1812–1821 prior to channelization indicate that terrestrialization and habitat ageing were almost balanced with habitat regeneration and rejuvenation. Even though intensive morphological changes occurred, the Danube here largely persisted in dynamic equilibrium. The first channelization measures between 1821 and 1838, when 21% of the main channel banks were embanked, slightly promoted habitat regeneration. From 1859 onwards (80% embanked) until 1925, the natural habitat life time cycle was disrupted and the regenerating processes almost ceased. Altogether, human interferences led to a river landscape in a morphologically static state governed by significant terrestrialization (habitat succession) and habitat ageing. Without natural disturbances or, alternatively, targeted habitat management strategies, such an ecosystem soon lacks morphologically young habitats and adequate site conditions for a river/floodplain type‐specific biocoenosis. Copyright © 2010 John Wiley & Sons, Ltd.