A NEW METHOD OF DOPPLER CENTROID ESTIMATION FOR SPACEBORNE SAR-AMPLITUDE CORRELATION METHOD

The linear relationship between Doppler centroid and range walking in spaceborne SAR data is analyzed, and a new method to estimate Doppler centroid is proposed, which is so called amplitude correlation method. Compared with clutter-lock method which is widely used now, the new method has much less computation burden and is able to give higher estimation accuracy for a quasi-homogeneous scene or a non-homogeneous scene. This is clearly verified by the experimental results of estimating Doppler centroid for SEASAT-A raw data.     

可编程直接序列扩频通信系统的数字化实现

本文讨论了利用ASIC芯片和CPU实现直接序列扩频系统数字化的方法,阐述了各部分电路的设计思路,给出了系统总体框图及实验系统的信号波形。     

数据异常值检测及修正方法研究

针对雷达测量数据中存在的异常值,对数据中的时间参数根据其变化规律的等差性进行异常值检测。对雷达发射功率、角度、距离参数异常问题,基于邻近去最值均值滤波原理,采用滑窗方式进行检测并修正。实验结果表明,提出的检测方法能够有效检测并修正数据中的异常跳变点且不改变正常值。     

A study of Reduced-Rank stap

This paper starts with the discussion of the principle of Reduced-Rank (RR) Space-Time Adaptive Processing (STAP). It is followed by a dedication of the upper bound performance of all eigen-based RR methods provided by Cross Spectral Method (CSM) under the condition of a given processor rank and an identical secondary sample size. A performance comparison between two RR STAP processors with prefixed structure and CSM is performed by the means of simulations. It is shown that the performance of time pre-filtering followed by jointly localized STAP structure (i.e. 3DT-SAP) is very close to the upper bound and thereby it is an effective RR approach.     

基于DF-OFDM多中继系统功率分配的梯度算法

DF-OFDM技术必将成为现代移动通信的核心技术,但是合理地进行功率分配是必须要解决的问题之一。传统的二分法,大多在精确度和计算量之间很难取舍。在移动通信系统抗信道衰落和提高信道容量方面,协作通信是一种很好的解决方案。针对改进型的多中继DF-OFDM系统,对一种降低计算量的梯度算法进行了简单的介绍与分析,并与二分法进行了比较。仿真结果表明,在功率约束的条件下,梯度法要优于二分法。     

Ob ject-Based Classification Metho d for PolSAR Images with Improved Scattering Powers and Contextual Features

This paper proposes a new object-based classification method for Polarimetric synthetic aperture radar (PolSAR) images, which considers scattering powers from an improved model-based polarimetric decomposition approach, as well as the spatial and textural features. With the decomposition, the scattering ambiguities between ori-ented buildings and vegetation are reduced. Furthermore, various contextual features are extracted from the ob ject and incorporated into the K-nearest neighbors (k-NN) based classification. To reduce the feature redundancy, a new Supervised locally linear embedding (S-LLE) dimen-sionality reduction method is introduced to map the high dimensional polarimetric signatures into the most compact low-dimensional structure for classification. Experimental results with Airborne synthetic aperture rada (AIRSAR) C-band PolSAR image demonstrate the superior perfor-mance to other methods.     

湍流大气中光强闪烁对光通信链路的影响

给出了用大气传输通信设备进行传输距离 3.4 km外场试验光强闪烁对光通信链路影响的实验结果 ,并简要分析了光强闪烁对信号检测的影响和误码原因     

基于诱偏原理的双基地雷达照射源防护研究

基于诱偏原理,采用双照射源交替照射,在保证接收站正常跟踪的同时实现对ARM的诱偏。并建立交替照射诱偏原理模型,进行仿真分析,仿真结果表明：采用交替照射的方式对ARM具有很好的诱偏效果。     

RAPID CODEBOOK SEARCH ALGORITHM FOR SAR RAW DATA COMPRESSION

This paper presents a simple but eifective algorithm to speed up the codebook search in a vector quantization scheme of SAR raw data when a minimum square error(MSE) criterion is used. A considerable reduction in the number of operations is achieved.     

高层长途电信枢纽楼几种典型结构体系技术经济比较

通过对信息产业部设计院及北京邮电设计院近几年设计完成的几种长途电信枢纽楼结构设计进行分析、研究、归纳出几种典型结构体系在不同高度、不同地震设防烈度情况下的技术性能及经济指标。指出了可供电信枢纽楼结构体系选择时参考的倾向性意见。