TDMA卫星通信系统突发同步的性能研究

突发载波捕获和同步是TDMA系统的关键技术,使用数据序列辅助判决可有效缩短该处理过程需要的时间;在低接收信噪比下使用CAZAC序列的相关处理能够获得较高的突发捕获性能;比较了CAZAC序列和"1010"序列的载波和时钟同步误差估计性能,分析了它们在低信噪比门限时对信号快速捕获能力的影响。提出了2种序列组合应用实现载波快速同步的方案,完成信号捕获和载波估计功能。     

An efficient algorithm to eliminate temporal pumping artifact in video coding with hierarchical prediction structure

At low bit-rates, hierarchical prediction structure using quantization parameter cascading strategy will introduce a new temporal distortion, i.e., the temporal pumping artifact (TPA) presenting itself as a stumbling effect which seriously affect the subjective video reconstructive quality. This paper analyzes one important key factor which greatly influence the critical perceptual of the TPA and proposes a metric for just noticeable temporal pumping artifact (JNTPA) based on spatial–temporal masking effects in human visual system (HVS). Finally, an efficient TPA eliminating algorithm in video coding based on the JNTPA has been proposed. The subsequent experiments demonstrate that the estimated JNTPA values using the proposed metric are in line with the HVS perception and comparable with JVT-P104, the proposed TPA eliminating algorithm achieves a more smooth subjective video quality and improves the observe comfort of the human eye. At the same bit-rate, better subjective video quality can be observed using the eliminating algorithm.     

视频图像捕获系统SRAM控制器的FPGA实现

介绍了视频图像捕获系统中用SRAM直接接收一帧数字图像信号的实现方案.图像数据采集频率可达13.5MHz,信号数据用FPGA芯片实现的SRAM控制器接收,然后直接存入到处理器的外部SRAM中.     

High-precision measurement of the 14O half-life using a mass-separated radioactive beam

A high-precision measurement of the ¹⁴O half-life has been performed using a mass-separated radioactive beam in combination with a germanium detector set-up. This is the first ¹⁴O half-life measurement with a contamination-free source. The final result of 70.560 ± 0.049 seconds is in agreement with the generally adopted mean value. Received: 5 April 2001 / Accepted: 6 August 2001     

数字电视发展概要

文章中主要概述了当前国外数字电视的发展现状及国际数字电视广播的传输方案。并对国内数字电视在北京、上海、深圳三地区的发展情况作了系统的介绍。     

基于H.323的视讯会议系统的发展和测试情况

简要介绍了IP网络基于H.323的视讯会议系统的发展状况、相应标准的研究进展和主要设备的测试情况,并根据国内视讯业务发展和实际测试中的情况,对视讯会议设备本身需要面对的一些问题进行了探讨。     

思考万维网的下一步：探讨个人Web的概念

本文探讨个人Ｗｅｂ（Ｐｅｒｓｏｎａｌ Ｗｅｂ,ＰＷ）的新概念。ＰＷ帮助个从浩瀚的网络信息资源中迅速、方便地拿到他确实在用的读物;ＰＷ还有助于减轻万维网（ＷＷＷ）中因用户过多产生网络带宽冲突问题。     

HDTV解码器同步系统研究

本文讨论了在HDTV信源解码器系统中视频缓冲器的管理,深人研究了HDTV解码器中的同步系统的解决方案,在我国HDTV信源解码样机中用FPGA实现取得了较满意的效果。为设计我国具有知识产权的HDTV及HDTV的ASIC设计提供了重要的参考。     

Search for Cold Dark Matter and Solar Neutrinos with GENIUS and GENIUS-TF

The new project GENIUS will cover a wide range of the parameter space of predictions of SUSY for neutralinos as cold dark matter. Further it has the potential to be a real-time detector for low-energy (pp and ⁷Be) solar neutrinos. A GENIUS Test Facility has been funded and will come into operation by early 2003.     

光电跟踪仪低对比度目标捕获能力检验方法研究

提出了一种光电跟踪仪低对比度目标捕获能力检验方法。该方法采用可调对比度无穷远目标源作为检验装置,为被检光电跟踪仪提供对比度可准确度量的光学基准目标,用于检验光电跟踪仪的针对低对比度目标的捕获能力。介绍了检验装置的原理、组成和目标对比度标定方法,对检验结果进行了分析。该检验方法综合了光学系统性能、光电接收器性能、图像处理电路和软件及信噪比等各项指标对目标对比度的影响,全面真实地反映了电视跟踪仪的跟踪性能。