基于蓝牙无线模块的篮球计时计分器设计

本文提出了基于蓝牙无线模块的篮球计时计分器的设计方案,使用89系列的单片机以及c语言程序完成了相关的设计。采用计数的方式实现了分数的累加以及时间的倒计。采用蓝牙无线模块的设计使其使用更便捷,便于进行推广运用。     

突发OFDM系统中同步算法的FPGA实现

根据突发OFDM系统的特点,提出了一种具有实用价值的同步实现方法。具体分析了突发OFDM系统中利用PN序列联合实现符号定时同步和小数频偏同步的算法,并阐述基于FPGA的实现过程。由Verilog HDL语言描述的同步模块由复数乘法模块,求和累加模块,比较判断模块和CORDIC模块等构成。系统采用Xilinx ISE 10.1来完成开发,同时给出了其在ModelSim SE 6.2b下的仿真结果,结果表明该方案是完全可行的。     

一种基于相干累加的并行伪码快速捕获算法

介绍了一种适于高动态、低信噪比环境下的伪码快速捕获算法。分析了相同累加点数下,相干累加和非相干累加各自的优缺点,并在此基础上对扩频增益和扫频点数量方面进行优化,进而提出一种基于时域PN码相关的分级捕获并行处理的方法。仿真结果和分析表明,该方案能在高动态环境下实现信号的快速捕获。     

一种低复杂度直扩信号伪码捕获增强方法

基于串行累加抵消结构,提出了一种简单的多符号相干累加方案。该方案可用于直扩通信系统接收机中,以提高相关峰的检测信噪比和伪码捕获概率。分析了多符号相干累加器增强直扩信号伪码捕获性能的基本原理,讨论了所提方案的设计思路和实现问题。计算机仿真和FPGA实现证明,与经典的并行分级相加累加器相比,所提方案在不降低伪码捕获性能的基础上,具有非常低的硬件复杂度,且输出时延较小。     

BP神经网络图像压缩算法乘累加单元的FPGA设计

提出一种基于三层前馈BP神经网络实现图像压缩算法的方案,该方案采用可重载IP核和VHDL代码相结合的设计方式.对方案中重要单元一束累加单元进行了FPGA设计,该模块设计采用流水线处理方式,增大了数据吞吐量,减小了系统延时,提高了时钟频率,并完成了该单元的行为级功能仿真.仿真结果验证了FPGA设计的可行性.     

基于动态规划方法的能量累加算法的FPGA实现

给出一种基于动态规划的能量累加算法的FPGA实现方案，对其中求最大值模块的实现结构及对外部存储器的控制部分做了详细的分析及优化，提高了算法实现的速度，解决了算法运算量大与实时性之间的矛盾。     

一种快速雷达信号脉内调制识别分析方法

针对类信号的脉内调制识别问题,提出了一种基于短时傅里叶变换(STFT)和瞬时累加自相关的快速雷达信号脉内调制识别方法。采用由粗到细的识别方案,依据累加STFT频谱带宽将信号分为调频和调相信号。采用时域累加瞬时自相关识别BPSK和QPSK信号,利用STFT频谱的时域特征识别LFM和NLFM信号,经仿真实验分析,在较低信噪比下可正确实现信号识别,该方法适于FPGA的快速实现。     

低信噪比环境下短扩频码捕获性能的改善

介绍了低信噪比环境下基于FFT的扩频码捕获技术,提出了在相同累加段数情况下提高性能的方案。作为提高相干增益的两种方式,相干累加和非相干累加各有优缺点,在一定的数据长度内合理地设计累加方式对提高捕获性能大有帮助。基于两种累加方式的性能介绍了一种两路非相干积分的累加方式。对于GPS信号,在低信噪比的环境下的仿真证明,在一定长度下优化后的累加方式相比非相干累加和普通混合累加方式能够得到更好的捕获效果(更高的检测概率)。     

激光雷达测风系统信号采集处理研究

为满足风场对风速测量的需求,研制了基于FPGA的激光雷达测风系统高速信号采集处理模块,负责对激光雷达回波信号采集、快速傅里叶变换(FFT)及频谱数据累加平均运算.将采集到的1024点回波数据通过流模式、块浮点结构FFT运算,分别得到单次频谱数据和1024次累加平均频谱数据,并利用数据传输模块可靠传输至上位机进行显示与分析.通过搭建工作波长为1550 nm的连续相干激光雷达测风系统,对信号采集处理模块进行指标测试和累加平均滤波算法验证.测试结果表明:该采集处理模块能够在100 MHz时钟下对回波信号实时采集处理,频谱分辨率达到97.66 kHz,将风速测量精度提升至7.57cm/s.     

基于单向累加器的无向可传递闭包图认证

提出了使用单向累加器进行无向可传递闭包图认证的新方法,构造了具体认证方案.签名时,签名者对节点集合的等价类进行累加,并为节点签发包含部分累加值的证书.累加值构成了图的签名,证书表明了节点对等价类的所属关系.验证时,只需对相关节点的证书做一次累加运算,便可验证节点间边的存在性.通过与典型的可传递签名方案的比较,表明新方案所需的空间复杂度和时间复杂度更小.另外,新方案同时支持节点和边的动态增删,这解决了Micali和Rivest提出的一个公开问题.     

A token circulation scheme for code assignment and cooperative transmission scheduling in CDMA-based UAV ad hoc networks

Code division multiple access (CDMA) ad hoc networks have been considered a promising multiple-channel networking architecture for connecting tactical platforms in battle fields. In this paper we consider a network of a swarm of unmanned aerial vehicles (UAVs) that are used in a tactical surveillance mission. The UAVs are assumed to have multiuser detection capability and form a CDMA-based ad hoc network. A token circulation scheme is proposed to conduct functions required at the medium access control layer including detection of hidden/lost neighbors, code assignment and schedule-based cooperative transmission scheduling. In the proposed scheme, a token continuously circulates around the network based on the “receive-forward” module. Through circulation of the token, each UAV can detect its hidden and/or lost neighbors in near real-time, assign codes enabling the spatial reuse of code channels without incurring code collision, and schedule data transmissions in a cooperative and distributed manner. In addition, the proposed scheme is able to take advantage of multiuser detection functionality and allows for simultaneous transmissions from multiple transmitters to a same receiver. The performance of the proposed token circulation scheme is evaluated, both analytically and through simulations. It is shown that the latency of the token is at most linearly proportional to the network size, and the average delay of a data packet increases with either the packet generation rate or the network size. The results also show that the proposed token circulation scheme is suitable for large-scale CDMA-based UAV ad hoc networks with even heavy network traffic load.     

SLM‐based PAPR reduction method using partial data circulation and side information insertion in OFDM systems

In this paper, two selected mapping (SLM)‐based schemes are proposed to reduce the peak‐to‐average power ratio (PAPR) in the orthogonal frequency division multiplexing (OFDM) systems. One is SLM‐based partial data circulation (PDC) scheme. The other is SLM‐based PDC with hamming coded side information (SI) scheme. In the PDC scheme, the partial samples within the data sequence are scrambled by circularly shifting to obtain a set of candidate sequences and, then, each sequence is combined with the corresponding SI to form the candidate OFDM symbol. With the selection of the candidate OFDM symbols with the lowest PAPR, the PAPR of the transmitted signal could be greatly reduced. In the other scheme, hamming code is used to protect the SI to improve the system performance. Simulation results show that the proposed method could reduce PAPR and it has a better bandwidth efficiency and less modules of inverse fast Fourier transform than that with the SLM‐based dummy sequence insertion scheme. Copyright © 2008 John Wiley & Sons, Ltd.     

多用户直扩超宽带信号的码片宽度估计

针对低信噪比多用户直扩超宽带(DS-UWB)信号码片宽度估计的问题,提出了利用循环谱的谱冗余估计该信号码片宽度的方法。首先推导了单用户DS-UWB信号的循环谱密度函数,进一步利用循环谱的叠加特性推导出了多用户DS-UWB信号的循环谱密度函数,最后得出了利用信号循环谱的谱冗余特性估计其码片宽度的方法。计算机仿真实验表明:多用户DS-UWB信号具有循环平稳性,其码片宽度参数可以在低信噪比时完全准确地估计出来,并且优于分段相关累积法的估计性能。     

Dynamic lightpath establishment considering four-wave mixing in multifiber WDM networks

This paper proposes a dynamic lightpath establishment scheme considering four-wave mixing (FWM) in multifiber wavelength-division multiplexed (WDM) all-optical networks. The FWM is one of the most important physical impairments to be resolved in WDM networks because the FWM induces nonlinear inter-channel crosstalk and decays the performance of WDM networks. In WDM networks, data are transmitted via lightpaths. When the effect of FWM crosstalk is large, it is highly possible that data transmission fails even if lightpaths are correctly established. The proposed scheme aims to avoid not only the blocking of lightpath establishment but also the accumulation of FWM crosstalk by means of ingenious selection of routes, wavelengths, and fibers for lightpath establishment. In the proposed scheme, a route and a wavelength are selected for each lightpath based on wavelength availability and wavelength placement of established lightpaths. Furthermore, fibers on the route are selected based on estimated FWM power. In this paper, we show the effectiveness of the proposed scheme through simulation experiments.     

基于北斗系统的伪码捕获技术的研究

北斗卫星导航定位系统是我国自主研发的有源三维卫星定位与通信系统.北斗卫星信号的捕获是北斗用户接收机的关键技术之一,捕获性能的优劣直接影响着北斗导航系统的精度和实时性要求.本文基于北斗系统,在FFT并行捕获算法的基础上研究分析了一种相位补偿和同步块累加的伪码捕获算法,并对该算法的性能进行了分析.理论分析和仿真结果表明,该方案能够大大提高信噪比,提高信号的捕获效率.     

视频轮播改造在视频会议系统中的应用

为实现视频会议智能化管理的目的,采用了视频轮播改造技术。以两处试点改造项目为例,详细介绍了视频轮播改造技术的框架结构和软件处理流程。视频轮播改造技术应用于视频会议管理中,具有易用性、通用性、创新性等特点。所开发的轮播软件已通过测试并投入现场运行。     

Zwitterionic Polysulfamide Drug Nanogels with Microwave Augmented Tumor Accumulation and On‐Demand Drug Release for Enhanced Cancer Therapy

Zwitterionic polymers demonstrate as a class of antifouling materials with long blood circulation in living subjects. Despite extensive research on their antifouling abilities, the responsive zwitterionic polymers that can change their properties by mild outside signals are poorly explored. Herein, a sulfamide‐based zwitterionic monomer is developed and used to synthesize a series of polysulfamide‐based (poly (2‐((2‐(methacryloyloxy)ethyl) dimethylammonio)acetyl) (phenylsulfonyl) amide (PMEDAPA)) nanogels as drug carriers for effective cancer therapy. PMEDAPA nanogels are proved to exhibit prolonged blood circulation without inducing the accelerated blood clearance phenomenon. Intriguingly, PMEDAPA nanogels can sensitively respond to hyperthermia by adjusting the crosslinker degree. After modified with transferrin (Tf), the nanogels (PMEDAPA‐Tf) achieve shielded tumor targeting at normothermia, while exhibiting recovered tumor targeting at hyperthermia, leading to enhanced tumor accumulation. Meanwhile, PMEDAPA‐Tf nanogels show superior penetration ability in 3D tumor spheroids and faster drug release at hyperthermia compared with that at normothermia. In combination with mild microwave heating (≈41 °C), the drug‐loaded PMEDAPA‐Tf nanogels show a pronounced tumor inhibition effect in a humanized orthotropic liver cancer model. Therefore, the study provides a novel hyperthermia‐responsive zwitterionic nanogel that can achieve augmented tumor accumulation and on‐demand drug release assisted with clinically used microwave heating for cancer therapy.     

消除荫罩式等离子体显示器动态伪轮廓方法的研究

由于目前荫罩式等离子体显示器采用ADS驱动时序,产生较明显的动态伪轮廓现象,影响图像的显示质量.本文通过分析动态伪轮廓产生原因,提出了一套通过子场发光积累取代子场发光组合来实现灰度的驱动时序方法.从仿真结果来看,该方法可以消除荫罩式等离子体显示器的动态伪轮廓现象.采用多帧图像的叠加显示和误差扩散方法,很好地解决图像灰度级不足的问题,从而提高荫罩式等离子体显示器的图像质量.     

基于索引调制OFDM雷达通信共享信号压缩感知方法研究

针对在雷达通信一体化(RadCom)系统中正交频分复用(OFDM)共享信号通信速率不高、可靠性较差的问题,该文提出一种采用子载波索引调制(IM)的OFDM共享信号方案(OFDM-IM)以及对应的基于压缩感知(CS)的雷达信号处理算法。该方案在发射端采用IM调制增强OFDM信号通信质量,在雷达接收端采用CS技术获取目标的距离-速度2维超分辨图像,进一步采用快速分段重构、2次相参积累的方法降低算法的计算复杂度。仿真实验表明,相比于传统算法,该方法能显著提升对OFDM-IM共享信号的处理性能,并实现超低距离副瓣,是一种能够同时增强雷达与通信性能的一体化共享信号方案。     

A latency-aware scheduling algorithm for all-optical packet switching networks with FDL buffers

Optical buffers implemented by fiber delay lines (FDLs) have a volatile nature due to signal loss and noise accumulation. Packets suffer from excessive recirculation through FDLs, and they may be dropped eventually in their routing paths. Because of this, packet scheduling becomes more difficult in FDL buffers than in RAM buffers, and requires additional design considerations for reducing packet loss. We propose a latency-aware scheduling scheme and an analytical model for all-optical packet switching networks with FDL buffers. The latency-aware scheduling scheme is intended to minimize the packet loss rate of the networks by ranking packets in the optimal balance between latency and residual distance. The analytical model is based on non-homogeneous Markovian analysis to study the effect of the proposed scheduling scheme on packet loss rate and average delay. Furthermore, our numerical results show how various network parameters affect the optimal balance. We demonstrate quantitatively how to achieve the proper balance between latency and residual distance so that the network performance can be improved significantly. For instance, we find that under a given latency limit and light traffic load our scheduling scheme achieves a packet loss rate 71% lower than a scheduling scheme that ranks packets simply based on latency.