超宽带雷达实验系统中大功率纳秒级脉冲源的研制

分析了超宽带雷达试验系统对脉冲源信号的具体指标要求,提出超宽带雷达用脉冲源的指标规范。根据具体系统指标,选择全固态微波电路方案,研制出了系列的数千伏、纳秒级、超宽带雷达用脉冲源。基于微波PCB电路结构、利用雪崩三级管雪崩效应进行设计。为减小反射,提高脉冲波形指标,提出了新颖的欠电荷充电法。文中详细讲述了电路设计、重要电路结构以及投入超宽带雷达试验系统应用,目标探测试验相关结果。     

一种有载频超宽带脉冲源设计

针对无载频脉冲低频分量大、辐射效率低、频带可调性差等问题,设计了一种以阶跃恢复二极管、D触发器及超宽带调制器为主的宽频带、高重复频率、低振铃水平的有载频超宽带脉冲源。该脉冲源电路由驱动电路、高速开关电路、整形电路、超宽带调制器及振荡器电路组成。实测结果表明,脉冲源输出脉冲信号重复频率可达125 MHz,脉冲宽度600 ps（底宽）,脉冲振铃水平低于10%,峰-峰值为5.4 V,-10 dB带宽可达4.2 GHz。脉冲信号中心频率与载频相同,可在6.6~8.5 GHz之间灵活设置。利用所设计的脉冲源进行时域测量,其结果与矢量网络分析仪频域测量结果相比幅频特性均方根误差小于0.21 dB。该脉冲源可应用于超宽带时域测量、短距离高速无线通信、高精度室内定位等应用。     

一种新型的超宽带细步进频率源设计

介绍了一种利用DDS、PLL和正交调制技术实现超宽带、细步进、低杂散频率源的设计方法。与传统混频锁相相比,采用正交调制技术具有方案简洁、电路简单、输出频带宽、体积小等优点。给出了一种基于AD8349型正交调制器的超宽带频率源设计实例,该设计已在工程中得到应用,其测试结果满足工程要求。     

一种新型的超宽带细步进频率源设计

介绍了一种利用DDS、PLL和正交调制技术实现超宽带、细步进、低杂散频率源的设计方法.与传统混频锁相相比,采用正交调制技术具有方案简洁、电路简单、输出频带宽、体积小等优点.给出了一种基于AD8349型正交调制器的超宽带频率源设计实例,该设计已在工程中得到应用,其测试结果满足工程要求.     

基于IEEE802.15.4a信道的高性能脉冲超宽带系统

随着通信技术的不断进步,超宽带技术作为一种新型无线通信方式,较传统无线通信方式具备许多技术上的优势,在许多应用领域如航空、医疗、军事以及消费类电子产品中都有着广阔的应用前景和特有的应用价值。文中在对脉冲超宽带系统的信源、信道、接收机进行理论分析的基础上,研究了一种具有高性能的脉冲超宽带系统并对该系统进行了建模和仿真。根据仿真实验结果分析得出该系统的各项性能要远远优于其他脉冲超宽带系统。     

一种超宽带捷变频源的研制

本文介绍了一种超宽带捷变频源的设计与实现过程，该频率源采用直接模拟合成方式，通过合理的频率划分和高性能的开关滤波组件技术实现了超宽带、捷变频、低相噪、低杂散的优异性能，并给出了最终测试结果。实测结果表明该频率源在 Ku 波段 6GHz 带宽范围内具有杂散抑制优于-70dBc，相位噪声优于-103dBc/Hz@1kHz，跳频时间小于 200ns 等的性能。     

基于空时聚焦传输的多源单中继超宽带网络传输性能分析

超宽带空时聚焦传输降低了多用户传输时的互相干扰,可以让多个源节点和多个目的节点通过一个中继节点进行通信。研究了基于空时聚焦传输的多源单中继超宽带网络的传输性能,分别推导了多址阶段和广播阶段的中断概率,得到了网络吞吐量与用户数目、节点距离、超宽带脉冲宽度、信号帧周期、接收信干噪比等参数之间的解析关系,并通过最大化网络吞吐量以及优化结果分析得到了传输方案的设计准则。最后,仿真结果验证了不同路径损耗因子下2个阶段的中断概率。     

一种低成本简化结构的超宽带光纤光源

报道了一种新型的低成本、简化结构的超宽带光纤光源.不同于常规的超宽带光纤光源,该结构只用了一个980 nm半导体激光器作为抽运源.通过调整抽运功率和掺铒光纤长度,得到了80 nm带宽的C L波段的宽带光输出.     

基于定位的超宽带传感器网络路由算法研究

超宽带定位技术应用于移动传感器网络路由算法是目前研究热点,该文提出一种基于超宽带定位的源动态路由算法,通过超宽带定位建立网络拓扑,并根据节点移动速度来反映节点的移动效应;通过受限泛洪和移动预测两种路由机制来提高路由性能.仿真结果表明,该算法能提高移动节点的路由成功率,降低路由平均延时.     

超宽带射频识别源脉冲设计与辐射掩蔽分析

超宽带射频识别(UWB-RFID)的调制信号需满足规定的频谱辐射掩蔽,介绍超宽带射频识别的基本原理,分析跳时脉冲位调制(TH-PPM)的原理;研究源脉冲高斯波形的能量谱密度特性,提出一种线性组合迭代算法,由该算法合成源脉冲,验证该脉冲合成算法是可行的。     

Multiple ultra-wideband signal sources exploiting XPM in SFRL

A novel scheme for all-optical broadcast ultra-wideband (UWB) monocycle pulses generation based on cross-phase modulation (XPM) in semiconductor fiber ring laser (SFRL) is proposed, in which three UWB positive or negative monocycle pulses can be generated simultaneously. A comprehensive broad-band dynamic model for this kind of all-optical broadcast UWB monocycle sources is established, which is further applied to numerically analyze the impacts of injection current of semiconductor optical amplifier (SOA), the power and wavelength of the signal light on the performance of the UWB positive monocycle pulses with higher power spectral density. The results show that the spectra of the UWB positive and negative monocycle pulses generated by this scheme match the Federal Communications Commission (FCC) definition quite well. Three UWB positive monocycle pulses with better performance can be obtained when the power of signal light is at a high level, and three other UWB positive monocycle pulses with good tolerance to both the injection current of the SOA and the wavelength of the signal light can be obtained. In addition, the powers of the lasing light coupled into the SFRL should not be strong to obtain three UWB positive monocycle pulses with better performance.     

基于聚焦矩阵的超宽带信号DOA估计

超宽带(UWB-Ultra Wide Bandwidth)通信技术是无线通信中的一个非常有发展前途的技术.基于频域模型的UWB到达角估计方法只能解决非相干源问题,因此提出了一种改进的估计方法.该方法通过构造聚焦矩阵来估计相干源问题.仿真结果表明,该方法有效易行.     

DS‐PAM UWB System Using Non‐linear Chirp Waveform

We propose a direct‐sequence pulse‐amplitude modulation (DS‐PAM) ultra‐wideband (UWB) system which employs a non‐linear chirp waveform instead of the conventional Gaussian monocycle in this paper. In the approved frequency for UWB, there exist myriad narrowband interferers. Specifically, we focus on the mutual interference between UWB systems and 802.11a WLAN. This paper offers a method to suppress this inband narrowband interference by introducing a kind of non‐linear chirp waveform. Using the proposed non‐linear chirp waveform, the effects of one or more narrowband interference sources with different frequencies can be suppressed. System performance of UWB systems in the narrowband interference environment can be improved. Computer simulations with additive white Gaussian noise successfully demonstrate an increase in performance with the proposed system as compared to traditional linear chirp systems.     

基于正向建模的目标超宽带电磁脉冲雷达回波仿真

为了快速获取超宽带（ultra-wideband,UWB）电磁脉冲激励下雷达目标的时域电磁响应,提出了一种基于散射中心正向建模的目标时域回波仿真方法.从目标几何模型出发,利用空间射线分集技术对强散射源进行分离,通过模型参数正向确定方法构建出目标的属性散射中心模型,用以表征目标高频电磁散射特性,并在UWB电磁脉冲激励下进行仿真运算,获得目标时域回波信号.以典型目标SLICY为例,基于正向建模的散射中心模型,快速获取不同UWB电磁脉冲激励下的雷达回波信号,与高频仿真方法得到的一维距离像（high resolution radar profile,HRRP）进行对比分析,吻合良好.由此验证了本文提出的回波仿真方法的有效性,为不同辐射源激励下目标的快速电磁响应研究提供了一种新思路.     

基于功率合成的超宽带冲击雷达研究

用电路合成和空间合成技术，将多个数干伏、纳秒级、超宽带脉冲源合成为兆瓦级高功率脉冲源；文中设计了一套由功率合成的全固态脉冲发射机、超宽带平面喇叭收发天线阵、正交解调采样接收机、主控计算机四大部分组成的冲击体制雷达目标探测系统，介绍了系统的工作原理；给出了实际系统目标探测的外场试验相关试验结果，验证了系统的可行性以及信号处理算法的正确性和有效性，为高功率冲击体制雷达技术的发展奠定了一定的实践基础。     

Self-sustained UWB Sensing: A Link and Energy Adaptive Approach

Energy efficiency is a challenging issue in autonomous and distributed sensing systems, especially when these systems are powered by renewable energy sources. In this paper, we present a link and energy adaptive UWB-based sensing technique to improve the detection time coverage and detection range coverage for self-sustained embedded applications. The basic idea is derived from the fact that domain-specific information in such applications is often available. Thus, by jointly exploiting the link information between the transmitter and receiver of the UWB pulse radar, and the non-deterministic characteristics of the renewable energy, the proposed technique dynamically adjusts the pulse repetition frequency of the UWB radar to enhance the sustainable operation under the unreliable energy supply. The overhead of the proposed technique is negligible as compared with the overall energy consumption of the UWB pulse radar. It was demonstrated that the proposed technique can achieve much better detection time coverage and detection range coverage than the conventional UWB radar. The proposed technique is also insensitive to many practical issues such as the limited battery capacity.     

Application of underdetermined blind source separation in ultra-wideband communication signals

Aiming to the estimation of source numbers, mixing matrix and separation of mixing signals under underdetermined case, the article puts forward a method of underdetermined blind source separation （UBSS） with an application in ultra-wideband （UWB） communication signals. The method is based on the sparse characteristic of UWB communication signals in the time domain. Firstly, finding the single source area by calculating the ratio of observed sampling points. Then an algorithm called hough-windowed method was introduced to estimate the number of sources and mixing matrix. Finally the separation of mixing signals using a method based on amended subspace projection. The simulation results indicate that the proposed method can separate UWB communication signals successfully, estimate the mixing matrix with higher accuracy and separate the mixing signals with higher gain compared with other conventional algorithms. At the same time, the method reflects the higher stability and the better noise immunity.     

新型超宽带脉冲源

研制出ＧａＡｓ：Ｃｒ，Ｆｅｐ：Ｆｅ光导开关，利用光导开关产生高功率皮秒脉冲，实验显示了所产生的皮秒脉冲波形，此种新型超宽带脉冲为研制超宽带雷达提供新型的脉冲源。     

UWB passive microwave imagery from static discharge effects

It is well known that spark transmitters can be sources of ultra-wideband (UWB) radiation. It is also known that high-voltage low energy static discharges are ubiquitous in nature, whenever there is friction between surfaces. Provided is a simple electromagnetic model and it is suggested that it is feasible to construct an ultra-wideband correlator capable of imaging a region of space containing such sources. This would permit a new window of observation on several physical processes, with applications ranging from observations of ice flows to covert operations.