基于Simulink的PSWF求解算法仿真

针对现有椭圆球面波函数(PSWF)脉冲求解算法仿真效率低、直观性差等问题,从PSWF的微分方程定义出发,在Simulink环境中构建PSWF脉冲发生器,给出带通PSWF和具有陷波特性PSWF的脉冲设计方法,根据美国联邦通信委员会(FCC)频谱掩膜和抑制窄带干扰的要求分别产生PSWF脉冲,结果表明,该方法产生的脉冲能较好地满足FCC频谱掩膜要求,实现任意频点不同深度的陷波。     

基于LabVIEW的时钟脉冲式位移测量系统

基于时空坐标转换理论,提出将物理刻度虚拟化为脉冲刻度进行位移测量的方法在LabVIEW环境下实现系统的搭建和数据的处理;指出用频率可调的脉冲刻度来代替栅线刻度从而简化了系统结构,避免了精密刻线带来的技术难题和满足了不同测量系统的精度要求;20组测量值与真值精度的对比曲线表明,时钟脉冲式位移测量系统能够进行位移的测量并可以通过调节脉冲的频率来满足测试精度要求,达到设计要求。     

基于DDS技术的PLC可变频脉冲输出控制器设计

利用DDS技术设计一种基于CPLD器件,满足PLC可变频率脉冲输出要求的控制器.介绍了该控制器的工作原理、设计思路及实现方法.在CPLD器件上通过设置DDS频率合成的频率控制字,从而改变脉冲输出的频率变化.实验结果表明该设计脉冲输出频率准确性优于直接采用MCU定时器分频所得.     

一种新的UWB脉冲设计方法与性能分析

提出了一种新的超宽带脉冲的设计方法。采用不同幅度和延迟的高斯脉冲的组合来拟合抽样函数脉冲,实现了超宽带辐射掩蔽的高效逼近。该方法产生的脉冲波形具有实现简单、持续时间短、容易进行时域或频域调节等特点。在介绍设计原理的基础上,给出了设计时域波形的具体实现及波形所对应的功率谱密度图,使其满足辐射掩蔽的要求。最后,分析了TH-PPM UWB系统的传输性能,并和最佳单周期高斯波形进行了详细的比较,结果表明其误码性能远远优于最佳单周期高斯波形。     

一种可变插值比的脉冲成型数字滤波器FPGA 设计

通信卫星的频分复用机制, 对卫星通信系统的发送信号频谱成型提出了严格的要求。在宽带/ 窄带兼容的卫星通信系统中, 发射信号的频谱带宽随不同速率的通信应用而改变。提出了一种脉冲成型基带数字滤波器的设计方法, 将脉冲成型与插值滤波集成在一起, 采用时变系数多相结构,可以在较宽的范围内灵活调整发送信号的码率与占用频谱带宽, 满足了航空遥感数据实时传输系统的要求。脉冲成型滤波器设计针对FPGA 的结构进行了优化, 降低了硬件占用资源, 达到了通信系统的设计性能指标。     

一种用于测量快前沿高压脉冲的电容分压器

设计一种基于大电容量低压臂的电容分压器,用于测量快前沿脉冲.首先介绍了电容分压的原理,然后阐述了基于低压臂和高压臂的设计结构,随后采用高频电磁场计算方法对分压器高压臂、低压臂和整机模型进行了参数设计,时域仿真结果表明能够满足18 MHz测量带宽的设计要求,较好地控制低压臂寄生电感,实现高分压比和较宽频带的电容分压.最后通过分压器仿真与样机实验测量,结果表明能稳定提高测量频带,且结构简单,满足对峰值较高(100 kV以上)上升时间短(20 ns)的脉冲测量,且满足装置小型化发展方向,能够应用于高压脉冲以及其他暂态电压的测量.     

基于PSO算法的UWB发射脉冲优化研究

超宽带(UWB)通信系统通常采用高斯脉冲和Hermite脉冲作为发射脉冲,从其产生原理分析,发射脉冲不能同时满足时域和频域的共同约束条件。以高斯发射脉冲为例设计先加入去毛刺电路、高通滤波器等改进电路以实现时域优化,再在频域上用粒子群(PSO)算法对改进的发射脉冲电路的电参数进行优化,并做了注入干扰的仿真实验。实验表明:经PSO算法优化后的改进的UWB发射脉冲性能大大改善,满足UWB通信系统的各项指标要求。     

闪烁脉冲时间信息实时处理单元设计

多阈值采样法是以闪烁脉冲特征模型为先验知识,通过预设多个阈值电压,对脉冲上升沿数字化得到的时间-阈值采样点进行最小均方误差拟合以精确获取脉冲起始时间.高计数率是目前PET仪器发展的一个热点方向,这就要求采用多阈值方法提取时间信息的数据获取系统具有快速高效处理脉冲以减少系统死时间的能力.论文提出了一种基于FPGA的闪烁脉冲上升沿拟合算法,通过数据预处理技术、流水线设计结构和并行处理简化算法复杂度,实现实时闪烁脉冲时间信息快速获取.仿真和实验结果表明,在FPGA上实现该算法的处理速度和精度均达到设计要求,可以满足在高计数率环境下对闪烁脉冲进行实时处理的需求.     

基于FPGA的电磁超声脉冲信号发生器的设计

激励信号源是电磁超声检测系统的核心模块之一,其输出信号决定了电磁超声检测仪检测的质量。按照电磁超声检测系统对激励源的要求,设计了相应的正弦脉冲激励源。该设计系统主要包括FPGA的硬件语言合成脉冲信号、D/A转换、滤波放大、功率放大和阻抗匹配等硬件电路。该系统可输出频率、初始相位、占空比可调的脉冲正弦信号,满足EMAT对激励源的要求。可为设计便携式的电磁超声检测仪提供借鉴。     

连续时间线性脉冲系统的有限时间滤波

研究了连续时间线性脉冲系统的有限时间滤波问题。一方面给出了滤波误差系统有限时间稳定和满足性能要求的充分条件,并且给出了滤波器的设计方法。另一方面为了避免设计方法中出现的耦合问题,给出了另外两个结论。最后通过数值算例表明了结论的可行性和有效性。     

超宽带同轴大功率八路功分器设计

针对传统大功率多路功分器带宽窄体积大的问题，提出了利用四分之一波长阶梯阻抗变换原理，设计超宽带的多路功分器的方法。这种设计方法不仅解决了多路功分器各级之间互联线造成的带宽变窄的问题，而且还利用互联线实现了超宽带的阻抗匹配。最后采用上述方法设计了工作在0．8-6．oGHz频带内的超宽带八路功分器，获得了的驻波比小于1．4，采用同轴腔体结构，插损小于0．8dB，完全可以满足电子对抗工程中对于超宽带大功率合成的需要。     

Beamforming of UWB pulse array and its implementation

This paper firstly introduces a realistic ultra-wideband (UWB) pulse model and discusses the principle of sensor array beamforming for UWB pulse signals. Then the differences between a UWB pulse array and narrowband sinusoidal array are studied. Based on it, the problem of realizing a digital and applicable variable delay circuit (VDC) to compensate the channel propagation delay accurately for UWB pulse array beamforming is addressed. In our work, fractional sample delay compensation filters (FDCF) are combined with delay lines to build up accurate VDCs. As a result, the Lagrange interpolation method based on maximally flat criterion is found to be most suitable for the fixed beam steering; and Farrow structure is recommended to satisfy the need of rapid beam adjustment. In the simulation experiments, two kinds of directivity pattern for an UWB pulse array are studied and compared with that of sinusoidal array. The effectiveness of the presented scheme is verified by the simulation results, which show that the VDC implementation by digital lines and FDCF can remarkably improve the performance of the directivity patterns of UWB pulse array especially for the system with low sampling rate.     

Design of a Low-Noise UWB Transceiver SiP

Ultrawideband (UWB) wireless communication systems are emerging as a promising solution for high-data-rate and short-distance wireless data transmission. In this article, we introduce a low-noise UWB transceiver SiP design for a compact implementation in a small mobile platform. The SiP's transmitter chip has a fully digital circuit implementation with a passive band-pass filter to meet a US Federal Communications Commission (FCC) regulation, and the receiver chip has a noncoherent architecture. To reduce noise generation and coupling in the densely integrated design, we considered signal integrity issues in the high-frequency channel and power integrity issues on the power distribution network (PDN) in the SiP substrate. Circuit-level and full-wave simulations confirm that the proposed design methodology improves signal integrity and power integrity. The UWB transceiver SiP consists of a fully digital transmitter system and a noncoherent receiver system.     

基于UWB无线通信技术在矿井中的应用研究*

介绍了我国煤炭开采中数据通信的现状和UWB的发展,阐明了脉冲产生方法及工作原理.详细分析了UWB抗多径、低功耗、强穿透力和高集成化等特点.结合煤矿井下的实际情况,提出了超宽带是一种适合煤矿井下且具有很大发展前景的无线通信技术.比估计的自适应变速方法.该方法根据估计流星信道信噪比的变化情况,动态地改变系统的比特速率,实现自适应变速,从而有效提高了流星信道利用率,实现数据的可靠传输.仿真结果表明,在相同信道条件下,该系统的数据通过量比固定速率传输系统提高2～4 倍,是一种有效而可靠的通信方法.     

Pulse shaping method to compensate for antenna distortion in ultra-wideband communications

In the ultra-wideband (UWB) communication systems, a critical spectral mask is released to restrict the allowable interference to other wireless devices by the Federal Communications Commission (FCC), and then some pulse shaping methods have been presented to fulfil the mask. However, most pulse shaping methods do not consider the antenna distortion which cannot be neglected in the UWB communication systems compared with the conventional systems. To this end, an orthogonal wavelet based pulse shaping method is proposed in this paper to integrate compensation of antenna distortion into pulse shaping. Simulation results show that the novel pulse shaping method can be used to achieve compensation for antenna distortion, optimization of transmission power spectrum, and simplification of the algorithm, as well as simple implementation of the pulse generator.     

Complex radio frequency (RF) communications with virtual pulses

A novel complex pulse forming technique has been developed using ultra wideband (UWB) frequency concepts where multiple carriers are modulated by the pulse width of the primary signal source. Specialized modulation of the pulse train provides an effective communication medium with inherent advantages of an UWB system. The multiple frequency nature of the non-traditional “pulse” formation provides a means of implementing UWB without the necessity of complex pulse formation of the classical UWB. The particular example of the research implemented in this paper allows explicit user choice of the specific UWB frequencies, e.g., ISM frequencies, to avoid current restrictions of the Federal Communications Commission (FCC). The reported method also contains an implicit property to support secure information transmission to receivers at known distances.The objective of this technique is an easy to form communication pulse having UWB low energy advantages along with the freedom of implementation without license requirements from regulating authorities, while adhering to the set limits of intentional radiators. The method chosen in this case was based on having the sum of energies from multiple frequencies remain within the restricted radiation limits at the correlated receiver. Included in the implementation technique is the inclusion of the signal fading effect as part of the modulation technique. The relevance of this pulse forming technique is in the simplicity of spreading the transmitted power among multiple frequencies without the issue of decay factor in the current methods. The result presented gives two sets of relative amplitudes of the transmitted frequencies identifying the transmitted character, e.g., 0 or 1. A form of amplitude encryption, due to the RF signal fading effect was also presented as advantage in the technique.     

基于CPLD高速可程控数字延迟线的设计与实现

针对兰州重离子加速器冷却储存环(HIRFL-CSR)踢轨磁铁(Kicker)电源的需要,设计了一种基于可编程逻辑器件(CPLD)的高速可程控数字延迟线系统。文中分析介绍了数字延迟线系统结构、工作原理及CPLD芯片的设计并给出了仿真波形。该方案满足了Kicker电源对脉冲进行适当延迟的要求,解决了Kicker电源系统脉冲同步的问题。     

Downlink TCP performance under cross layer rate and power allocation in infrastructure TH-PPM UWB networks

Ultra wideband (UWB) systems are currently an important wireless infrastructure for efficient short-range communications and mobile applications. To improve the system efficiency while guaranteeing the radio link level quality of services, the transmission rate and power of the mobile nodes in UWB based infrastructure networks can be dynamically adjusted by executing an optimization algorithm at the access points (APs). In this paper, we present a cross layer rate and power allocation algorithm based on the multilayer model of time hopping (TH) pulse position modulation (PPM) UWB multimedia networks. We consider the performance of the TCP protocol under the proposed cross layer allocation scheme in various realistic UWB based infrastructure networking scenarios.     

超宽带无线电系统跳时技术的研究

超宽带无线电系统中最常用和最典型的信号是时域上的极窄脉冲串。为了使超宽带系统的功率谱进一步平滑,增强系统隐蔽性和保密性,超宽带无线电系统往往都要破坏窄脉冲串的周期性,使所发射的相邻窄脉冲间的时间间隔进行伪随机的跳变。文章对超宽带基本理论、窄脉冲串时间间隔跳变的相关原理进行了介绍,提出了具体实现方法,给出了对实验样机的测试结果。