基于FPGA的二维PSD信号处理系统设计

为实现对入射光斑位置坐标的精确测量,设计以FPGA为核心的二维PSD信号处理系统。针对窄脉冲激光照射下前置放大放电路,建立相应等效噪声模型,引入频率对电路输出电压噪声的影响得到提高电路分辨率措施。搭建自动增益控制电路,并结合FPGA给出的相应增益控制策略实现对幅值大动态范围变化的光电流合理放大。设计峰值脉冲检测电路实现窄脉冲信号峰值的准确测量,其测量误差小于3%。通过FPGA设计状态机实现A/D芯片模式配置和数据读取,并搭建相应坐标解算模块和串口模块,实现入射光斑坐标的解算与传输。实验表明该系统测量非线性度小于10μm,测量精度高。     

基于单片机的窄脉冲测试仪的研制

在对多种机载设备输出的窄脉冲信号研究的基础上,给出信号的定义、脉冲的编码格式,测试需求,完成了基于单片机的窄脉冲测试仪的设计与制作,测试仪以单片机系统为电路核心,采用可编程逻辑器件,实现设备输出信号的转换、寄存、测试,阐述测试仪的硬电路、工作原则、软件流程。     

GaAs霍尔开关集成电路的研制

成功地设计并制造出GaAsMESFET霍尔开关集成电路。该电路采用了方形霍尔元件，绝对灵敏度为704mV/T；信号处理电路由差分放大电路和触发电路组成，触发电路结构类似于SCFL的D触发器。结果表明，开关性能良好，工作点合理，达到设计要求。实验结果还表明，霍尔元件和放大电路可构成灵敏度很高的霍尔线性集成电路。     

一种晶闸管移相触发电路

在闪光对焊中,焊接电流和焊接电压波动较大,因此保持电源的稳定性将直接影响焊接质量。本文介绍了一种晶闸管移相触发电路,其包括同步电路、移相控制电路、脉冲触发电路、脉冲输出电路。同步电路通过锁相环(CD4046)电路来实现的,可以准确"跟踪"网压的相位和频率,实现了触发脉冲与电源信号的完全同步,提高了晶闸管控制的精确性。此种晶闸管移相触发电路具有性能稳定,抗干扰能力强,适用于大功率电源的稳压调压。     

一种矩形脉冲信号沿控制电路设计

随着矩形脉冲信号的广泛应用,作为脉冲质量的重要参数,脉冲信号上升/下降时间越来越受到重视。针对矩形脉冲信号沿可控的要求,提出了一种对矩形脉冲信号上升/下降沿时间精密控制的电路设计。该电路基于电桥平衡原理和电容的电荷存储特性设计,利用电桥平衡原理设计高速开关,通过高速开关控制精密可控恒流产生源和恒流吸收源对电容的充/放电电流,实现对矩形脉冲信号上升/下降时间的控制。实验证明,该设计能够实现矩形脉冲信号上升沿/下降沿时间在800ps至1μs范围内可控调整。     

单片机控制的室内照明节能系统设计和实现

本文以单片机AT89C52为控制核心,设计和实现了一个室内照明节能控制装置。系统采用传感技术探测光亮度和人体的存在,用单片机控制室内照明。AT89C52单片机作为该系统控制装置的智能部件,感知人体的存在则是用到了热释电红外传感器,以光敏元件为主要元件的电路用来检测光照强度。单片机根据取样电路采集到的光照强度、人体信号、时钟电路、时间等信息,控制照明电路的开关操作,从而实现照明节能控制。     

基于FPGA的实时脉冲参数检测系统的设计

提出了一种基于可编程逻辑硬件结构的实时脉冲参数检测系统的方案,该方案对高速脉冲信号的采样序列建立微分门限算法,并以可编程逻辑硬件方式实现实时高效地获取脉冲特征参数。文中以大规模可编程器件为设计基础,以硬件描述语言为设计工具,详细地阐述了各功能模块的设计思路和具体实现方法,并进行了时效分析和功能仿真,为实时脉冲参数检测提供了一个简单有效的操作方案。     

一种时域矢量网络分析仪系统设计

针对微波网络在日益复杂的激励状态下瞬态特性的测试需求,本文提出一种时域矢量网络分析仪系统设计,主要由脉冲源模块、超宽带定向耦合器模块和超宽带采样接收模块组成.本文提出一种60 ps量级边沿的超宽带窄脉冲电路,产生系统激励.采用空气介质的厚带渐变耦合带状线方案,实现超宽带定向耦合器设计,分离入射信号和反射信号.利用跟踪保持模块和两级延迟线结构,实现10 ps步进间隔的超宽带采样接收模块设计,无失真采样超宽带窄脉冲信号.在系统测试中,实现了S参数测量、时域瞬态特性测量和故障诊断与定位功能.     

低压控制电器在干粉装置电机控制中的应用

低压控制电器是一种能根据外界的信号和要求,手动或自动地接通、断开电路,以实现对电路或非电对象的切换、控制、保护、检测、变换和调节的元件或设备,简述低压控制电器在丙烯腈、干粉生产中实现电机控制所起的重要作用。     

电磁阀电流曲线测试电路的设计

为解决机械开关启闭瞬间存在的抖动干扰问题,设计了基于光耦和MOS管的电磁阀电流曲线测试电路,编写了Labview控制软件,对电磁阀电流曲线和开关时间进行了测试,并与机械开关控制方案进行了对比。测试结果表明,采用的光耦+MOS管方案,解决了机械开关方案存在的开关瞬间抖动问题,达到了预期效果,电路结构简单、可行、有效,具有一定的推广价值;编写的软件控制信号发生器输出方波信号,对电磁阀的开启和关闭进行触发控制,使信号触发更加灵活;在该方案基础上,采用可编程程控电源、信号发生器和数字示波器,可以搭建电磁阀电流曲线自动化测试系统。     

带有余弦函数的三维混沌弱信号检测系统及电路实现

从理论上分析了二维Duffing弱信号检测系统变量输出在混沌和周期态之间交替转换。发现一种新的三维混沌弱信号检测系统生成规则,以生成4种检测系统之一的三维Liu-cos混沌系统为例,采用傅里叶变换等方法从理论上验证了新生成的三维混沌弱信号检测系统输出信号具有广域收敛性,解决了二维Duffing混沌弱信号检测系统不能广域检测和输出信号不收敛问题;新设计的三维Liu-cos混沌弱信号检测电路空中声波实验显示可抗低频声波干扰,检测性能优于二维Duffing混沌电路和新设计的Duffing＋滤波器电路,水中实验显示三维Liu-cos混沌弱信号检测电路可抗高频水声干扰,可检测波形畸变的水声信号。     

Switching Energy of Ferromagnetic Logic Bits

Power dissipation in switching devices is believed to be the single most important roadblock to the continued downscaling of electronic circuits. There is a lot of experimental effort at this time to implement switching circuits based on magnets and it is important to establish power requirements for such circuits and their dependence on various parameters. This paper analyzes switching energy that is dissipated in the switching process of single-domain ferromagnets used as cascadable logic bits. We obtain generic results that can be used for comparison with alternative technologies or guide the design of magnet-based switching circuits. Two central results are established. One is that the switching energy drops significantly if the ramp time of an external pulse exceeds a critical time. This drop occurs more rapidly than what is normally expected of adiabatic switching for a capacitor. The other result is that under the switching scheme that allows for logic operations, the switching energy can be described by a single equation in both fast and slow limits. Furthermore, these generic results are used to discuss the practical consideration such as dissipation versus speed, increasing the switching speed and scaling. It is further explained that nanomagnets can have scaling laws similar to CMOS technology.     

量子保密通信用单光子探测系统的设计初探

设计了以1310nm激光波长作为光源的单光子探测装置系统,对铟镓砷雪崩光电二极管(InGaAs-APD)作为量子保密通信单光子探测器件时的偏压生成、低温控制以及单光子信号检测进行了综合考虑,用脉冲发生器的单稳态电路等效地实现了直流电平叠加脉冲的“光子门”,用跨阻式前置放大器和精密的比较甄别器来改善系统的探测灵敏度。初期探测实验表明,能观察到-93dBm光信号的波形。     

无载波探地雷达高速取样头的研究

本文根据我们研究所开发的探地雷达系统要求,从理论上分析了取样噪声的来源、降低取样噪声的方法及途径,并设计了发射天线所需要的高速脉冲源(脉宽为纳秒数量级、幅度从十几代到300V的双极性对称高速脉冲)和从接收天线获取地下目标反射的毫伏数量级微弱信号的高速取样头以及收发双工开关。实验证明我们研制的取样头性能良好,它可以用在无载波探地雷达系统中作为信号采集器。     

应答器发射与控制电路的设计与实现

应答器通常在水下测量、定位与导航等领域发挥着不可或缺的作用,针对某项目对水下测量用应答器在长效性、实时控制等方面的需求,设计了应答器的发射与控制电路。发射电路采用集成音频功率放大器TAS5412作为主体电路,并结合换能器的阻抗特性以及调谐匹配方法,实现宽带高效匹配;通过单片机以及I2C总线对发射机的工作状态进行控制。该应答器既可根据遥控指令与参数,选择预存信号波形进行应答,也可以实时计算应答的信号波形,使用灵活方便,应答声源级可控。湖上和海上试验的结果表明,该应答器发射与控制电路工作稳定可靠,满足长效使用的工程应用需求。     

基于分数阶功率谱熵的未知水声脉冲信号检测方法

水声侦察的核心问题是在无先验知识条件下捕获其他平台发射的脉冲信号,单频(Continuous Wave,CW)信号和调频(Frequency Modulation,FM)信号是常用的水声探测脉冲.功率谱熵算法能有效检测低信噪比的CW信号,但对FM信号性能不佳,分数阶傅里叶变换(Fractional Fourier Tr...     

Applications of bubble devices

The applications of magnetic bubbles that are currently seen as most attractive and the current status of development of such devices are considered. A major application is thought to occur in solid-state mass memories. An attractive form of organization is possible whereby relatively short access times can be achieved while using only a small number of read and write circuits. A repertory dialer memory, which has been chosen as a test vehicle, has been developed. The design and performance of the propagating circuits, the self-latching magnetic gates and the generator, which comprise the memory, are discussed. A novel area of application may be in pulse code modulation (PCM) switching networks. It is shown how a network operating as a PCM crossbar switch can be designed using bubbles. A circuit is described which can eliminate the delay associated with bubble propagation in such networks.     

Finite element modelling of closed cracks in eddy current testing

The eddy current inspection of small fatigue cracks in Ti–6AL–4V is evaluated in both a finite element model and experiments. The crack was created in a fatigue process and an eddy current measurement was carried out as the resulting crack was subjected to different levels of static load. The signal showed a strong dependency of the time between the creation of the fatigue crack and the eddy current measurement. This dependency is proposed to be related to oxides forming on the crack faces. The oxide is favourable for the detection of fatigue cracks. The narrow width of the fatigue crack is important to consider in eddy current inspection and as static loads are applied across the crack faces, electrical connections arise within the crack, which has a strong influence on the eddy current signal. Four different models of the contact behaviour were implemented within the finite element model. It is shown that the electrical connections that arise within small fatigue cracks, as well as the influence from the narrow opening as tensile loads are applied, can be predicted by a finite element model of the eddy current method.     

Practical spread spectrum pulse compression for ultrasonic tissue imaging

Spread spectrum pulse compression is a signal processing algorithm that enhances critical system performance parameters such as signal-to-noise ratio, peak power requirements, minimum detectable signal, and total dynamic range. For this research, a digital, real-time, Barker coded, bi-phase modulator was designed and constructed, as well as a simple ultrasonic test tank containing both synthetic targets and excised goat's liver. Upon reception and demodulation of the spread spectrum ultrasonic echo, cross-correlation with a sidelobe suppression filter was performed. Due to limitations such as narrow bandwidth, and very short minimum ranges, a practical ultrasonic pulse compression system must be restricted to short code lengths. For 13 bit Barker code compression, the expected increase in signal-to-noise ratio of 11 dB was realized; at the same time greater than 30 dB of instantaneous dynamic range was maintained.     

An accurate wide-band phase shifter for sinusoidal signals using anarrow pulse duty cycle network

A technique for producing a constant phase shift of sinusoidal signals independent of frequency by using a narrow pulse switching network is proposed. A phase-locked loop circuit multiplies the frequency of the input signal by an integer factor N and, with a monostable vibrator, provides narrow pulses which excite the MOSFET switches of the network. The working frequency range of the circuit extends to more than five decades and gives a maximum error that cannot exceed 360/N°