用于四频陀螺屏蔽的软磁材料分析

四频差动陀螺由于采用恒定偏频方案，较好地解决了锁区的问题，与交变偏频的单陀螺相比有一定的优势。但是由于是采用圆偏振光，增益管过纵磁场的零漂大，因此地磁及杂散磁场对四频差动陀螺的影响是相当大的，由于一般高导磁软磁材料对应力、温度很敏感，很难适应陀螺的应用环境。因此，能否设计出适用于工程环境的磁屏蔽罩对四频差动激光陀螺是至为重要的。     

基于AD8302的X波段瞬时频率测量系统设计

介绍了几种瞬时频率测量技术,为了测量某系统接收到的瞬时信号频率,给出了基于相位检测芯片AD8302配合低噪声放大器、混频器、单片机等设计制作的X波段瞬时频率测量系统.依照方案设计了实物,并对系统整体性能进行了测试,测试结果表明,该系统可以有效的测量X波段信号的频率,测频精度优于10 MHz.     

激光差动多普勒的信号处理电路设计

随着微机电系统(MEMS)技术的迅速发展,对器件运动性能检测的需求日益迫切.采用激光差动多普勒测量技术能准确可靠地对MEMS器件进行动态特性测试.本文介绍了激光差动多普勒系统的信号处理电路的设计,主要包括放大电路、相敏检波电路和滤波电路.放大电路能将40 MHz频率信号放大100倍,相敏检波电路滤除了高频信号,分离出多普勒频移信号,滤波电路进一步滤除相敏检波电路输出信号中的载波信号和高频噪声.本电路设计最终实现了从光路系统输出的高频信号中提取多普勒信号.     

基于AD598的位移传感器的误差研究

差动变压器式位移传感器是在仪器仪表中广泛采用的电磁式变换元件。本文分析了差动变压器式位移传感器的工作原理。利用线性差动变压器的专用芯片AD598作为传感器的测量电路,深入分析了差动变压器位移传感器误差的形成,误差的测量方法及精度的标定。采用专用集成电路AD598可以大大简化差动变压器变进电路的结构,并且其线性度、可靠性和温度漂移等指标都有很大的提高。实验结果表明,基于AD598的差动变压器式位移传感器具有较高的精度。     

一个快速差动数据采集系统

本文实现了一个用微处理机控制的快速差动数据采集系统。在本系统中,采用了高精度的仪用差动集成运放AD521,十位高速逐次渐近型模/数转换器AD571,先把要采集的信号与参照信号加以比较放大,然后把放大后的偏差信号以高的分解度转换成数字信号。     

激光陀螺惯性导航系统在线快速诊断技术

国内目前对于惯性导航系统的故障诊断技术的研究主要停留在理论阶段,研制了一套激光陀螺惯性导航系统在线快速诊断装置工程样机.该样机主要包括硬件和软件两部分,硬件为一个激光陀螺惯性导航系统在线快速诊断装置,软件部分实现了串口读写、数据采集、信号处理、故障诊断等功能,样机能够对激光陀螺惯导系统进行在线检测、诊断和故障判别.该装置的研制对提高激光陀螺惯导系统的使用效率、缩短维修维护周期具有重要意义.对激光陀螺惯导系统在线测试的试验结果表明该装置具有很好的故障检测性能,能够及时发现激光陀螺惯导系统存在的故障并作出预警.     

基于DSP和FPGA的导航系统硬件平台设计

导航计算机是捷联惯性导航系统中的核心部件,主要完成初始对准和导航计算,通常由高性能、高精度的计算芯片构成.基于DSP和FPGA技术,设计应用于导航系统的导航计算机,通过时序控制和程序设计,解决了DSP芯片的自举引导、芯片之间通信、脉冲信号计数和导航计算等问题.通过长航时导航实验测量,电路能够长时间稳定工作,测量的陀螺计数误差小于e-10,导航实验速度误差小于±0.5 m/s,最大的导航径向误差0.490 8 nm,在24 h内的导航精度达到0.5 nm.平台能够提供精确快速的测量和计算数据,为惯性导航系统发挥重要作用.     

真有效值直流转换器AD536A及其应用

AD536A是美国AD公司推出的一种能够将直流/交流信号快速转换成真有效值输出的集成芯片。介绍了AD536A的工作原理、连接方式及其在中储式制粉系统中球磨机内存煤量测量中的应用。     

真有效值直流转换顺AD536A及其应用

AD536A是美国AD公司推出的一种能够将直流／交流信号快速转换成真有效值输出的集成芯片.介绍了AD536A的工作原理、连接方式及其在中储式制粉系统中球磨机内存煤量测量中的应用。     

基于ARM的便携式高精度激光功率计设计

针对传统激光功率计存在测量精度低、成本高、功耗高、便携性差等问题,设计了一种基于ARM的便携式高精度激光功率测量系统。该系统采用ARM作为核心控制芯片,实现模数转换、信号采集、量程自动切换、数据处理、LCD显示屏控制、数据传输等功能。该系统采用两节5号干电池供电,体积小、携带方便,并可通过USB接口将测量结果上传至计算机。该激光功率计不仅实现了激光功率的高精度测量,而且具有成本低、功耗低、便携性强等优点,非常适合在光信息、光通信领域及其相关科学实验和教学中使用。     

用于雷电流在线监测的多层PCB微分环理论分析

PCB(Printed Circuit Board)微分环作为一种新的测量雷电流的非接触式传感器,可实现数字化布线及全自动生产,克服了传统微分环的诸多不利因素。由于单层PCB微分环测量雷电流的灵敏度不高,本文从微分环的测量原理出发,由对单层PCB微分环测量原理分析扩展到多层微分环,得到了多层PCB微分环的相关计算公式。并给出了多层PCB微分环的等效电路,以及等效电路中电容和电感的计算公式与推导过程。最后,本文通过Matlab软件仿真分析了多层PCB微分环的结构参数对其测量性能的影响。仿真结果表明多层PCB微分环的测量灵敏度与微分环的层数存在着简单的线性关系,层数越多,灵敏度越高;并且多层PCB微分环的层数越多、层间距越小、与屏蔽壳之间的距离越小,其测量带宽就越小。本文的研究成果为后续多层PCB微分环和雷电流监测系统的实物研制奠定了理论基础。     

基于CPLD的油气井陀螺测斜仪控制电路的设计

针对油气钻井中恶劣环境条件( 150℃以上高温和100 MPa以上高压)下陀螺测斜仪出现温度漂移的现实问题,设计开发了一种对温度漂移具有补偿功能的陀螺测斜仪控制电路,以便高精度获取陀螺测斜仪的敏感信号,确保仪器在油气勘探中提供准确的钻头走向方位信息。基于CPLD的温度补偿控制电路,主要由校正网络信号预处理电路、A/D采样芯片及CPLD芯片组成。性能测试结果表明,设计的对温度漂移能够进行补偿的控制电路,具有温漂补偿能力强、测量精度高、工作稳定性好等特点,可用于油气钻井中高温高压恶劣环境条件下钻头走向方位信息的测量工作,具有一定的工程应用参考价值。     

基于时间放大技术的时间数字转换器的设计

本文基于时间放大技术设计了一种两步式的时间数字转换器(TDC),可应用于高精度的飞行测量领域。本设计采用SMIC 55 nm CMOS工艺,采用环形延时TDC作为粗量化电路,采用游标式TDC作为细量化电路。游标式TDC的精度受到延时失配限制,导致在设计时难以突破更高精度的要求。时间放大器通过放大粗量化产生的时间余量,并继续进行第二次细量化,降低了细量化电路的设计难度。针对传统时间放大器输入范围有限以及放大精确度不足的弊端,提出一种新的时间放大器结构,具有精确放大宽范围输入时间间隔的能力。仿真结果表明,采用该种时间放大器的TDC可实现的分辨率为3.7 ps,测量范围为80 ns,微分非线性(DNL)为0.73 LSB,积分非线性(INL)为0.95 LSB,该设计能够在高线性度下更好地兼顾TDC的分辨率与测量范围。     

基于精细积分法的电力系统自励磁仿真

精细积分法是一类高精度求解微分方程的方法,它摒弃了传统求解动力学方程常用的差分格式。为此,给出了同步电机的自励磁数学模型,并结合精细积分法的思想,推导出一种形式简洁、仿真快速的精细自励磁积分格式,同时考虑了发电机磁路的饱和特性。通过对自励磁暂态过程仿真发现：与隐式梯形法相比,精细积分法不仅具有非常高的计算精度和良好的数值稳定性,而且在仿真过程中可以采用较大的步长,进而提高系统的仿真速度。     

High efficiency widely tunable SGDBR lasers for improved direct modulation performance

We report on two novel approaches to improve the differential quantum efficiency (DQE) of widely tunable 1.55-/spl mu/m lasers: the bipolar cascade sampled grating distributed Bragg reflector (BC-SGDBR) laser and the gain-levered SGDBR (GL-SGDBR) laser. Each is fabricated on a robust InGaAsP/InP photonic integrated circuit platform. The lasers demonstrate improved direct modulation performance over conventional SGDBR lasers. The BC-SGDBR laser was also monolithically integrated with a semiconductor optical amplifier and photodetector receiver in order to perform wavelength conversion. Error free wavelength conversion at 2.5 Gb/s and improvements in conversion efficiency are demonstrated.     

A Practical Pll-Based Drive Circuit with Ultra-Low-Noise Tia for Mems Gyroscope

A novel phase-locked loop (PLL) -based closed-loop driving circuit with ultra-low-noise trans-impedance amplifier (TIA) is proposed. The TIA is optimized to achieve ultra-low input-referred current noise. To track drive-mode resonant frequency and reduce frequency jitter of actuation voltage, a PLL-based driving technique is adopted. Implemented on printed circuit board (PCB), the proposed driving loop has successfully excited MEMS element into resonance, with a settling time of 3s. The stable frequency and amplitude of TIA output voltage are 10.14KHz and 800mVPP, respectively. With sense-channel electronics, the gyroscope exhibits a scale factor of 0.04mV/°/s and a bias instability of 57.6°/h, which demonstrates the feasibility of the proposed driving circuit.     

1.3-μm InAsP n-type modulation-doped MQW lasers grown bygas-source molecular beam epitaxy

The effect of n-type modulation doping as well as growth temperature on the threshold current density of 1.3-μm InAsP strained multiple-quantum-well (MQW) lasers grown by gas-source molecular beam epitaxy (GSMBE) was investigated for the first time. We have obtained threshold current density as low as 250 A/cm² for 1200-μm long devices. The threshold current density per well for infinite cavity length J_th/N_w∞ of 57 A/cm² was obtained for the optimum n-doping density (N_D=1×10¹⁸ cm^-3) and the optimum growth temperature (515°C for InP and 455°C for the SCH-MQW region), which is about 30% reduction as compared with that of undoped MQW lasers. A very low continuous-wave threshold current of 0.9 mA have been obtained at room temperature, which is the lowest ever reported for long-wavelength lasers using n-type modulation doping, and the lowest results grown by all kinds of MBE in the long-wavelength region. The differential gain was estimated by the measurement of relative intensity noise. No significant reduction of differential gain was observed for n-type MD-MQW lasers as compared with undoped MQW lasers. The carrier lifetime was also reduced by about 33% by using n-type MD-MQW lasers. Both reduction of the threshold current and the carrier lifetime lead to the reduction of the turn-on delay time by about 30%. The 1.3-μm InAsP strained MQW lasers using n-type modulation doping with very low power consumption and small turn-on delay is very attractive for laser array application in high-density parallel optical interconnection systems     

基于单片机的大电感参数动态测量研究

测量如电力变压器、发电机、电抗器等大电感设备的直流电阻和电感参数意义重大,是对这类设备检测和检修不可或缺的工作。提出了一种可以同时测量大电感直流电阻和电感的动态测量方法,这种可方法只需要在测量回路中串联一个已知的电感和电阻,进行两次采样便可快速得到电感直流电阻和电感值,通过单片机进行采样和计算,能方便地同时得出大电感和其电阻值,而且测量的准确性很高,有很高的实用价值。该方法在单片机的仿真软件Proteus中得到了验证。     

Wide bandwidth and high precision power supply noise detector by using dual peak detection sample and hold circuits

In this paper, we proposed a high‐performance, high‐precision power supply noise (PSN) detector by using dual peak detection sample and hold circuits with source follower. By using dual peak detection sample and hold circuits, we can avoid PSN missing detection and therefore avoid massive PSN detection error. We also added one dummy switch to cancel the charge injection effect and to improve the PSN detection accuracy. In the proposed design, we applied one PMOS type charging circuit to enhance the operation frequency of differential amplifier, which can widen both the PSN detection bandwidth and the detection range. As a result, in the proposed PSN detection circuit, the PSN detection bandwidth can be raised from 1 GHz to 2 GHz with the PSN detection error lowered to ±3%. Moreover, the PSN detection range is widened from 10%–50%VDD to 5%–65%VDD as compared with the state‐of‐the‐art design. Copyright © 2012 John Wiley & Sons, Ltd.     

0.98-μm multiple-quantum-well tunneling injection laser with98-GHz intrinsic modulation bandwidth

We demonstrate GaAs-based 0.98-μm multiple-quantum-well (MQW) tunneling injection lasers with ultrahigh-modulation bandwidths. Electrons are injected into the active region via tunneling, leading to a “cold” carrier distribution in the quantum wells (QWs). The tunneling time (2 pS) measured by time resolved differential transmission spectroscopy agrees with the capture time extracted form the electrical impedance measurement. The tunneling barrier prevents electrons from going over the active region into the opposite cladding layer. The carrier escape time in tunneling injection lasers is larger than that in conventional QW lasers. Enhanced differential gain, minimized gain compression and improved high frequency performance have been achieved. The -3-dB modulation bandwidth is 48 GHz and the maximum intrinsic modulation bandwidth is as high as 98 GHz