A phase synchronization system of two high-speed photographic units (ВФУ-1)

A phase synchronization system of high-speed (up to 4 × 10⁴ frames/s) photographic shooting on two ВФУ-1 units used for studying a vacuum arch is described. The design alterations brought into the ВФУ-1 unit and the designed electronic control circuit allowed one to obtain one- to two-frame phase synchronization and 0.2% rate errors using comparatively simple methods.     

High-precision time synchronization of control processes in offshore oil exploration

This paper considers the problem of improving the accuracy of time synchronization of sounding acoustic signals and recording of the pulses reflected from the seabed in offshore hydrocarbon exploration. The main method of exploration is continuous seismic profiling (CSP). The method is based on the analysis of the structure of an acoustic signal reflected from geological horizons. In this case, the possibility of resolving thin-layer structures is mainly determined by the accuracy of time synchronization. An instrumental method for increasing the required accuracy is proposed. A feature of this synchronization method is the use of dynamic autocorrection to add time corrections to the main devices of CPS systems, such as navigation, source control, and record control units, after each synchronization cycle with external GPS signals. This approach differs the proposed method from the traditional one. A test model created by this method showed that the guaranteed synchronization error is in the range ± 2 µs, while the technical requirements allow for errors not less than 1000 µs.     

光电轴角编码器光电信号正交性偏差的相量校正方法

高精度光电轴角编码器中的细分是误差的主要来源,而细分误差中莫尔条纹光电信号的正交性偏差影响最大。采用相量校正方法对正交性偏差进行校正,实现电路简单,校正效果十分明显。以正弦信号为基准信号,而将余弦信号分解为0°和90°两个正交分量,0°分量就是产生正交性误差的原因,通过补偿掉该分量,即可基本消除正交性误差。为进一步减小细分误差,通过精密调节,使余弦信号的幅值与正弦信号严格相等,将正弦及其反相信号与余弦信号分别相量相加可得到严格正交的两个新相量,从而消除正交性误差。实验结果表明,经精密相位校正后,正交性偏差从1″降低到0.1″左右。     

弱电网条件下的单相频率自适应锁相环

为消除直流偏置和谐波畸变对基于二阶广义积分器( SOGI )的单相频率自适应滤波器锁相环跟踪精度的影响,提出了一种级联结构的弱电网条件下的单相频率自适应锁相方法.分析了输入直流偏置对SOGI２ 路正交输出信号的影响,以及 SOGI 锁相环的频率跟踪特性.设计级联结构的双二阶广义积分器( DSOGI )锁相环,前级 DSOGI 消除单相电网电压采样信号中的直流偏置,生成 ２ 路正交电压信号,后级DSOGI 分离出 ２ 路正交信号中的基波正序分量,并抑制电网谐波畸变对锁相环相角与频率检测精度的影响.功率硬件在环实验装置上的实物实验验证了所提锁相方法的有效性.     

基于智能手机TDOA估计的被动声源定位方法与系统实现

被动目标监测广泛应用于国防、安全等领域。针对被动声目标监测,首次提出了基于手机平台的被动式声目标定位方法,并设计和开发了原型系统。针对手机间时钟同步对被动式信号到达时间差精度的影响,采用手机内置的麦克风和扬声器发送和接收同步声信号的方式,从而避免了节点间无线同步到声信号采集间的时间延迟不确定性。为了提高信号发送和接收时刻的估计精度,将时间戳信息调制到设定的线性调频声信号,并采用广义互相关方法来实现信号波形检测。进一步,针对被动目标声源的非合作特性,采用统计判决理论和语音活动性检测相结合的方法对观测信号进行联合检波,获得被动目标声源到达时间的高精度估计,即被动声源到手机间的到达时间差。最后,通过多部手机搭建了原型系统并设计实验,结果表明定位误差不超过10%的概率达到80%。     

面向水平定向钻的透地测深系统设计

为提高水平定向钻施工中透地测深的精度,提出一种基于磁感应的双线圈测深模型并予以实现。系统采用单天线发射、三天线接收的设计方案,以STM32F103作为主控芯片,设计甚低频信号收发模块,并将三天线接收的信号用LABVIEW和MATLAB进行处理,计算出深度,最终实现透地测深。系统的测试结果证明了该设计的正确性,并表明了所设计的透地测深系统有较高的透地测深精度。     

基于采样逼近的准同步改进算法研究

准同步算法在和离散傅里叶变换结合求取周期信号的幅值和相位时,由于被测信号频率未知或仅知道被测信号的频率变化范围,在求解傅里叶系数时只能将采样频率作为被测信号频率带入造成傅里叶系数计算产生理论近似,尤其是在求解各次谐波初相角时频偏越大,求解相位误差相应增大。本文首先基于准同步测频差原理求出被测信号的实际频率,重新选取采样点使其逼近整周期采样点数,再将计算频率代入傅立叶变换中的基函数频率,最后迭代求取傅里叶系数。计算结果表明这种基于频率代入并采样逼近的改进准同步算法可以极大地提高准同步谐波算法的准确度。     

A STUDY ON A MULTI-ORDER SEMI-DIFFERENTIAL OSCILLOGRAPHIC CHRONOPOTENTIOMETRIC INSTRUMENT

ABSTRACT

By applying a convolution technique to the processing of oscillographic chronopotentiometric signals, a new electroanalytical method, multi-order semidifferential oscillographic chronopotentiometry, is presented, and a correlative instrument has been designed. The instrument can generate alternating current with sine, triangle, and square waveforms from an internal signal source, and also can be inputted other kinds of alternating current from an outside signal source. It has the capability of potential drop compensation and electrode (normal or micro working electrode) cleanup. By using the instrument, not only dE/dt-t, Y²-t, Y³-t, Y^0.5-t, Y^1.5-t, Y^2.5-t, and Y^3.5-t signals, but also the oscillographic signals synthesized by the aforementioned signals with E-t signal can be obtained.     

Synchronization controller design of two coupling permanent magnet synchronous motors system with nonlinear constraints

In this paper, two coupling permanent magnet synchronous motors system with nonlinear constraints is studied. First of all, the mathematical model of the system is established according to the engineering practices, in which the dynamic model of motor and the nonlinear coupling effect between two motors are considered. In order to keep the two motors synchronization, a synchronization controller based on load observer is designed via cross-coupling idea and interval matrix. Moreover, speed, position and current signals of two motor all are taken as self-feedback signal as well as cross-feedback signal in the proposed controller, which is conducive to improving the dynamical performance and the synchronization performance of the system. The proposed control strategy is verified by simulation via Matlab/Simulink program. The simulation results show that the proposed control method has a better control performance, especially synchronization performance, than that of the conventional PI controller.     

A monitor of chord-averaged plasma density

A single-channel two-frequency chord-averaged density monitor for measuring the plasma density in tokamaks is described. The operating principle of the monitor is based on measuring the phase shift between two microwave signals at close frequencies transmitted through plasma along one and the same chord. At an appropriately chosen difference between these frequencies, the measured phase difference is <2π in the entire range of measured densities, thereby ensuring measurements without fringe jumps. The advantage of this method for measuring the delay time compared to the pulsed method consists in an increased sensitivity of measurements owing to the possibility of filtering signals at fairly high intermediate frequency (～0.5–1 GHz). It is additionally possible to adjust the dynamic range of density measurements by selecting (optimizing) the frequency difference. The schematic diagram and the main performance characteristics of the monitor are presented. The results from laboratory tests of the monitor and those obtained with it on the T-11M facility are presented. The range of density measurements is 0.7 × 10¹²–0.7 × 10¹⁴ cm^-3, the measurement accuracy is no worse than 1%, and the temporal resolution reaches 30 ns.     

针对 3×3 耦合器幅相非对称的光纤水听器解调方法

基于3×3耦合器法的光纤水听器解调容易受耦合器分光比非理想对称特性影响,导致水听器解调结果及测量信号不准确。为解决实际中3×3耦合器普遍存在的幅度、相位非对称引入的解调偏差问题,提出基于微分交叉相乘的干涉信号幅度和相位修正解调方法。通过对三路非对称干涉信号进行两两最小二乘椭圆拟合,得到干涉信号的实际幅度和相位参数,经去直流、归一化消除幅度不对称,并将所得包含非对称相位信息的信号两两微分交叉相乘,经三角函数变换解算信号相位及其修正系数,从而实现对光纤水听器输出信号的准确解调。仿真对比了本文方法和仅考虑幅度非对称情况的解调结果,并分析比较了两种处理方法随声信号频率、幅值变化的解调误差,前者得到接近理想信号波形的解调结果和更小的解调误差。依托消声水池开展了光纤水听器解调实验,在5～30 kHz频率范围对解调方法进行了对比验证,证明了本文解调方法的有效性和稳定性。     

基于脉冲星信号的自适应同步采样方法

基于传统GPS/北斗信号的广域同步测量技术易受到恶意网络攻击,可靠性难以得到保障。为解决这一问题,本文利用脉冲星信号周期脉冲精度高、免疫于现有网络攻击的特性,提出一种新型自适应同步采样方法:首先对射电望远镜接收到的脉冲星信号进行多相滤波、消色散和周期折叠处理,得到脉冲轮廓;然后采用最小二乘法监测本地晶体振荡器频率,动态调整定时控制间隔实现自适应同步采样。为验证算法的有效性,本文采用脉冲星J0437-4715的观测数据生成同步信号,实现电网信号的同步测量,利用递归离散傅里叶变换算法计算采样数据的相角和频率,得到相角和频率平均测量误差分别为-9.75×10~(-5)°和9.83×10~(-7) Hz,验证了所提自适应同步采样方法的有效性。     

Radiation damage to microdroplets at low temperature

The effect of low temperatures on the stability of characteristic signals during electron probe analysis of microdroplets was investigated. The kinetics of the characteristic Na, K and Cl signals from lyophilized droplets of either KCl or NaCl salts were observed for 1200 s in an electron microprobe whose specimen stage temperature was either 133 K or room temperature. Samples were irradiated with 15 keV electrons, at beam current densities ranging from 7 to 70 A m^?2. Initial count rates were lower for the same samples at 133 K than at room temperature. At 133 K all the signals measured increased at the start and then, in some cases, decreased. Increases were more pronounced for measurements made at the lowest beam current density (i.e. the lowest electron dose), and for samples with the highest mass thickness; they were also more marked for KCl than for NaCl samples. At 133 K, measurements after 10 s irradiation showed no proportionality between X-ray intensity and the concentration of the elements, and proportionality was only restored when droplets had been irradiated for some time and count rates became nearer to the values measured at room temperature. Whether or not these observations reveal the existence of a fundamental physical process or a technical failure is still unknown. In no case was characteristic signal stability improved by the use of a cold stage.     

多泵磁流体动力学角速度传感器的低频拓展设计研究

针对磁流体动力角速度传感器对低频( <1 Hz)信号检测性能差的问题,在原有的角速度传感器的基础上提出了一种 含多磁流体动力泵的角速度传感器。 采用改进传感器机械结构的方法,在流体通道边缘周向上均匀构建多个磁流体动力 泵,并优化了流体泵磁极形状,以提高流体传感环中径向流速分布大小与稳定性,增强低频下科里奥利力效应。 仿真与实验 结果表明设计的多泵结构传感器相比于单泵结构,径向流速分布提高了 20. 28% ,流体泵通道磁场均匀度增加了 38. 36% 。 测试实验中施加补偿电流后,传感器可以实现对低频角速度信号的检测,全通带范围内幅值波动误差小于 0. 5% ,相位差减 小到 0 ~ 10°范围内。     

高功率移相器的电子束封焊技术

研究了高功率移相器盒体与盖板的电子束封焊工艺技术。通过接头的结构设计解决了一次启盖返修问题;通过专用夹具的设计有效地控制了温升,经点温计测量最大温升不大于60℃;采用一条焊缝两次焊接工艺保证了焊缝的熔深要求,改善了焊缝质量,经氦质谱检漏仪测试,气密性优于1．013X10^-3Pa．cm^3／s的氦漏气率。该移相器已成功地应用于某雷达天馈系统。     

微波宽带超高精度双向时间比对技术研究

当前微波双向时间比对技术广泛应用于视距区域站间时间同步领域,能够达到纳秒站间时间同步水平,对于时间同步 指标更高的应用场景还有待进一步提升。 本文利用大带宽扩频信号和载波相位在时间测量性能方面的潜在优异性能,提出了 基于宽带信号调制解调技术的微波双向载波相位时间比对方法,设计了原型试验系统,利用氢原子钟和相位微跃计验证了实验 室条件下系统的测量不确定度(A 类)0. 27 ps 和分辨力 4 ps,达到了预期效果,为后续远距离试验和应用推广奠定了坚实的技 术和试验基础。     

Gearbox fault diagnosis using adaptive zero phase time-varying filter based on multi-scale chirplet sparse signal decomposition

When used for separating multi-component non-stationary signals, the adaptive time-varying filter(ATF) based on multi-scale chirplet sparse signal decomposition(MCSSD) generates phase shift and signal distortion. To overcome this drawback, the zero phase filter is introduced to the mentioned filter, and a fault diagnosis method for speed-changing gearbox is proposed. Firstly, the gear meshing frequency of each gearbox is estimated by chirplet path pursuit. Then, according to the estimated gear meshing frequencies, an adaptive zero phase time-varying filter(AZPTF) is designed to filter the original signal. Finally, the basis for fault diagnosis is acquired by the envelope order analysis to the filtered signal. The signal consisting of two time-varying amplitude modulation and frequency modulation(AM-FM) signals is respectively analyzed by ATF and AZPTF based on MCSSD. The simulation results show the variances between the original signals and the filtered signals yielded by AZPTF based on MCSSD are 13.67 and 41.14, which are far less than variances (323.45 and 482.86) between the original signals and the filtered signals obtained by ATF based on MCSSD. The experiment results on the vibration signals of gearboxes indicate that the vibration signals of the two speed-changing gearboxes installed on one foundation bed can be separated by AZPTF effectively. Based on the demodulation information of the vibration signal of each gearbox, the fault diagnosis can be implemented. Both simulation and experiment examples prove that the proposed filter can extract a mono-component time-varying AM-FM signal from the multi-component time-varying AM-FM signal without distortion.     

Ultra-resolution phase comparison method combining phase synchronous detection and common frequency source

With the improvement of frequency standard comparison and precise frequency and phase processing technique, the high-precision frequency measurement, phase comparison, phase locked loop and signal processing are necessary. Combining phase synchronous detection principle and common frequency source, an ultra-high resolution phase comparison method is presented in this paper. Using the concepts of the equivalent phase comparison frequency, group period phase processing, phase group synchronization and phase quantization step and so on, and the high stability of common frequency source, the resolution with picosecond or subpicosecond can be easily obtained and ±1 count error in traditional phase comparison approach can be eliminated. Experimental results show that the measuring precision better than femtosecond in one hour can be achieved in the long-term frequency standard comparison.     

低相噪大面积平衡光电探测器

为了实现对光泵原子磁力仪系统中发散的快速调制光信号的精密相位检测,解决现有平衡光电探测器存在的接光面积小、增益小、带宽小及相位性能不理想等问题,本文采用基于结点差分电流的平衡差分探测方法,分析了平衡探测器抑制系统共模噪声的机理,通过优化元件和提高带宽设计出具有低相位噪声且单管接光面尺寸达到10mm的大面积平衡光电探测器,并进一步利用双板隔离式的制作方法避免了热噪声干扰,实现了其低相位漂移的特性。实验结果表明,该探测器-3dB带宽达到1.1 MHz,信号跨阻增益达到0.91 MΩ,在175kHz调制光信号下的相位噪声峰峰值不超过0.002 3°,能够满足碱金属原子磁力仪系统光信号精密相位检测的要求。     

高精度电压气象信号产生电路设计

针对电压型气象传感器（湿度传感器HMP45D、辐射传感器TBQ-2B和气压传感器PTB220）输出信号的特点,以低功耗处理器、新型DAC、低失调电压的信号调理电路为核心,设计了一种可程控的高精度电压气象信号产生电路,模拟传感器的输出信号,为自动站采集器的故障判断和检定提供标准的气象信号源。设计上分别采用总线隔离技术、电源隔离技术和软件补偿等措施,提高了模拟信号的精度。测试表明：该电路工作稳定,输出电压精度高,误差小于10μV。