Space Weather in the Equatorial Ionosphere

The ‘scintillations’ observed on signals received in the equatorial region from GPS satellites are due to plasma instabilities in the F region of the ionosphere, also detected as spread F. These instabilities give rise to depletions of ionisation or ‘bubbles’. The occurrence of these events and their relation to the equatorial electrojet are reviewed. Possibilities of short-term forecasting are examined with particular attention to problems encountered in modelling the equatorial electrojet. This revised version was published online in August 2006 with corrections to the Cover Date.     

基于TMS320F2812生成移相PWM的2种办法

移相 PWM波是很多开关电源常用的驱动脉冲信号。双向全桥直流变换器(Bidirectional-Full-Bridge DCDC Converter,BDC)在双重移相控制方式下时需要 4组两两互补的移相 PWM波。文章基于 TMS320F2812型 DSP(Digital Signal Processor)分析了 2种生成移相 PWM的方法。为提高双向全桥直流变换器工作的安全性和可靠性,为移相 PWM波设置死区时间。对所提出的方法进行测试后结果良好,对于双向全桥直流变换器闭环控制系统的构建具有重要意义。     

Effect of the seed perturbation amplitude on the equatorial spread F initiation during solar minimum

The contribution of gravity wave (GW) to the initiation/development of spread F during a solar minimum year was investigated through the comparison of the observed precursory parameters and characteristics of the corresponding equatorial spread F (ESF) events. The ionospheric parameters were recorded at the magnetic equatorial station Sao Luis (2.3°S, 44°W, dip latitude 2°S) during March and October 2010. These data were used to estimate the influence of the relative gravity wave amplitude and the ambient ionospheric condition on the diurnal variation of the spread F initiation. The vertical velocity drift indicated a clear control and defines the threshold for the seasonal variability of the ESF occurrence. However, it was insufficient to solely determine or predict the day to day variation of ESF occurrence. Thus, few days with contrasting ambient ionospheric condition and magnitude of GW amplitude were analysed in order to investigate the role of the different precursory factors in the observed diurnal variation of the plasma irregularity development. The density scale length and gravity wave amplitude were shown to immensely contribute to the linear instability growth rate, especially during the days with a low post-sunset rise. Thus, the experimental observations have demonstrated the strong inter-dependence between the precursory factors and they have also highlighted the probable control of the ESF morphology.     

固液动力探空火箭箭载数据采集系统设计

针对固液动力探空火箭在进行测试、飞行试验时,需要实时测量并记录推力、燃料供给速率以及吹除系统工况信息的问题,设计并工程实现了对箭载重要设备输出信号进行监控和采集记录的数据采集系统.以STM32F103RB微控制器为核心,完成了数据采集、存储、传输等电路的设计,并在Real View MDK集成开发环境下,运用C语言完成了控制、测试程序的编写.最后,通过Real View ULINKR仿真器实现了软硬件的联合测试,验证了系统的供电控制、采样频率、工况记录等功能都满足设计要求,完成了对箭载重要设备监控和采集记录的任务.只需修改微控制器内的操控程序,就可将此数据采集系统应用于不同型号的固液动力探空火箭.      

基于TMS320F2812的CAN总线接口通用电模拟器研制

基于TMS320F2812及其内置CAN总线控制器,开发了一套适合多种CAN总线接口配置要求 的通用电模拟器硬件系统,用于某型卫星地面电联试系统中敏感器电模拟器的研制,取得了 良好效果。该电模拟器硬件系统具有CAN总线接口配置灵活、数据处理能力强、应用程序开 发方便、通用性强等特点,可用于卫星地面电联试系统中的多种电模拟器开发研制。
     

石英挠性加速度计I/F转换电路软件补偿研究

为提高石英挠性加速度计电流频率转换的线性度,本文从软件补偿角度出发,针对电流频率转换的特点,利用了曲线拟合方法对试验数据进行处理,设计了硬件补偿电路,验证了软件补偿方法可以提高电流频率转换的线性度。     

低纬电离层f0F2夜间增强的模拟研究

以太阳活动低年冬季为代表,利用二维中低纬电离层理论模式模拟低纬电离层ｆ０Ｆ２夜间增强现象,探索在赤道异常驼峰纬度附近形成该现象的可能因素或物理机制,模式在给定磁子午面内解等离子体输运方程,给出电子及各离子的浓度,速度的时空分布。在所考察条件下,低纬驼峰纬度附近ｆ０Ｆ２模式值夜间出现了明显的增强特征。     

基于DSP的导弹舵机控制系统的研究

应用TMS32 0F2 4 0DSP设计了全数字无刷直流电机的新型导弹舵机伺服驱动系统 ,详细介绍了系统的组成原理、硬件设计及控制策略。试验结果表明 ,此系统具有良好的动态和静态特性。     

On the time of minimum ionization in the F2 region

Using measurements of the critical frequency of F2 region (f_oF2) the validity of the International Reference Ionosphere model to predict the time of minimum ionization is checked. Data obtained at different ionospheric stations have been considered. The CCIR and URSI options are used to model calculations. For CCIR option the results show that good predictions were obtained for about 40% of the considered cases. For the rest of the considered data, the model predicts the minimum at times earlier than that observed in the measurements. The percentages of good predictions obtained with URSI option are lower than those corresponding to CCIR one.