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排序方式: 共有82条查询结果,搜索用时 0 毫秒
1.
导航电文的生成是GLONASS卫星信号模拟器研制中的关键部分,获得正确的导航电文信息是接收机实现定位、测速以及授时等功能的前提条件。为了满足接收机测试的需要,GLO-NASS卫星信号模拟器输出信号必须调制正确的导航电文。GLONASS卫星信号模拟器由模拟器仿真软件和信号生成单元组成。主要研究GLONASS卫星信号模拟器的软件部分。在分析GLONASS卫星信号模拟器结构和导航电文结构的基础上,详细介绍了GLONASS卫星信号模拟器中导航电文的生成过程。重点对从R inex文件中读取星历参数并转化成二进制格式导航电文的程序实现进行了深入研究,利用GLONASS接收机对卫星信号模拟器输出的仿真信号进行电文解析和定位解算,试验结果可以验证卫星信号模拟器中导航电文生成的正确性。 相似文献
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To determine the velocity and acceleration of the receivers under the requirements of high accuracy applications using global navigation satellite system (GNSS), models and algorithms based on multiple reference stations were presented in this paper. As one of the key techniques, the navigation satellites’ velocities and accelerations calculation methods were analyzed, including two cases: (1) under the requirement of real time applications, the navigation satellites’ velocities and accelerations have to be calculated by using broadcast ephemeris, the analytic expressions from three types of broadcast ephemeris, including Kepler elements, modified Kepler elements and position-velocity types, were derived, (2) under the requirement of high accuracy applications, the numerical difference method was also analyzed. Furthermore, the baseline-dependant error suppression methods based on multiple reference stations were illustrated briefly. Finally, experiments which data from multiple reference stations show that the estimation precision of this method can be improved about 15–20% compared with the single reference station real-time kinematic (RTK)-derived method both in static and kinematic cases. 相似文献
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Yu Liu Xing Zou Xiaowei Niu Zhengquan Hu 《International Journal of Circuit Theory and Applications》2020,48(12):2056-2064
According to the characteristics of the chaotic oscillator in detecting weak signals, an algorithm based on Duffing chaotic oscillator array was proposed for acquisition of weak GLONASS signals. By means of GLONASS intermediate frequency and Duffing chaotic oscillator models, Lyapunov exponent is adopted to judge the critical condition of phase track and decide whether GLONASS signals exist or not by the change of the critical condition, and numeric iteration procedure is used to calculate the exponent. Finally, the performance of algorithm is simulated using GLONASS intermediate frequency data. The results indicate that acquisition algorithm can satisfy the need of object positioning in low signal-to-noise ratio environment. 相似文献
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给出了一种用于第三代移动通信系统(3G)CDMA2000基站的时钟同步方案。由一个双星接收卡接收GPS/GLONASS标准秒信号作为整个时钟同步系统的参考,分两级锁相环实现:第一级锁相环采用软件锁相,输出10MHz信号作为第二级锁相环的参考源,第二级锁相环为2个模拟锁相环,分别输出16fc和48fc(fc=1.2288MHz)。2S信号由16fc分频得到。这种设计保证了输出时钟的长期稳定性和短期稳定性,满足协议所规定的同步精度。详细介绍了数字鉴相器、2S产生电路、相差检测及控制电路的电路设计和有关仿真结果。 相似文献
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针对GPS/GLONASS组合导航中的需要,分析了GLONASS卫星的广播星历格式,简化受力模型和星历计算方法,并给出了GPS/GLONASS的数据融合模型。 相似文献
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John Cooper Peter Daly 《International Journal of Satellite Communications and Networking》1997,15(6):247-257
Increasingly, interference effects on GNSS receivers are becoming important as more safety-critical applications such as civil aviation are employing the system. The inherent interference rejection capability of the GNSS spread spectrum modulating technique is now no longer considered adequate to remove the effects of very strong jammers. These can be generated intentionally, as in jamming situations, or unintentionally by systems such as mobile satellite systems. Continuous satellite tracking through this interference is essential for high-integrity applications. This study describes a new hardware-based GNSS interference mitigation scheme which is particularly effective against CW and pulsed CW interference. Interferers with some degree of frequency or amplitude modulation can also be reduced. The core hardware can remove two CW interferers from anywhere within the GPS P code bandwidth or the GLONASS frequency spectrum and further interferers can be removed by cascading modules. Simulation and actual data are shown. Owing to the wideband nature of the signal processing, the module introduces very little additional phase distortion and thus group delay to the GLONASS band, which has been shown to be advantageous to differential GLONASS processing. © 1997 John Wiley & Sons, Ltd. 相似文献