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当前基于低轨卫星的导航定位方法研究成为国内外热点,其中基于低轨通信卫星的导航定位技术更是当前研究的重点方向。然而低轨通信星座较低的时空基准精度给导航定位带来了较大的挑战,针对弱时空基准约束的低轨卫星导航定位体制设计还处在研究的初级阶段。本文针对低轨通信星座的导航定位服务需求,基于LEO通信卫星的伪码测距信号与多普勒测频信号,开展精度因子(Dilution of Precision,DOP)及定位精度均方根误差(Root Mean Square Error,RMSE)分析,并对两类测量体制下的低轨通信星座导航定位服务性能进行分析论证。理论分析与仿真结果表明,在设定低轨通信卫星10 m~30 m弱时空基准误差的约束下,多普勒测频体制具有更优的导航定位精度,其周期平滑后的三维RMSE值为1.28 m,相比伪码测距体制下的三维RMSE值优化了86.8%;二维RMSE值为0.99 m,相比于伪码测距体制提升了52.9%。本文提出了一种较为可靠的低轨通信星座多普勒定位方案,为未来低轨通信卫星用于导航定位服务提供了有益参考。 相似文献
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This paper investigates the constructive use of multipath reflections of Global Positioning System (GPS) signals for navigation in urban environments. Urban navigation applications are generally characterized by a significant presence of multipath signals. In order to maintain reliable and accurate navigation capabilities, it is critical to distinguish between direct signal and multipath. At the same time, multipath reflections can be exploited as additional measurements for those cases where the number of direct path satellites is insufficient to compute the navigation solution. The paper develops a method for the identification of multipath reflections in received satellite signals: i.e., multipath is separated from direct signal and a line-of-site between the GPS receiver and a multipath reflecting object is determined. Once multipath reflections are identified, they can be used constructively for navigation. The method presented in the paper exploits an open-loop batch-processing GPS receiver, laser scanner and inertial navigation system (INS) to identify multipath reflections in received satellite signals. Experimental GPS, inertial and laser scanner data collected in real urban environments are applied to demonstrate identification of multipath reflections. 相似文献
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超密集低地球轨道卫星通信网络能弥补传统地面网络频谱资源稀缺、覆盖范围有限的不足,有潜力提供全球大规模接入的高速率服务。由于卫星的高速移动性,卫星通信对天线性能,如波束控制能力和天线增益等,也提出了更为严苛的要求。因此,对一种新型的超材料天线——可重构全息超表面(reconfigurable holographic surface,RHS)辅助卫星通信展开了研究。RHS采用全息原理对超材料单元进行电控,从而实现波束成形。基于 RHS 的硬件结构和全息工作原理,提出了一种 RHS 辅助多卫星通信方案,该方案同时考虑卫星跟踪和数据传输。同时,设计了全息波束成形优化算法以最大化和速率。仿真结果验证了所提方案的有效性并表明了相较于传统相控阵天线,RHS提供了一种成本效益更高的卫星通信支持方式。 相似文献
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Young Hoon Kwon Ji Young Yun Dan Keun Sung 《International Journal of Satellite Communications and Networking》1998,16(4):197-208
Low earth orbit (LEO) satellite communication systems perform frequent intersatellite handovers for both fixed and mobile users. This paper proposes a satellite selection scheme for new/handover call requests when two or more satellites can be seen simultaneously. Each satellite in this scheme has a non-uniform transmitter antenna gain according to its relative position inside the coverage area. The antenna gain is proportional to the residual distance in the satellite's direction of movement and it compensates for the difference in path losses between satellite links. The residual distance distribution of the selected satellite and the mean number of intersatellite handovers during a call connection are calculated and compared with the results based on conventional methods. The proposed scheme can reduce the intersatellite handover call attempt rate without increasing system load and terminal complexity. Furthermore, this scheme can be extended to reduce both intersatellite and interbeam handover call attempt rates in a multiple spot beam environment. Especially, the average number of intersatellite and interbeam handovers during a call can be significantly reduced by using a hybrid algorithm with the proposed non-uniform power transmission scheme. © 1998 John Wiley & Sons, Ltd. 相似文献
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随着 GPS、Galileo、GLONASS 和我国卫星导航系统的持续发展和广泛应用,空间可接收和利用的导航卫星越来越多、导航信号越来越越丰富,本文针对多系统多频点信号接收的特点提出了卫星导航接收设备设计方案,分析了设计方案的特点以及相关技术的发展趋势,对接收设备的研制具有一定的参考价值。 相似文献
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Russian global navigation satellite system (GLONASS) provides civilian and military users three-dimensional position determination and navigation services as same as US global positioning system. Geometric dilution of precision (GDOP) provides a simple interpretation of positioning precision. Usual method for GLONASS GDOP calculation is matrix inversion. However this process imposes a huge calculation load on receiver, especially when large number of visible satellites exists. To overcome this problem, artificial neural network is used. Different configurations and training methods are simulated on a data base obtained by a GLONASS receiver. Then navigation precision and execution times are explored and compared. Results show that recurrent neural network has 0.00024 RMS error, which is the best against other focused tools including feed forward back propagation and radial basis function neural network with usual training and with genetic algorithm adopted weights and biases. 相似文献
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In this paper we consider the possibilities of navigation of spacecrafts designed to service artificial Earth satellites on the geostationary orbit and of space debris removal in the near-Earth space using the signals of Global Navigation Satellite Systems. We have formulated the methodology for estimation of the signals availability of navigation satellites on the geostationary orbit through the utilization of almanac of GPS and GLONASS. It has been demonstrated that in the case of reception of navigation signals, which are radiated by the antenna system within the limits of main lobe of the radiation pattern (RP), the availability of satellite navigation signals on the geostationary orbit is very low even if we utilize GPS and GLONASS simultaneously. We present the simulation results of the received on the geostationary orbit navigation satellites using the signals radiated in the main lobes in the range from ±13.8 to ±23.5° for the L1 frequency, from ±13.8 to ±26° for the L2/L5 frequencies and in the side lobes in the range from ±30 to ±60° of RP of the satellite antennas. The simulation of the navigation satellites available on the geostationary orbit is given on the 24-hour time interval. Presented results are illustrated by the calculations of number of visible satellites and by the geometric factor. 相似文献
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GPS 利用卫星发射的无线电信号,通过计算卫星与 GPS 接收机之间的相对位置, 进而确定出用户接收机在地球上的位置,可以为用户接收机提供实时的定位、测速和授时等服务。 通过使用最小二乘法,对 GPS 的定位解算算法进行研究,设计了一种基于最小二乘法的 GPS 定位解算算法。通过使用模拟源对所设计的 GPS 定位算法进行了定位解算试验验证,将定位解算结果与设定的模拟接收机位置进行比较,试验结果表明,该定位解算算法具有良好的定位效果。 相似文献
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Bandyopadhayay T. Guha A. DasGupta A. Banerjee P. Bose A. 《Electronics letters》1997,33(12):1010-1011
The effect of ionospheric scintillation on navigational accuracy with the GPS (Global Positioning System) in the equatorial region is presented. The accuracy of position fixing with the GPS as indicated by the PDOP (position dilution of precision) factor is degraded when the raypath from the satellite shows deep fading. It is understood that navigation, particularly using a moderately sophisticated GPS receiver, in the equatorial zone will be severely affected during maximum sunspot number years 相似文献
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采用卫星仿真工具包对全球卫星导航系统包括GPS、Galileo、Compass等导航卫星星座的地面站天线方位、俯仰跟踪特性进行了仿真分析,以大口径地面接收天线为例讨论了可行的地面站天线座架形式和跟踪体制.并综合常规卫星通信抛物面天线精度分析方法和测控雷达天线的精度分析方法对跟踪精度进行了系统的分析,分析结果可作为今后类... 相似文献
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为了能完成卫星定位,需要对卫星信号进行捕获、追踪。文中针对带有C/A码的L1频段的GPS信号进行定位研究,捕获能从接收的信号中粗略地估算出可见卫星的信号参数,用于帮助接收机初始化跟踪环路,并开始跟踪信号。码跟踪和载波跟踪模块则将这些参数细化,跟踪后即可解调出导航数据。仿真结果表明,算法可准确快速地从32颗卫星中捕捉和跟踪预定的卫星信号。 相似文献
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针对全球低轨卫星通信系统的动态性引起的反向缝区域覆盖问题,采用辐射场到地球覆盖区的转换方法,仿真分析了单个卫星服务区为圆形、椭圆和矩形时的全球覆盖情况,并采用椭圆子波束排布对椭圆和矩形的卫星覆盖进行了分析。结果表明,在不增加波束个数的前提下,采用波导缝隙阵的长椭圆子波束,单个卫星矩形覆盖可以有效解决卫星反向缝区域无法完全覆盖的问题。通过对多星影响下的载干比统计方法进行分析,得出这种卫星波束排布方法满足卫星通信的要求,为低轨卫星的天线波束设计提供了理论参考。 相似文献
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针对单GPS定位系统存在定位盲区而无法实现定位的难题,结合基于DTMB标准的数字电视定位系统的优势,给出GPS与DTMB融合定位新方法,研究多种信号源参与定位的导航精度变化,并仿真分析4种不同场景下精度因子变化大小,通过理论分析和仿真实验证明了DTMB信号的参与改善了卫星的几何布局,减少了精度因子值,同时当参与的DTMB信号越多时,精度变化曲线更加平滑,精度因子取值平均在3左右,可以满足实际导航定位中对精度的需要。 相似文献