共查询到17条相似文献,搜索用时 166 毫秒
1.
2.
3.
传统的微波调制信号质量评估需要将微波信号变频到中频后进行处理,变频处理会引起非线性失真问题,而且星间链路信号许多关键质量参数如相位一致性、相关损失、I/Q(Inphase/Quadrature,同相/正交)支路功率比等无法用传统评估方法完成,针对这些问题,提出了采用软件无线电技术的导航卫星星间链路信号质量评估算法,利用高速采样器对导航卫星的星间链路信号进行直接射频采样,在数字域对星间链路信号进行相关接收和解调,实现所有关键质量参数的评估.该方法避免了使用变频器带来的附加失真,采用该方法完成实际星载设备的信号质量评估的结果表明,该评估算法精度高,能满足导航卫星星间链路设备信号质量参数评估要求. 相似文献
4.
5.
星点坐标辅助的全天区三角形星图识别算法 总被引:1,自引:1,他引:0
随着当前星敏感器视场(FOV)的增大,探测能力的提高,一帧图中拍摄到的恒星更多。但是受星敏感器光谱范围的限制及空间环境干扰影响,星等测试精度一般不高于0.2 mV。为了充分发挥当前星敏感器视场和探测能力的优势,并避免星等误差的影响,提高全天区星图识别算法在线应用的适用性,提出了一种星点坐标辅助的全天区三角形星图识别算法。该方法采用"全局初步搜索识别—局部精细匹配验证—最优结果选取"的算法思想。首先,根据星敏感器探测到的极限星等范围构建导航星表,选取亮星构建角距星表,既确保了星表的完备性,又有利于充分利用星敏感器的探测能力。然后,在三角形约束条件下进行角距匹配识别,得到一个或多个导航三角形,在该识别环节提出了非线性矢量法查找星表,既提高了定位精度,又能采用单精度数据类型降低存储空间。最后,提出局部天区星点坐标匹配算法进一步消除冗余匹配,同时又识别出视场内更多的观测星,有利于提高识别率和定姿精度。试验结果表明,与其他一些经典的星图识别算法相比,所提算法在识别率和星表容量方面更有优势。识别率可达99.9%,且随着星等的增加,存储容量增加的最少。所提算法更加适于大视场、高星等敏感范围的星敏感器在线应用。 相似文献
6.
7.
北斗高动态双频相对定位技术 总被引:1,自引:0,他引:1
"北斗"卫星导航定位系统可以进行高精度单点定位和相对定位。本文针对该系统提出了一种相对定位选星策略,分析了几种双频组合方法及适用范围,给出了一种利用B1和B3频率进行双频载波相位差分的方法,并针对具体应用进行了仿真器环境试验验证,为"北斗"卫星导航定位系统建成后高精度相对定位应用提供参考。 相似文献
8.
月球探测器高精度导航技术是确保月球探测任务顺利实施的关键技术之一。当前,大多数月球探测器都是利用地面无线电进行导航和控制,但存在可测控弧段短、易受干扰等局限性,且对于月球背面探测,存在无法直接测控的不足。针对上述问题,提出了一种新的基于天文测角/单程无线电差分测距/差分测速的月球探测器组合导航方法。该方法使用了天文星光角距、探测器接收到的来自地面站或中继星的单程无线电时间差分测距和时间差分多普勒测速3种量测信息,可有效抑制星上时钟和频谱仪的时间和频率测量误差。收敛后的平均位置和速度估计误差分别为902.7 m和0.12 m/s,最大的位置和速度估计误差分别为1 548.2 m和0.24 m/s。仿真分析结果表明该方法具有较高自主导航精度。 相似文献
9.
10.
《航空学报》2015,(7)
复合载波导航信号(NSCC)作为一种新型的导航增强信号体制,其独特的多载波结构和灵活的体制参数设计,使之具备良好的导航增强效能。同时,以上典型信号特征也使得传统的导航信号同步算法对其不再适用。针对复合载波导航信号结构特征和体制参数设计特点,提出了一种基于多载波架构的恒虚警联合捕获方法。该方法利用复合载波导航信号各子载波信号功率进行自适应检测门限设置,并利用各子载波频点间隔信息进行并行检测,然后根据联合策略做出判决,提升了捕获性能和捕获效率。理论分析及仿真实验均表明,在低信噪比(SNR)情况下,本文所提出的联合捕获方法的捕获性能明显优于单载波捕获算法,并缩短了平均捕获时长。 相似文献
11.
12.
Samaan M.A. Mortari D. Junkins J.L. 《IEEE transactions on aerospace and electronic systems》2005,41(4):1246-1254
Star identification can be accomplished by several different available algorithms that identify the stars observed by a star tracker. However, efficiency and reliability remain key issues and the availability of new active pixel cameras requires new approaches. Two novel algorithms for recursive mode star identification are presented here. The first approach is derived by the spherical polygon search (SP-search) algorithm, it was used to access all the cataloged stars observed by the sensor field-of-view (FOV) and recursively add/remove candidate cataloged stars according to the predicted image motion induced by camera attitude dynamics. Star identification is then accomplished by a star pattern matching technique which identifies the observed stars in the reference catalog. The second method uses star neighborhood information and a catalog neighborhood pointer matrix to access the star catalog. In the recursive star identification process, and under the assumption of "slow" attitude dynamics, only the stars in the neighborhood of previously identified stars are considered for star identification in the succeeding frames. Numerical tests are performed to validate the absolute and relative efficiency of the proposed methods. 相似文献
13.
Jie Jiang Guangjun Zhang Xinguo Wei Xiao Li 《Aerospace and Electronic Systems Magazine, IEEE》2009,24(9):23-33
A rapid star tracking algorithm is proposed. In order to speed up the tracking, three techniques includng parallel star centroiding, sorting, and star catalogue partition are designed for three time-consuming portions in tracking algorithms. The parallel star centroiding is implemented with Field Programmable Gate Array (FPGA) which avoid image storage and transmission. Update rate of star sensor is improved. Sorting star coordinates in star image plane, and then matching, which avoid matching between stars with a long distance in image plane. Star catalogue partition divides the celestial sphere into many small partitions. In star mapping, guide stars are searched in the partitions near the direction of star sensor's boresight is not in the whole celestial sphere and therefore reduced the total number of searched guide stars. The software and hardware performance of tracking algorithms are simulated. Tracking robustness and the tracking speed comparison are tested in the software simulation. In hardware tests, the tracking time in every step is obtained. 相似文献
14.
15.
16.