共查询到19条相似文献,搜索用时 187 毫秒
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在精密定时中普遍采用铷原子频标,虽然铷原子频标的频率稳定度要远优于晶体振荡器,但仍属于二级频率标准,需要用一级频标对其定时校准,比较麻烦。若能采用新的技术对其进行在线自动校准,不仅可以降低运营成本,也可以提高设备的利用率。本文介绍了一种简便的采用GPS对铷原子频标自动校准的方法,供大家参考。 相似文献
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分析了频率捷变雷达信号源边跟踪边校准方法存在的缺陷,提出了一种新型实时动态频率校准方法,在信号源边跟踪边校准工作模式上,进一步提高了信号源的频率跟踪精度和稳定工作时间,并大大减小了漏跟概率. 相似文献
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1 问题的提出 JJG545-88<频标比对器检定规程>是目前现行通用的规程,它的适用对象是新制造的、使用中的和修理后的PO7系列频标比对器. 笔者对于规程中的带宽检定方法以及带宽计算公式存有疑问.为方便说明问题,现将JJG545-88检定规程中有关测量带宽的检定方法和计算公式转述如下: 相似文献
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633nm碘稳定激光器作为长度基(标)准的比对测量 总被引:1,自引:0,他引:1
简述作为长度基(标)准用的633nm碘稳定激光器的技术指标以及它的测量方法,文中以作者所进行的国际和国内比对中的测量结果为例,给出了这类激光器可以复现的频率或波长不确定度。 相似文献
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精密单点定位(PPP)时间传递技术是国际时间比对的重要手段之一,为协调世界时的计算做出巨大贡献。为探究多系统融合PPP时间频率传递性能,选取3个国际授时实验室的测站数据组成2条链路,采用8种实验模式对比分析单系统、双系统、三系统和四系统PPP时间频率传递性能。实验结果表明:各多系统组合较单GPS系统在可见星数上均有较大提升,且极大改善了钟差精度因子,增加了时间比对结果的稳健性和可靠性。在时间传递稳定性方面:对于453.4 km的PTBB-BRUX链路,较单GPS系统,双系统中GPS/BDS组合提升效果最优,提升率约为10.39%,三系统中GPS/GLONASS/BDS组合提升率最优,约为11.86%,四系统组合提升率为11.98%,可从0.046 7 ns提升至0.041 1 ns;对于8 031.8 km的PTBB-NIST链路,GPS/BDS组合提升率约为4.89%,GPS/GLONASS/BDS组合提升率约为5.49%,四系统组合提升率为5.79%,可从0.114 0 ns提升至0.107 4 ns。在频率传递稳定度方面:在前10 000 s内双系统组合平均提升17.6%,三系统... 相似文献
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对远程计量校准技术进行了全面的论述,阐述了远程校准的概念、远程校准技术的优点,以及开展远程校准技术的意义和国际上的最新动态.最后介绍了一种将互联网技术应用到现场计量校准工作中的远程计量校准模式. 相似文献
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The Standoff Land Attack Missile (SLAM) is a worldwide, all-weather, precision-strike weapon system deployed from carrier-based aircraft. In the primary mode of operation, target location and other mission data are generated from intelligence sources available on the aircraft carrier and loaded into the missile prior to aircraft takeoff. After missile launch, the SLAM inertial navigation system (INS) guides the missile along the planned trajectory. Updating the missile INS from the Global Positioning System (GPS) during flight provides precise midcourse navigation and enhances target acquisition by accurate, on-target pointing of the SLAM Maverick seeker. The GPS/INS avionics and software integration used for SLAM are described in detail, along with some of the design tradeoffs that led to the approach. The avionics configuration integrates the Harpoon midcourse guidance unit, which includes a strapdown inertial sensor package and digital processor, with a Rockwell-Collins single-channel, sequential GPS receiver processor unit (RPU), a derivative of the GPS phase-III user equipment. In addition to the GPS receiver elements the RPU contains the navigation processor, which executes the SLAM navigation, Kalman filter algorithms, and other guidance algorithms including seeker pointing. Flight-test results of the SLAM GPS-aided INS are also included 相似文献
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Preliminary results of a simulation effort to evaluate the requirements and feasibility of the global positioning system (GPS) as a civil air navigation system are presented. Evaluation is made of GPS requirements, from operational considerations, such as application to nonprecision approaches. The conceptual low-cost GPS receiver simulated here does not correct for the ionospheric or trophospheric delay, is sequential in nature, tracks only four satellites, and is not mechanized to make independent range rate measurements based on the Doppler shift of the GPS carrier frequency. The proposed GPS system has significantly different performance characteristics from the presently used VHF omnidirectional range (VOR) solidus distance-measuring equipment (DME) system. The GPS is a low signal level system and many have a relatively slow data rate due to the low-cost sequential receiver design. The results indicate that although the conceptual low-cost GPS receiver/ navigator is potentially more accurate than a VOR, the accuracy may degrade during aircraft turns and satellite shielding periods. 相似文献
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GPS/INS uses low-cost MEMS IMU 总被引:3,自引:0,他引:3
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GPS在多航天器相对导航和姿态确定中的应用 总被引:6,自引:0,他引:6
研究了GPS在一类没有结构和力约束,但存在运动约束的多航天器系统中的应用。首先分析了GPS在该系统中应用的模式和方案。重点研究了相对GPS(RGPS)导航和GPS姿态确定的方法和算法。然后提出了GPS在该系统中应用的总体结构和功能结构。最后对GPS在该系统中应用的选星、滤波器设计、误差消除等问题进行了讨论。研究结果有助于GPS在多航天器系统中应用的标准化。 相似文献
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本文讨论GPS/惯性组合两种方式的优缺点。并以GPS伪距和伪距率与惯导组合为例,按GPS测量误差的不同,以及使用差分机等情况,仿真计算了机载使用的组合导航性能,进行了详细的精度分析。结果表明,这种组合的导航精度比GPS和惯导各自的导航精度高。在采用差分GPS机与惯导组合后,位置误差将进一步减少,使组合导航具有开辟例如飞机进场着陆等新的使用领域的可能性。 相似文献
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Airborne radar relies on Built-in-Test (BIT) for fault detection, fault isolation and system calibration. The capability of BIT is often limited by space, weight, size and cost considerations. Furthermore, the radar does not have a test target that will allow BIT to perform in flight, closed-loop functional test of the complete radar system. This paper describes a fiber-optic based radar test target unit that provides a delayed replica of the transmitted radar signal. The unit will intercept a small amount of radar-transmitted energy, delay it in the fiber, then feed it back into the radar producing a calibrated “echo” at a predetermined radar range. The unit can be installed as part of the airborne radar. The details on the design and testing of a proof-of-concept unit are also given 相似文献
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基于激光扫描和计算机视觉的无人机全天候自主着陆导引技术 总被引:2,自引:1,他引:1
为了解决基于GPS导航的无人机受他国控制和易受干扰的潜在危险问题,提出以GPS导航系统为主,以捷联惯性导航结合主动式红外激光扫描定位及计算机视觉识别着陆跑道为辅的无人机导航和着陆精确导引新技术,实现无人机全天候的自主精确着陆。提出了该技术的具体工作原理和工作过程,对激光扫描系统的工作原理和扫描模型及扫描参数的确定、着陆点的激光反射装置的确定、着陆点坐标与着陆跑道方向的确定问题和防止发生由其它反射物或红外光源误导的措施等问题进行了分析和研究。 相似文献