GPS RTK技术在滩涂测量中的应用

在黄河口大面积滩涂测量中，采用了GPS实时动态测量(RTK)技术，体现出定位精度高、完成数据采集快、外界因素影响小的特点，成为测量自动化系统的重要组成部分。介绍了控制点精度检核、碎部测量精度比对结果。     

实时动态差分GPS与全站仪配合在航道测量中的应用

通过理论分析与应用实践，探讨了实时动态差分全球定位系统(GPSRTK)与全站仪相配合测量的解决方案、实测技术以及操作过程中的主要问题。分析了在航道测量中的仪器设备、人员分工与环境利用的协调配合方法，既保证了测图精度，又提高了工作效率和经济效益，得出了有益的结论。     

回声测深仪在水下地形测量中的应用

本文在介绍回声测深仪基本工作原理的同时,介绍了回声测深仪在杭州湾口外一拟建大型码头下地形测量的一个应用实例。     

利用GPS导航信号进行水下地形测量的时间同步

介绍了应用GPS接收机输出的导航信号用于水下地形测量时间同步的原理，并分别讨论了用于模拟测深仪、数字化／模拟测深仪和数字测深仪的同步方法。     

DGPS在航道的水下地形与水深测量中的应用示例

ＧＰＳ动态实时差分定位模式具有精度高,性能可靠,使用方便等优点,它在许多领域都展示了广阔的应用前景,本文将以ＤＧＰＳ在航道的水下地形与不深测量方面的具体应用为例予以简单介绍,代与同行交流。     

GPS高精度动态测量

高精度动态测量是近年来发展起来的GPS新技术,用于大比例尺测图、港口测量、施工测量等工程中。本文就高精度动态测量中的几个关键问题,如:电文发送速率、电离层效应改正等进行了论述,最后给出为高精度动态测量设置的Type18—Type21四组电文格式和含义。     

上海市滩涂水下地形测量研究

针对上海市滩涂水下地形测量工作的历史与现状,详细介绍了滩涂水下地形的测量方法、技术标准以及测绘成果的应用,说明了水下地形测量工作在水利事业中发挥的重要作用,并对更好地提高测绘精度提出了建议,展望了滩涂水下地形测绘的未来发展。     

基于PPK无验潮的水下地形测量技术研究

随着载波相位差分技术的发展,RTK(Real Time Kinematic)三维水深测量已经广泛应用于水下地形测量中。RTK技术需要建立实时数据链接传输差分数据,当数据链接丢失时,定位精度会严重下降。针对此问题,本文研究了一种基于后处理动态差分无需实时数据链接的PPK(Post Processing Kinematic)定位技术,并通过静态和动态比测的方法,对不同GNSS系统及其组合解算策略进行了精度和稳定性测试,最后在杭州湾河口进行了实际应用。测试结果表明,PPK获取的结果具有良好的稳定性,定位精度能满足实际工作需要;实际应用结果表明基于PPK的无验潮水下地形测量技术具有广泛的应用前景。     

DGPS RTK技术在无验潮水下地形测量中的应用初探

本文简要介绍了DGPS RTK技术的基本原理和作业流程，阐明了该技术在无验潮水下地形测量中的适用性，并以除六泾水文大断面的测量为例介绍了利用该技术进行工程实测的过程，通过对实测数据成果的分析，得出一些有益的结论。     

RTK GPS在无验潮水深测量中的应用

介绍了应用全球定位系统实时动态测量（RTK GPS）技术进行无验潮水深测量的基本方法，并在实际工作中进行了验证。     

RTK GPS在海岸工程中的应用

随着GPS技术的发展，具有RTK功能的GPS接收机不但在平面位置上可以达到厘束级，而且以WGS84为参考椭球的垂直高程也可以达到厘束级，因而被广泛地应用于海岸带测量中。本文介绍了RTKGPS在海域勘界、无验潮模式水深测量方面的一些具体应用。     

双频GPS PPK技术在沿岸海道测量中的应用

通过介绍NovAtel OEM4高精度双频GPS和所采用的动态测量后处理(PPK)技术工作原理,论述了沿岸海道测量机动作业系统的设备组成、作业原理、测量实施、数据处理以及技术指标等,明确了PPK基准站的设立条件、方法和要求,并结合试验和外业工作实际进行讨论。     

基于GPS的水下导航算法误差仿真研究

首先介绍了水下导航算法,采用GPS和水下参量测算相结合的方案,即当运行器在水下运行时,利用电子罗盘测量运行器的相对航向,水流传感器测算运行器的相对速度大小,利用学习阶段计算出海水流速,在水下运行器潜行时进行船位推算导航,用GPS精准的定位信号进行导航误差的校正。此算法精度的高低很大程度上取决于用来进行水下参量测算的传感器和用来方位校准的GPS。文中从各个传感器的误差着手,通过模拟仿真详细分析了电子罗盘、水流传感器和GPS的误差对导航精度的影响,对工程应用具有实际的指导意义。     

GPS输出的NMEA 0183信号的时间特性分析

为判断GPS接收机输出的NMEA0183信号是否可作为水下地形测量的同步信号，对多种CPS接收机输出的NMEA0183信号的时间特性进行了测试与分析。     

GPS RTK技术在舰船抗冲击试验中的应用

在舰船实船海上抗冲击试验中,需要对爆源与被试舰的相对位置关系进行实时定位监测。对基于GPSRTK技术的试验定位系统的设计思路、工作原理、数据处理方法、组成与实现等方面进行了阐述,最后介绍了系统应用效果。     

白噪声Kalman滤波模型在GPS单向授时中的应用

全球定位系统(GPS)的应用越来越广泛,尤其是高精度的星载原子钟使得授时的精度得到了很大的提高。针对GPS授时过程中接收机受到各种噪声的影响,利用Kalman滤波原理,建立状态方程和观测方程,对噪声进行分类并加以讨论。运用Kalman滤波原理对接收机钟差数据进行分析,计算结果表明Kalman滤波可提高GPS单向授时精度。     

Ambiguity Recovery Using the Triple-Differenced Carrier Phase Type Approach for Long-Range GPS Kinematic Positioning

Precise, long-range GPS kinematic positioning to centimeter accuracy requires that carrier phase ambiguities be resolved correctly during an initialization period, and subsequently to recover the “lost" ambiguities in the event of a cycle slip. Furthermore, to maximize navigational efficiency, ambiguity resolution and carrier phase-based positioning need to be carried out in real-time. Due to the presence of the ionospheric signal delay, satellite orbit errors, and the tropospheric delay, so-called absolute ambiguity resolution “on-the-fly” for long-range applications becomes very difficult, and largely impossible. However, all of these errors exhibit a high degree of spatial and temporal correlation. In the case of short-range ambiguity resolution, because of the high spatial correlation, their effect can be neglected, but their influence will dramatically increase as the baseline length increases. On the other hand, between discrete trajectory epochs, they will still exhibit a large degree of similarity for short time spans. In this article, a method is described in which similar triple-differenced observables formed between one epoch with unknown ambiguities and another epoch with fixed ambiguities can be used to derive relative ambiguity values, which are ordinarily equal to zero (or to the number of cycles that have slipped when loss-of-lock occurred). Because of the temporal correlation characteristics of the error sources, the cycle slips can be recovered using the proposed methodology. In order to test the performance of this algorithm an experiment involving the precise positioning of an aircraft, over distances ranging from a few hundred meters up to 700 kilometres, was carried out. The results indicate that the proposed technique can successfully resolve relative ambiguities (or cycle slips) over long distances in an efficient manner that can be implemented in real-time.     

Ambiguity Recovery Using the Triple-Differenced Carrier Phase Type Approach for Long-Range GPS Kinematic Positioning

Precise, long-range GPS kinematic positioning to centimeter accuracy requires that carrier phase ambiguities be resolved correctly during an initialization period, and subsequently to recover the “lost" ambiguities in the event of a cycle slip. Furthermore, to maximize navigational efficiency, ambiguity resolution and carrier phase-based positioning need to be carried out in real-time. Due to the presence of the ionospheric signal delay, satellite orbit errors, and the tropospheric delay, so-called absolute ambiguity resolution “on-the-fly” for long-range applications becomes very difficult, and largely impossible. However, all of these errors exhibit a high degree of spatial and temporal correlation. In the case of short-range ambiguity resolution, because of the high spatial correlation, their effect can be neglected, but their influence will dramatically increase as the baseline length increases. On the other hand, between discrete trajectory epochs, they will still exhibit a large degree of similarity for short time spans. In this article, a method is described in which similar triple-differenced observables formed between one epoch with unknown ambiguities and another epoch with fixed ambiguities can be used to derive relative ambiguity values, which are ordinarily equal to zero (or to the number of cycles that have slipped when loss-of-lock occurred). Because of the temporal correlation characteristics of the error sources, the cycle slips can be recovered using the proposed methodology. In order to test the performance of this algorithm an experiment involving the precise positioning of an aircraft, over distances ranging from a few hundred meters up to 700 kilometres, was carried out. The results indicate that the proposed technique can successfully resolve relative ambiguities (or cycle slips) over long distances in an efficient manner that can be implemented in real-time.