共查询到20条相似文献，搜索用时 46 毫秒
1.
分析了GPS高程信号和Heave信号的频段特征，利用数字信号处理技术，提取了GPS高程和Heave中的有效频段信号，合成了一个全新的信号。该合成信号能够全面反映多波束换能器的实际垂直运动，并能够克服传统多波束测量和数据处理方法的缺陷，大大提高了多波束在垂直方向的成果精度。实验证明了该方法的正确性和可行性。 相似文献
2.
对RTK高程和Heave信号在合成之前进行了预处理，确保了短周期内两者监测尺度和时间上的一致；然后利用数字信号处理技术实现这两个信号的融合；并通过一个实验对信号合成方法的精度进行了全面的分析和评估，认为该方法可以达到约6～7cm的精度，将传统多波束数据处理方法的精度提高了1倍。 相似文献
3.
利用GPS载波相位差分测量技术，借助时间偏差改正、姿态改正、高程转换、信号处理和吃水改正，获得了测船处精密在航潮位。该方法已在几个GPS在航潮位测量实验中得到了验证，并取得了理想的结果。 相似文献
4.
介绍了一种基于平均相关器的GPS信号快速捕获算法，通过VHDL语言描述在FPGA上实现了该算法。平均相关器是一种将输入的5000点GPS样本信号平均化为1024点样本，然后通过FFT方法实现GPS信号快速捕获的基带相关器。这种相关器可以一步搜索到所有可能的码相位偏移，大大提高了捕获速度，比较好地满足了实时处理的要求。 相似文献
5.
基于GPS新型L5信号的地表雪深反演研究 总被引：1，自引：0，他引：1
利用GPS多路径反射信号测量地表雪深具有全天候和高时空分辨率的特点,因此其可作为一种代替气象站监测雪深的新手段。然而,先前大多数研究仅使用了GPS L1和L2C波段信噪比数据探测积雪深度。为验证新型的L5信号在雪深反演方面的优越性,本文阐述了GPS-R技术反演雪深的原理,利用Lomb-Scargle周期图法所处理的受积雪表层影响的信噪比数据计算了频谱振幅强度,通过获取频谱特征值与天线高度的关系求解雪深值,最后分别与L1反演结果和实测雪深数据进行了对比。试验结果表明：与现有的GPS-R测量雪深结果相比,利用新型的L5反射信号反演地表雪深的精度更佳;采用GPS-R技术探测雪深对把握测站区域内的雪深变化情况和淡水资源储量具有重要价值。 相似文献
6.
采用GPS监测运营期大跨度桥梁时,受到交通载荷和观测噪声的影响,GPS监测序列中的振动信号(mm级)完全被湮没,如何从监测序列中提取桥梁变形信息及其振动特性是桥梁健康检测的重要内容。文中利用EMD方法对GPS监测序列进行处理,得到一定数量的本征模态函数(IMF),选取特定的IMF做信号重构和功率谱分析,得到桥梁变形信息和振动特性,相较于传统FFT方法,能准确识别结构振动频率,同时提取变形特征。 相似文献
7.
无验潮模式下的GPS水下地形测量技术 总被引：1，自引：2，他引：1
传统的水下地形测量模式定型于利用GPS测定水底点的平面位置,利用测深仪测定水底点的深度,附之以瞬时潮位资料,获得点位的高程。这种模式在上述条件具备的情况下,可取得完满的结果。但当验潮条件不具备时,该模式将不能获得测点的高程。为了弥补这一缺陷,简化工作流程,提高水下地形测量的精度,本文提出了一种无验潮模式下的水下地形测量思想,该思想不用专门测定潮位,而直接利用GPS的RTK测量技术,辅之以姿态测量和补偿,从而获得高精度的水底点高程。该方法被验证是正确的,希望进一步推广应用。 相似文献
8.
面向遥感的GNSS反射信号接收处理系统及实验 总被引：3，自引：0，他引：3
提出了一种新的GNSS-R信号接收处理系统（GNSS-Rreceiver system,GRrSv.2）的结构及信号处理方法。该系统可同时针对直射和反射的GNSS信号协同处理,并输出可配置延迟和多普勒的二维相关值矩阵。为了验证系统的性能,进行了针对海洋和陆地遥感的机载和岸基验证实验,并给出了初步的实验结果。 相似文献
9.
弱GPS信号捕获算法及其仿真研究 总被引：1，自引：0，他引：1
为满足低信噪比环境下的导航需要,介绍了一种基于改进循环相关的GPS基带信号捕获算法。本文借助于GPS信号基带数学模型以及FFT技术,从理论层面上对捕获算法的信号处理流程以及捕获性能进行了分析;并利用真实GPS基带数据对算法在低信噪比环境下的检测概率和捕获能力进行了重点仿真,仿真结果显示算法在低信噪比环境下是有效的,能够提高低信噪比环境下的检测概率和提高GPS接收机的检测灵敏度。 相似文献
10.
Kunlun Yan Nesreen I. Ziedan Hongping Zhang Wenfei Guo Xiaoji Niu Jingnan Liu 《GPS Solutions》2016,20(2):225-237
An open loop tracking architecture, which tracks GPS signals under weak and challenging conditions, is analyzed. The in-phase and quadrature-phase integration pair is regarded as a single tone complex signal. An FFT-based method is used as a frequency discriminator to estimate the Doppler frequency residual of the single tone signal. Another FFT-based method applies complex squaring to eliminate the effect of the navigation data bits polarities. The performance of the FFT-based discriminators is assessed in three criteria. Those criteria are the signal strength and dynamic range that can be tracked and the accuracy of the estimated Doppler frequency. In addition, the performance of the discriminators is analyzed to provide the theoretical and simulated peak detection probability. The results indicate that the FFT discriminator can track signals about 5 dB weaker than the signals that can be tracked by the complex squared FFT discriminator. In a quasi-static environment, the Doppler frequency residual can be assumed to be around zero, which can enable the FFT-based discriminators to track signals with approximately 2 dB less power. Moreover, the performance of the FFT-based discriminators is compared with the performance of two other frequency discriminators, namely the fast–slow and power-based. The comparison results indicate that these two frequency discriminators give higher frequency estimation accuracy, but they have a narrower dynamic range. 相似文献
11.
Annual deformation signals from homogeneously reprocessed VLBI and GPS height time series 总被引：3，自引：3，他引：0
Volker Tesmer Peter Steigenberger Markus Rothacher Johannes Boehm Barbara Meisel 《Journal of Geodesy》2009,83(10):973-988
The first part of this paper compares homogeneously reprocessed Very Long Baseline Interferometry (VLBI) and Global Positioning
System (GPS) long-term height series from 1994 to 2007. The data analysis used fully adapted state-of-the-art models (like
VMF1 and a priori zenith delays from ECMWF) for the GPS and VLBI processing. The series are compared in terms of long-term
non-linear behaviour, harmonic and mean annual signals (not necessarily of harmonic nature). The similarity between both techniques
is very good (especially the mean annual signals), which is assumed to be due to the adapted models and consistent reprocessing
of both series. As two almost independent observing techniques see the same annually recurring signals at almost all co-located
sites, we expect a good geophysical interpretability as integral vertical deformation. For the second part of this paper,
the height time series of 161 suitable GPS sites (of the same solution as before) are used to determine a harmonic and a mean
annual signal for each of them. Comparing the annual signals for this big dataset visually to GRACE-determined load deformations
described in other publications, we find good agreement. This puts emphasis to the assumption that our height data have a
lot of potential to be interpreted as geophysical signals. Out of these 161, 131 are grouped to 55 clusters, if at least two
nearby (some thousand kilometres) sites show similar mean annual signals, which are thus confirmed to be real regional deformation,
not local or technical artefacts. These 55 signals are presented on a “world map” of regional average mean annual height signals,
as easy-to-handle tool to validate geophysical models. The data of these measured regional mean annual signals can be downloaded
from a web-page for numerical analysis. 相似文献
12.
Hung Lee Jinling Wang Chris Rizos Dorota Grejner-Brzezinska Charles Toth 《GPS Solutions》2002,6(1-2):34-46
This paper discusses the introduction of pseudolites (ground-based GPS-like signal transmitters) into existing integrated
GPS/INS systems in order to provide higher availability, integrity, and accuracy in a local area. Even though integrated GPS/INS
systems can overcome inherent drawbacks of each component system (line-of-sight requirement for GPS, and INS errors that grow
with time), performance is nevertheless degraded under adverse operational circumstances. Some typical examples are when the
duration of satellite signal blockage exceeds an INS bridging level, resulting in large accumulated INS errors that cannot
be calibrated by GPS. Such a scenario, unfortunately, is a common occurrence for certain kinematic applications. To address
such shortcomings, both pseudolite/INS and GPS/pseudolite/INS integration schemes are proposed here. Typically, the former
is applicable for indoor positioning where the GPS signal is unavailable for use. The latter would be appropriate for system
augmentation when the number and geometry of visible satellites is not sufficient for accurate positioning or attitude determination.
In this paper, some technical issues concerned with implementing these two integration schemes are described, including the
measurement model, and the appropriate integration filter for INS error estimation and correction through GPS and pseudolite
(PL) carrier phase measurements. In addition, the results from the processing of simulated measurements, as well as field
experiments, are presented in order to characterize the system performance. As a result, it has been established that the
GPS/PL/INS and PL/INS integration schemes would make it possible to ensure centimeter-level positioning accuracy even if the
number of GPS signals is insufficient, or completely unavailable.
Electronic Publication 相似文献
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14.
Multipath disturbance is one of the most important error sources in high-accuracy global positioning system (GPS) positioning and navigation. A new data filtering method, based on the Vondrak filter and the technique of cross-validation, is developed for separating signals from noise in data series, and applied to mitigate GPS multipath effects in applications such as deformation monitoring. Both simulated data series and real GPS observations are used to test the proposed method. It is shown that the method can be used to successfully separate signals from noise at different noise levels, and for varying signal frequencies as long as the noise level is lower than the magnitude of the signals. A multipath model can be derived, based on the current-day GPS observations, with the proposed method and used to remove multipath errors in subsequent days of GPS observations when taking advantage of the sidereal day-to-day repeating characteristics of GPS multipath signals. Tests have shown that the reduction in the root mean square (RMS) values of the GPS errors ranges from 20% to 40% when the method is applied. 相似文献
15.
Local geoid determination combining gravity disturbances and GPS/levelling: a case study in the Lake Nasser area, Aswan, Egypt 总被引：1，自引：0，他引：1
C. C. Tscherning Awar Radwan A. A. Tealeb S. M. Mahmoud M. Abd El-Monum Ramdan Hassan I. El-Syaed K. Saker 《Journal of Geodesy》2001,75(7-8):343-348
The use of GPS for height control in an area with existing levelling data requires the determination of a local geoid and
the bias between the local levelling datum and the one implicitly defined when computing the local geoid. If only scarse gravity
data are available, the heights of new data may be collected rapidly by determining the ellipsoidal height by GPS and not
using orthometric heights. Hence the geoid determination has to be based on gravity disturbances contingently combined with
gravity anomalies. Furthermore, existing GPS/levelling data may also be used in the geoid determination if a suitable general
gravity field modelling method (such as least-squares collocation, LSC) is applied. A comparison has been made in the Aswan
Dam area between geoids determined using fast Fourier transform (FFT) with gravity disturbances exclusively and LSC using
only the gravity disturbances and the disturbances combined with GPS/levelling data. The EGM96 spherical harmonic model was
in all cases used in a remove–restore mode. A total of 198 gravity disturbances spaced approximately 3 km apart were used,
as well as 35 GPS/levelling points in the vicinity and on the Aswan Dam. No data on the Nasser Lake were available. This gave
difficulties when using FFT, which requires the use of gridded data. When using exclusively the gravity disturbances, the
agreement between the GPS/levelling data were 0.71 ± 0.17 m for FFT and 0.63 ± 0.15 for LSC. When combining gravity disturbances
and GPS/levelling, the LSC error estimate was ±0.10 m. In the latter case two bias parameters had to be introduced to account
for a possible levelling datum difference between the levelling on the dam and that on the adjacent roads.
Received: 14 August 2000 / Accepted: 28 February 2001 相似文献
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小波包多阈值去噪法及其在形变分析中的应用 总被引：1，自引：0，他引：1
在GPS变形监测领域,传统的小波去噪只保留低频上的有用信息,很容易去掉中频以及高频上的有用信息。小波包分析方法是近几年发展起来的一种新的小波分析方法,它同时考虑了各个频段上的有用信息,因此是一种更为精细的去噪方法。小波包去噪的关键是对小波包分解系数选取合适的阈值准则并进行阈值处理,但传统的小波包去噪并没有对此进行充分的研究。本文针对传统小波、小波包分析的不足,提出了一种基于频率顺序并依据信息类型分段的多阈值准则小波包去噪法。通过理论分析与实际应用,结果表明新方法能够高效剔除各频段的噪声,同时当采样频率较低时能有效保留去噪信号中频率高达10-1 Hz数量级的有用信息,其去噪能力优于传统的小波、小波包等其它去噪方法,因此可以广泛应用于高精度GPS变形监测领域中。 相似文献
19.
GPS坐标转换方法对于GPS空间定位系统至关重要。目前已有很多方法被提出用于转换GPS坐标,但效果并不是很显著。究其原因,是因为大多数都存在模型误差和投影误差。针对目前方法的不足,本文利用深度学习对非结构化数据处理的优势,提出了一种基于卷积神经网络(CNN)的GPS坐标转换方法。该方法将GPS数据转化为非结构化图片数据,以其作为CNN的输入层来训练GPS坐标转换模型,这样能够最小化满足对数据的预处理要求,无监督地从数据中学习出有效特征。试验结果表明,该方法与传统坐标转换方法相比,具有更高的转换精度。 相似文献