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1.
于奇 《测绘与空间地理信息》2021,44(5):41-44
高精度的卫星钟差是进行精密定位服务的关键,对于实时无模糊度精密单点定位来说,需要对广播星历卫星钟差进行历元差分来实现单站位移的解算,但钟差精度的历元间变化会对解算结果产生影响.对星载原子钟的短期稳定性进行分析,可以了解不同卫星钟差的时频特性,对研究广播星历钟差精度变化情况、提高单站位移解算精度具有重要的意义.本文利用单站GPS数据进行星间相对钟差的估计,然后基于相对钟差估计结果对星载RB钟的短期稳定性进行快速分析.通过实测的GPS数据进行实验,结果表明利用单站GPS数据估计的3 h的相对钟差精度要优于0.5 ns;阿伦方差计算结果表明BlockⅡF卫星RB钟短期稳定性最优,BlockⅡRM卫星和BlockⅡR卫星RB钟的短期稳定性基本相当,但要低于BlockⅡF卫星. 相似文献
2.
卫星钟差是影响卫星定位精度的重要误差源之一,而实时精密单点定位又要求卫星钟差实时更新。卫星钟差的解算可通过非差模型或历元差分模型实现,但非差模型涵盖较多的载波相位模糊度参数,相比消掉模糊度参数的历元差分模型,计算效率要慢许多。历元差分模型仅利用载波相位观测量就可获得高精度卫星钟差历元间差,恢复后的卫星钟差仍可达到一定精度水平。利用历元差分模型可实现北斗卫星钟差的实时解算,试验结果表明:通过滤波得到的卫星钟差历元间差精度优于0.02 ns,恢复后的卫星钟差精度优于0.25 ns. 相似文献
3.
GPS/GLONASS卫星钟差联合估计过程中，由于GLONASS系统采用频分多址技术区分卫星信号，因而会产生频率间偏差（IFB）[1]。本文在GPS/GLONASS卫星定轨过程中的IFB参数特性分析的基础上，引入IFB参数，实现顾及频率间偏差的GPS/GLONASS卫星钟差实时估计。同时，为解决实时估计中待估参数过多导致的实时性较弱等问题，基于非差伪距观测值和历元间差分相位观测值改进实时估计数学模型，实现多系统卫星钟差的联合快速估计。结果表明：GPS/GLONASS联合估计时需引入IFB参数并优化其估计策略，采用MGEX和iGMAS跟踪站的实测数据进行实时钟差解算，快速估计方法可实现1.6 s逐历元快速、高精度估计，与GBM提供的最终精密卫星钟差相比，GPS卫星钟差实时精度约为0.210 ns，GLONASS卫星约为0.298 ns。 相似文献
4.
GNSS增强系统中精密实时钟差高频估计及应用研究 总被引：1，自引：0，他引：1
GNSS星基差分增强系统依赖于实时轨道及钟差增强信息。本文主要研究多GNSS实时精密钟差估计模型,在传统非差基础上优化待估参数,实现了一种高效的Multi-GNSS实时钟差简化估计模型。基于PANDA软件开展了实时轨道数据处理与分析,经过验证可获得的GPS/北斗MEO/Galileo实时轨道径向精度1~5cm,北斗GEO/IGSO卫星径向精度约10cm。分析发现本文优化的实时钟差简化估计模型单历元解算效率较高,可应用于实时钟差增强信息高频(如1Hz)更新,且解算获得的实时钟差不存在常偏为绝对钟差;基于实时轨道,通过该模型可获得实时钟差精度GPS约0.22ns,北斗GEO约0.50ns、IGSO/MEO约0.24ns,Galileo约0.32ns。在此基础上,利用目前所获取的MultiGNSS实时数据流搭建了Multi-GNSS全球实时增强原型系统,并基于互联网实时播发增强信息,可初步实现实时PPP厘米级服务、伪距米级导航定位服务。 相似文献
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实时钟差产品是高精度广域差分位置服务(亚米级、分米级、厘米级)的基础产品,本文针对BDS/GPS轨道精度差异,设计了一种顾及轨道精度差异观测权函数,优化了实时钟差估计的随机模型,在此基础上基于非差法实现了BDS/GPS联合的实时钟差估计。采用MGEX和iGMAS跟踪站的实时观测数据进行实时钟差解算,并与iGMAS产品综合中心提供的事后精密钟差产品进行了比较分析。结果表明:基于该方法估计的钟差精度对单GPS、单BDS和BDS/GPS融合都有提高,其中BDS钟差精度整体较GPS更为显著,提高幅度约12.8%,其中IGSO/MEO更为突出,提高幅度约20%,验证了方法的有效性。 相似文献
7.
《测绘地理信息》2020,(3)
基于GNSS(global navigation satellite system)非差观测量,利用双线程钟差加密的方法,本文实现了导航卫星实时钟差的逐秒更新。通过选取全球均匀分布的76个参考站对四系统钟差进行联合估计,并从实时轨道精度,解算效率,钟差精度和精密单点定位(precision point positioning,PPP)定位结果对该系统进行分析和评估。结果表明,GPS预报轨道径向精度为2.3 cm,GLONASS和Galileo预报轨道径向精度为3 cm和3.5 cm,北斗GEO、IGSO、MEO卫星预报轨道径向精度分别为31 cm,17 cm和5.3 cm;钟差统计结果表明,GPS实时钟差精度优于0.2 ns,GLONASS钟差精度优于0.4 ns,Galileo钟差精度优于0.3 ns,受轨道影响,北斗GEO实时钟差精度为0.6～1.0 ns,IGSO钟差精度为0.4～0.7 ns,MEO钟差精度为0.3～0.4 ns;PPP定位结果表明,解算钟差定位精度与事后钟差定位结果相当,平面精度在3 cm以下,高程精度在5 cm以下。 相似文献
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卫星钟差的难预测性是影响实时高精度定位的重要因素之一。为快速获得高精度位置或对流层等信息，在非差观测模型的基础上，本文提出了一种延迟量约1 h的近实时钟差估计策略，该策略主要包含超快速轨道解算和钟差估计两部分。经验证，预报部分第2~5 h的GPS轨道三维平均精度为3.85 cm，BDS GEO和IGSO+MEO轨道三维平均精度分别为81.4和21.74 cm。基于超快速轨道可获得近实时钟差精度GPS为0.054 ns，BDS为0.12 ns。最后通过BDS+GPS静态PPP试验验证了轨道和钟差的可用性。 相似文献
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利用GPS进行变形监测在各个领域中的应用越来越广泛。如何利用GPS的观测数据进行变形量的高精度单历元解算是一个难点。国内学者提出了单历元似单差算法进行小变形的单历元解算,但需要利用其他方法对接收机钟差进行计算。根据站间单差观测方程之间的相关性,可以将接收机钟差之差及其他一些通过站间单差未能消除的未知量作为一个未知参数在单历元观测方程中与变形量一同求解。利用该方法对小变形试验数据的解算结果精度达到了毫米级。 相似文献
11.
Xiaopeng Li 《Journal of Geodesy》2011,85(9):597-605
Combining data from a Strapdown Inertial Navigation System and a Differential Global Positioning System (SINS/DGPS) has shown
great promise in estimating gravity on moving platforms. Previous studies on a ground-vehicle system obtained 1–3 mGal precision
with 2 km spatial resolution. High-accuracy Inertial Measurement Units (IMU) and cm-level positioning solutions are very important
in obtaining mGal-level gravity disturbance estimates. However, these ideal configurations are not always available or achievable.
Because the noise level in the SINS/DGPS gravimetric system generally decreases with an increase of speed and altitude of
the platform, the stringent constraints on the IMU and GPS may be relieved in the airborne scenario. This paper presents an
investigation of one navigation-grade and one tactical-grade IMU for the possibility of low-cost INS/GPS airborne gravimetry.
We use the data collected during the Gravity-Lidar Study of 2006 (GLS06), which contains aerogravity, GPS, and INS along the
northern coastline of the Gulf of Mexico. The gravity disturbance estimates from the navigation-grade IMU show 0.5–3.2 mGal
precision compared with the onboard gravimeter’s measurements and better than 3 mGal precision compared with the upward continued
surface control data. Due to relatively large (240 s) smoothing window, the results have about 34 km along-track resolution.
But the gravity estimates from the tactical-grade IMU have much poorer precisions. Nonetheless, useful contributions from
the tactical-grade IMU could be extracted for longer wavelengths. 相似文献
12.
M. S. Senobari 《Journal of Geodesy》2010,84(5):277-291
A method for airborne vector gravimetry has been developed. The method is based on developing the error dynamics equations
of the INS in the inertial frame where the INS system errors are estimated in a wave estimator using inertial GPS position
as update. Then using the error-corrected INS acceleration and the GPS acceleration in the inertial frame, the gravity disturbance
vector is extracted. In the paper, the focus is on the improvement of accuracy for the horizontal components of the airborne
gravity vector. This is achieved by using a decoupled model in the wave estimator and decorrelating the gravity disturbance
from the INS system errors through the estimation process. The results of this method on the real strapdown INS/DGPS data
are promising. The internal accuracy of the horizontal components of the estimated gravity disturbance for repeated airborne
lines is comparable with the accuracy of the down component and is about 4–8 mGal. Better accuracy (2–4 mGal) is achieved
after applying a wave-number correlation filter (WCF) to the parallel lines of the estimated airborne gravity disturbances. 相似文献
13.
Flight test results from a strapdown airborne gravity system 总被引：3，自引：0，他引：3
In June 1995, a flight test was carried out over the Rocky Mountains to assess the accuracy of airborne gravity for geoid
determination. The gravity system consisted of a strapdown inertial navigation system (INS), two GPS receivers with zero baseline
on the airplane and multiple GPS master stations on the ground, and a data logging system. To the best of our knowledge, this
was the first time that a strapdown INS has been used for airborne gravimetry. The test was designed to assess repeatability
as well as accuracy of airborne gravimetry in a highly variable gravity field. An east-west profile of 250 km across the Rocky
Mountains was chosen and four flights over the same ground track were made. The flying altitude was about 5.5km, i.e., between
2.5 and 5.0km above ground, and the average flying speed was about 430km/h. This corresponds to a spatial resolution (half
wavelength of cutoff frequency) of 5.07.0km when using filter lengths between 90 and 120s. This resolution is sufficient for
geoid determination, but may not satisfy other applications of airborne gravimetry. The evaluation of the internal and external
accuracy is based on repeated flights and comparison with upward continued ground gravity using a detailed terrain model.
Gravity results from repeated flight lines show that the standard deviation between flights is about 2mGal for a single profile
and a filter length of 120s, and about 3mGal for a filter length of 90s. The standard deviation of the difference between
airborne gravity upward continued ground gravity is about 3mGal for both filter lengths. A critical discussion of these results
and how they relate to the different transfer functions applied, is given in the paper. Two different mathematical approaches
to airborne scalar gravimetry are applied and compared, namely strapdown inertial scalar gravimetry (SISG) and rotation invariant
scalar gravimetry (RISG). Results show a significantly better performance of the SISG approach for a strapdown INS of this
accuracy class. Because of major differences in the error model of the two approaches, the RISG method can be used as an effective
reliability check of the SISG method. A spectral analysis of the residual errors of the flight profiles indicates that a relative
geoid accuracy of 23cm over distances of 200km (0.1 ppm) can be achieved by this method. Since these results present a first
data analysis, it is expected that further improvements are possible as more refined modelling is applied.
Received: 19 August 1996 / Accepted: 12 May 1997 相似文献
14.
Although airborne gravimetry is now considered a fully operational technique, errors due to motion compensation using differential
GPS (DGPS) continue to influence both its accuracy and the range of applications in which it can be used. In typical medium-resolution
applications such as airborne geoid mapping, errors due to DGPS contribute considerably to the error budget of an airborne
gravity system. At the same time, efforts to increase the resolution of such systems for demanding applications such as resource
exploration remain impedded by errors in DGPS.
This article has three objectives. The first one is to compare eight industrially relevant DGPS software packages for the
determination of aircraft acceleration. The second objective is to analyze and quantify the effect that each relevant portion
of the DGPS error budget has on the determination of acceleration. Using data sets that represent a wide range of operational
conditions, this is done in the frequency domain over a range of frequencies corresponding to spatial resolution as high as
450 m. The third objective is to use that information to recommend and demonstrate approaches that optimize the estimation
of aircraft acceleration for determining the geoid and for resource exploration.
It is shown, for example, that the time of day in which the survey is carried out and the dynamic characteristics of the aircraft
being used are two of the most crucial parameters for very high-resolution gravity field estimation. It is demonstrated that
when following the above-mentioned recommendations, agreements with ground daa of better than 1.5 and 2.5 mGal can be achieved
for spatial resolutions (half-wavelengths) of 2.0 and 1.4 km, respectively. ? 2002 Wiley Periodicals, Inc. 相似文献
15.
分别采用基于梯度、基于泊松积分和基于快速傅里叶变换（FFT）的地面重力向上延拓方案,并提出交叉检验方法估计地面重力数据误差及其空中误差传播,对毛乌素测区GT-2A航空重力测量系统采集的空中测线数据进行外符合精度评价。对比结果表明：地面重力格网插值误差和代表性误差对空中点的影响达到0.66~0.92 mGal（1 Gal=1×10-2 m/s2）,航空重力数据误差估计必须扣除这一影响;基于泊松积分和基于FFT的地面重力向上延拓方法能够客观评价航空重力观测值的外符合精度,二者表现相当;扣除地面重力误差影响后,在包含残余边界效应的情况下,毛乌素测区GT-2A航空重力空中测线重力扰动的外符合精度优于1.42 mGal。 相似文献
16.
目前,航空重力测量是快速获取陆地和近海区域高精度、高分辨率重力场信息的非常有效的技术手段,向下延拓则是其数据处理中的关键环节,直接影响到测量结果的进一步应用。本文在对传统最小二乘法、改进最小二乘法、Tikhonov正则化法等延拓模型进行数值分析的基础上,根据调和函数的基本特性,提出并建立了Poisson积分迭代法和改进Poisson积分迭代法延拓模型。实测航空和地面重力测量数据的试验结果表明,本文新建的Poisson积分迭代法和改进Poisson积分迭代法延拓模型精度相当,比传统最小二乘法延拓模型精度提高了15.26 mGal,比改进最小二乘法延拓模型精度提高了0.21 mGal,比Tikhonov正则化法延拓模型精度略低0.13 mGal,从而证明了本文所建模型的正确性和有效性。 相似文献
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Christopher Jekeli 《Journal of Geodesy》1992,66(1):54-61
The Global Positioning System (GPS) is considered in conjunction with a strapdown Inertial Measurement Unit (IMU) for measuring the gravity vector. A comparison of this system in space and on an airborne platform shows the relative importance of each system element in these two different acceleration environments. With currently available instrumentation, the acceleration measurement accuracy is the deciding factor in space, while on an Earth-bound (including airborne) platform, the attitude error of the IMU is most critical. A simulation shows that GPS-derived accelerations in space can be accurate to better than 0.1mgal for a 30s integration time, leading to estimates of 1° mean gravity anomalies on the Earth's surface with an accuracy of 4–5 mgal. On an airborne platform, the horizontal gravity estimation error is tightly coupled to the attitude error of the platform, which can only be bounded by external attitude updates. Horizontal gravity errors of 5mgal are achievable if the attitude is maintained to an accuracy of 1arcsec. 相似文献
20.
D. Sampietro M. Capponi A. H. Mansi A. Gatti P. Marchetti F. Sansò 《Journal of Geodesy》2017,91(5):535-545
Regional gravity field modelling by means of remove-compute-restore procedure is nowadays widely applied in different contexts: it is the most used technique for regional gravimetric geoid determination, and it is also used in exploration geophysics to predict grids of gravity anomalies (Bouguer, free-air, isostatic, etc.), which are useful to understand and map geological structures in a specific region. Considering this last application, due to the required accuracy and resolution, airborne gravity observations are usually adopted. However, due to the relatively high acquisition velocity, presence of atmospheric turbulence, aircraft vibration, instrumental drift, etc., airborne data are usually contaminated by a very high observation error. For this reason, a proper procedure to filter the raw observations in both the low and high frequencies should be applied to recover valuable information. In this work, a software to filter and grid raw airborne observations is presented: the proposed solution consists in a combination of an along-track Wiener filter and a classical Least Squares Collocation technique. Basically, the proposed procedure is an adaptation to airborne gravimetry of the Space-Wise approach, developed by Politecnico di Milano to process data coming from the ESA satellite mission GOCE. Among the main differences with respect to the satellite application of this approach, there is the fact that, while in processing GOCE data the stochastic characteristics of the observation error can be considered a-priori well known, in airborne gravimetry, due to the complex environment in which the observations are acquired, these characteristics are unknown and should be retrieved from the dataset itself. The presented solution is suited for airborne data analysis in order to be able to quickly filter and grid gravity observations in an easy way. Some innovative theoretical aspects focusing in particular on the theoretical covariance modelling are presented too. In the end, the goodness of the procedure is evaluated by means of a test on real data retrieving the gravitational signal with a predicted accuracy of about 0.4 mGal. 相似文献