共查询到20条相似文献,搜索用时 31 毫秒
1.
Quality assessment of GPS rapid static positioning with weighted ionospheric parameters in generalized least squares 总被引:3,自引:2,他引:1
Pawel Wielgosz 《GPS Solutions》2011,15(2):89-99
Precise GPS positioning requires the processing of carrier-phase observations and fixing integer ambiguities. With increasing
distance between receivers, ambiguity fixing becomes more difficult because ionospheric and tropospheric effects do not cancel
sufficiently in double differencing. A popular procedure in static positioning is to increase the length of the observing
session and/or to apply atmospheric (ionospheric) models and corrections. We investigate the methodology for GPS rapid static
positioning that requires just a few minutes of dual-frequency GPS observations for medium-length baselines. Ionospheric corrections
are not required, but the ionospheric delays are treated as pseudo-observations having a priori values and respective weights.
The tropospheric delays are reduced by using well-established troposphere models, and satellite orbital and clock errors are
eliminated by using IGS rapid products. Several numerical tests based on actual GPS data are presented. It is shown that the
proposed methodology is suitable for rapid static positioning within 50–70 km from the closest reference network station and
that centimeter-level precision in positioning is feasible when using just 1 min of dual-frequency GPS data. 相似文献
2.
H. Kutterer 《Journal of Geodesy》1998,72(2):51-63
GPS has become an essential tool for the precise determination of point positions. Since GPS campaigns for geodynamic purposes
– such as the monitoring of recent crustal movements – require major financial efforts, it is essential to ensure already
in the planning phase a good network quality and the attainment of the scientific goals in a reasonable time. The paper outlines
an operationally oriented procedure for these purposes based on the simulation and processing of GPS carrier-phase observations.
Sensitivity analysis techniques are applied to describe both the network strain as it may be induced by gross errors and the
detectability of point movements between two sessions or two campaigns. In addition, the eigenvalue decomposition of the variance-covariance
matrix of the GPS coordinates will be used to identify weakly determined network components. The design of the SCAR Epoch
95 Campaign GPS network is discussed throughout the paper. It was realized in the Antarctic summer 1994/1995 on the Antarctic
peninsula.
Received: 30 November 1995 / Accepted: 1 July 1997 相似文献
3.
Time-relative positioning is a recent method for processing GPS phase observations. The operational method undertaken in this
paper consists of the following steps: first, recording phase observations at a station of known coordinates; second, moving
the GPS receiver to an unknown station (which can be located up to a few hundred meters away, dependint on what type of transportation
– e. g., walking, motorcycle – is available) while continuously observing carrier phases; and, third, recording phase observations
at a second station of unknown coordinates with a single GPS receiver. To obtain the position of the unknown station relative
to the first (known) station, the processing method uses combined observations taken at two different epochs and two different
stations with the same receiver. For this reason, the errors that vary between two epochs must be taken into account in an
appropriate way, especially errors in satellite clock corrections and ephemerides, and errors related to tropospheric and
ionospheric delays. Ionospheric modeling using IONEX files (the ionospheric maps calculated by the International GPS Service)
was also tested to correct L1 phase observations. This method has been used to calculate short vectors with an accuracy of
a few centimeters (for a processing interval of 30 s) using a single civil GPS receiver. ? 2001 John Wiley & Sons, Inc. 相似文献
4.
This paper illustrates the surveys and the results obtained in an experiment whose goal is to evaluate the Global Positioning
System (GPS) sensitivity and accuracy for deformation control on non-permanent network of different extensions. To this aim
a high-precision device was properly built to set up known displacements along three orthogonal axes of a GPS antenna. One
of the antennas in the considered GPS networks was moved according to centimeter and sub-centimeter displacements; after careful
GPS data processing, it was evaluated whether these simulated deformations were correctly a posteriori detected and at which
probability level. This experiment was carried out both on a local (baselines ranging between 3 and 30 km) and on a regional
(baselines ranging between 300 and 600 km) GPS network. The results show that in the local network it is possible to identify
the displacements at a level of 10 mm in height and at a level of 5 mm in horizontal position. The analysis of the regional
network showed that it is fundamental to investigate new strategies to model the troposphere; in fact, it is necessary to
improve the precision of the height in order to correctly identify displacements lower than 60–80 mm; on the contrary, horizontal
displacements can be evidenced at the level of 20 mm.
Received: 27 April 1998 / Accepted: 14 December 1998 相似文献
5.
Performance of Singapore Integrated Multiple Reference Station Network (SIMRSN) for RTK Positioning 总被引:1,自引:0,他引:1
Conventional RTK positioning is usable, but requires the use of a local base station. It is also restricted by the effects
of the de-correlate atmospheric refraction on the GPS signal, which limits the use of the RTK positioning up to distances
of 10–15 km from the reference station to the user. With a multiple reference station network approach, precise RTK positioning
capability may be extended for a much larger area. The Singapore Integrated Multiple Reference Station Network (SIMRSN) has
been established for this purpose. Using an existing method termed linear combination method, the multiple reference station
network corrections are generated for the user on an epoch by epoch, satellite-by-satellite basis. A residual-based adaptive
Kalman filter is proposed to improve network correction availability. The VRS concept is used to transmit corrections to the
user for RTK positioning. Field tests were conducted to demonstrate the general performance of SIMRSN. The tests confirmed
that RTK positioning within a multiple reference station network can provide the user with better than 3 cm in horizontal
position, the height accuracy is in the range of 1–7 cm, and the average TTF (Time To Fix) are 46 and 76 s during GLC station
and LPR station tests, respectively. With this highly efficient survey technique, the user needs only to be equipped with
a single GPS receiver. This reduces equipment and manpower costs compared with traditional RTK positioning using a specially
set up reference station. The multiple reference station framework also paves the way for various other applications beyond
the traditional surveying profession.
Electronic Publication 相似文献
6.
Apropos laser tracking to GPS satellites 总被引:3,自引:0,他引:3
. Laser tracking to GPS satellites (PRN5 and 6) provides an opportunity to compare GPS and laser systems directly and to combine
data of both in a single solution. A few examples of this are given in this study. The most important results of the analysis
are that (1) daily SLR station coordinate solutions could be generated with a few cm accuracy; (2) coordinates of nine stations
were determined in a 2.3-year-long arc solution; (3) the contribution of laser data on the `SLR-GPS' combined orbit, resulting
from the simultaneous processing of SLR and GPS data, is significant and (4) laser-only orbits have an accuracy of 10–20 cm,
1-day predictions of SLR orbits differ from IGS orbits by about 20–40 cm, 2-day predictions by 50–60 cm.
Received: 1 October 1996 / Accepted: 14 February 1997 相似文献
7.
GPS signal diffraction modelling: the stochastic SIGMA-δ model 总被引:1,自引:0,他引:1
The SIGMA-Δ model has been developed for stochastic modelling of global positioning system (GPS) signal diffraction errors
in high precision GPS surveys. The basic information used in the SIGMA-Δ model is the measured carrier-to-noise power-density
ratio (C/N0). Using the C/N0 data and a template technique, the proper variances are derived for all phase observations. Thus the quality of the measured
phase is automatically assessed and if phase observations are suspected to be contaminated by diffraction effects they are
weighted down in the least-squares adjustment. The ability of the SIGMA-Δ model to reduce signal diffraction effects is demonstrated
on two static GPS surveys as well as on a kinematic high-precision GPS railway survey. In cases of severe signal diffraction
the accuracy of the GPS positions is improved by more than 50% compared to standard GPS processing techniques.
Received: 27 July 1998 / Accepted: 1 March 1999 相似文献
8.
An algorithm for very accurate absolute positioning through Global Positioning System (GPS) satellite clock estimation has
been developed. Using International GPS Service (IGS) precise orbits and measurements, GPS clock errors were estimated at
30-s intervals. Compared to values determined by the Jet Propulsion Laboratory, the agreement was at the level of about 0.1 ns
(3 cm). The clock error estimates were then applied to an absolute positioning algorithm in both static and kinematic modes.
For the static case, an IGS station was selected and the coordinates were estimated every 30 s. The estimated absolute position
coordinates and the known values had a mean difference of up to 18 cm with standard deviation less than 2 cm. For the kinematic
case, data obtained every second from a GPS buoy were tested and the result from the absolute positioning was compared to
a differential GPS (DGPS) solution. The mean differences between the coordinates estimated by the two methods are less than
40 cm and the standard deviations are less than 25 cm. It was verified that this poorer standard deviation on 1-s position
results is due to the clock error interpolation from 30-s estimates with Selective Availability (SA). After SA was turned
off, higher-rate clock error estimates (such as 1 s) could be obtained by a simple interpolation with negligible corruption.
Therefore, the proposed absolute positioning technique can be used to within a few centimeters' precision at any rate by estimating
30-s satellite clock errors and interpolating them.
Received: 16 May 2000 / Accepted: 23 October 2000 相似文献
9.
Pierre Bosser Olivier Bock Christian Thom Jacques Pelon Pascal Willis 《Journal of Geodesy》2010,84(4):251-265
This paper investigates the impact of rapid small-scale water vapor fluctuations on GPS height determination. Water vapor
measurements from a Raman lidar are used for documenting the water vapor heterogeneities and correcting GPS signal propagation
delays in clear sky conditions. We use data from four short observing sessions (6 h) during the VAPIC experiment (15 May–15
June 2004). The retrieval of wet delays from our Raman lidar is shown to agree well with radiosonde retrievals (bias and standard
deviation (SD) were smaller than 1 and 2.8 mm, respectively) and microwave radiometers (from two different instruments, bias
was 6.0/−6.6 mm and SD 1.3/3.8 mm). A standard GPS data analysis is shown to fail in accurately reproducing fast zenith wet
delay (ZWD) variations. The ZWD estimates could be improved when mean post-fit phase residuals were removed. Several methodologies
for integrating zenith lidar observations into the GPS data processing are also presented. The final method consists in using
lidar wet delays for correcting a priori the GPS phase observations and estimating a scale factor for the lidar wet delays
jointly with the GPS station position. The estimation of this scale factor allows correcting for a mis-calibration in the
lidar data and provides in the same way an estimate of the Raman lidar instrument constant. The agreement of this constant
with an independent determination using radiosonde data is at the level of 1–4%. The lidar wet delays were derived by ray-tracing
from zenith pointing measurements: further improvement in GPS positioning is expected from slant path lidar measurements that
would properly account for water vapor anisotropy. 相似文献
10.
GPS形变监测网基线处理中系统误差的分析 总被引:18,自引:3,他引:18
分析了高精度GPS形变监测网基线处理中系统误差产生的原因,分类及其对基线处理的影响,并在此基础上提出消除和削弱这些系统误差影响的一些原则和算法。 相似文献
11.
An approach to GLONASS ambiguity resolution 总被引:9,自引:2,他引:7
J. Wang 《Journal of Geodesy》2000,74(5):421-430
When processing global navigation satellite system (GLONASS) carrier phases, the standard double-differencing (DD) procedure
cannot cancel receiver clock terms in the DD phase measurement equations due to the multiple frequencies of the carrier phases.
Consequently, a receiver clock parameter has to be set up in the measurement equations in addition to baseline components
and DD ambiguities. The resulting normal matrix unfortunately becomes singular. Methods to deal with this problem have been
proposed in the literature. However, these methods rely on the use of pseudo-ranges. As pseudo-ranges are contaminated by
multi-path and hardware delays, biases in these pseudo-ranges are significant, which may result in unreliable ambiguity resolution.
A new approach is addressed that is not sensitive to the biases in the pseudo-ranges. The proposed approach includes such
steps as converting the carrier phases to their distances to cancel the receiver clock errors, and searching for the most
likely single-differenced (SD) ambiguity. Based on the results from the theoretical investigation, a practical procedure for
GLONASS ambiguity resolution is presented. The initial experimental results demonstrate that the proposed approach is useable
in cases of GLONASS and combined global positioning system (GPS) and GLONASS positioning.
Received: 19 August 1998 / Accepted: 12 November 1999 相似文献
12.
A global positioning system (GPS)-based online control and alarm system (GOCA) for monitoring of three-dimensional movements
has been developed at the Karlsruhe University of Technology. The GOCA hardware consists of an array of GPS sensors and communication
units to be placed in the monitoring area. The hardware-dependent control software communicates with the GPS sensors and provides
the GPS baseline data and covariance information to the GOCA deformation analysis software. The GOCA center, which comprises
both the control software and the GOCA software, may be linked – for example, over a long distance – to another personal computer
(PC) that serves as a remote control station. GOCA is able to provide the full capabilities of classical deformation analysis
online (with stations grouped into stable points and moving object points). Both types of points may be occupied either continuously
or over short periods at different times. The object points are determined with respect to the stable points. A network adjustment
is performed for each interval of data collection, and the coordinate and covariance information may optionally be transformed
into a specific reference system (e. g., the building system). Unstable reference points are to be detected by statistical
tests. The estimated object point time series are filtered with respect to gross errors using robust estimation techniques.
Online filters are used to smooth the time series data of critical displacements and to predict other deformation functions.
The time series data, as well as prediction results, are displayed graphically for each object point. An example concerning
the online monitoring of a slag heap in a coal-mining area is included. ? 2000 John Wiley & Sons, Inc. 相似文献
13.
Automated GPS Data Analysis Service 总被引:5,自引:1,他引:4
James F. Zumberge 《GPS Solutions》1999,2(3):76-78
Automatic analysis of geodetic-quality GPS data is available with the use of e-mail and ftp (file transfer program) as an
interface to a computer at the Jet Propulsion Laboratory (JPL), where precise transmitter parameters – GPS ephemerides and
clock errors – are computed regularly. The interface is such that e-mail from an external user causes the JPL computer to
fetch the user's data. The computer than analyzes the data, and places the results in an area accessible to the user. An e-mail
to the user gives information on the location of the analysis results, which the user can subsequently fetch. Operations on
the JPL computer are entirely automatic, and require essentially no labor. ? 1999 John Wiley & Sons, Inc. 相似文献
14.
应用网络工程GPS基准站每周的数据,按非基准方法求得区域解和全球解,分析研究了基准站坐标位置及速度场的变化规律,并给出了站坐标和速度场精度的统计分析结果。结果显示,坐标分量的变化趋势为线性,坐标残差的变化为随机曲线,可靠地剔除野点后,速度场信息及其精度可靠且优于点位坐标精度。 相似文献
15.
Robert Odolinski 《GPS Solutions》2012,16(2):147-155
Temporal correlation in network real-time kinematic (RTK) data exists due to unmodeled multipath and atmospheric errors, in
combination with slowly changing satellite constellation. If this correlation is neglected, the estimated uncertainty of the
coordinates might be too optimistic. In this study, we compute temporal correlation lengths for network RTK positioning, i.e.,
the appropriate time separation between the measurements. This leads to more realistic coordinate uncertainty estimates, and
an appropriate surveying strategy to control the measurements can be designed. Two methods to estimate temporal correlation
lengths are suggested. Several monitor stations that utilize correction data from two SWEPOSTM Network RTK services, a standard service and a project-adapted service with the mean distance between the reference stations
of approximately 70 and 10–20 km, are evaluated. The correlation lengths for the standard service are estimated as 17 min
for the horizontal component and 36–37 min for the vertical component. The corresponding estimates for the project-adapted
service are 13–17 and 13–16 min, respectively. According to the F test, the proposed composite first-order Gauss–Markov autocovariance function shows a significantly better least-squared
fit to data compared to the commonly used one-component first-order Gauss–Markov model. A second suggested method is proposed
that has the potential of providing robust correlation lengths without the need to fit a model to the computed autocovariance
function. 相似文献
16.
GPS measurements of ocean loading and its impact on zenith tropospheric delay estimates: a case study in Brittany, France 总被引:1,自引:0,他引:1
S. Vey E. Calais M. Llubes N. Florsch G. Woppelmann J. Hinderer M. Amalvict M. F. Lalancette B. Simon F. Duquenne J. S. Haase 《Journal of Geodesy》2002,76(8):419-427
The results from a global positioning system (GPS) experiment carried out in Brittany, France, in October 1999, aimed at
measuring crustal displacements caused by ocean loading and quantifying their effects on GPS-derived tropospheric delay estimates,
are presented. The loading effect in the vertical and horizontal position time series is identified, however with significant
disagreement in amplitude compared to ocean loading model predictions. It is shown that these amplitude misfits result from
spatial tropospheric heterogeneities not accounted for in the data processing. The effect of ocean loading on GPS-derived
zenith total delay (ZTD) estimates is investigated and a scaling factor of 4.4 between ZTD and station height for a 10° elevation
cut-off angle is found (i.e. a 4.4-cm station height error would map into a 1-cm ZTD error). Consequently, unmodeled ocean
loading effects map into significant errors in ZTD estimates and ocean loading modeling must be properly implemented when
estimating ZTD parameters from GPS data for meteorological applications. Ocean loading effects must be known with an accuracy
of better than 3 cm in order to meet the accuracy requirements of meteorological and climatological applications of GPS-derived
precipitable water vapor.
Received: 16 July 2001 / Accepted: 25 April 2002
Acknowledgments. The authors are grateful to H.G. Scherneck for fruitful discussions and for his help with the ocean loading calculations.
They thank H. Vedel for making the HIRLAM data available; D. Jerett for helpful discussions; and the city of Rostrenen, the
Laboratoire d'Océanographie of Concarneau, and the Institut de Protection et de S?reté Nucléaire (BERSSIN) for their support
during the GPS measurement campaign. Reviews by C.K. Shum and two anonymous referees significantly improved this paper. This
work was carried out in the framework of the MAGIC project (http://www.acri.fr/magic), funded by the European Commission,
Environment and Climate Program (EC Contract ENV4-CT98–0745).
Correspondence to: E. Calais, Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN 47907-1397, USA. e-mail:
ecalais@purdue.edu Tel. : +1-765-496-2915; Fax:+1-765-496-1210 相似文献
17.
我国GPS跟踪站数据处理与时间序列特征分析 总被引:1,自引:0,他引:1
应用国内GPS跟踪站7a的观测数据,分析研究跟踪站坐标位置变化规律,并给出了站坐标和速度场精度的统计分析结果,同时介绍了国内GPS基准站的数据处理方法。通过对时间序列进行分析研究表明,GPS基准站的时间序列具有一定的周期性,高程分量的周期性最为明显,并且时间序列的时频特性表现出明显的区域性。 相似文献
18.
C. Vigny J. Chéry T. Duquesnoy F. Jouanne J. Ammann M. Anzidei J.-P. Avouac F. Barlier R. Bayer P. Briole E. Calais F. Cotton F. Duquenne K. L. Feigl G. Ferhat M. Flouzat J.-F. Gamond A. Geiger A. Harmel M. Kasser M. Laplanche M. Le Pape J. Martinod G. Ménard B. Meyer J.-C. Ruegg J.-M. Scheubel O. Scotti G. Vidal 《Journal of Geodesy》2002,76(2):63-76
The Western Alps are among the best studied collisional belts with both detailed structural mapping and also crustal geophysical
investigations such as the ECORS and EGT seismic profile. By contrast, the present-day kinematics of the belt is still largely
unknown due to small relative motions and the insufficient accuracy of the triangulation data. As a consequence, several tectonic
problems still remain to be solved, such as the amount of N–S convergence in the Occidental Alps, the repartition of the deformation
between the Alpine tectonic units, and the relation between deformation and rotation across the Alpine arc. In order to address
these problems, the GPS ALPES group, made up of French, Swiss and Italian research organizations, has achieved the first large-scale
GPS surveys of the Western Alps. More than 60 sites were surveyed in 1993 and 1998 with a minimum observation of 3 days at
each site. GPS data processing has been done by three independent teams using different software. The different solutions
have horizontal repeatabilities (N–E) of 4–7 mm in 1993 and 2–3 mm in 1998 and compare at the 3–5-mm level in position and
2-mm/yr level in velocity. A comparison of 1993 and 1998 coordinates shows that residual velocities of the GPS marks are generally
smaller than 2 mm/yr, precluding a detailed tectonic interpretation of the differential motions. However, these data seem
to suggest that the N–S compression of the Western Alps is quite mild (less than 2 mm/yr) compared to the global convergence
between the African and Eurasian plate (6 mm/yr). This implies that the shortening must be accomodated elsewhere by the deformation
of the Maghrebids and/or by rotations of Mediterranean microplates. Also, E–W velocity components analysis supports the idea
that E–W extension exists, as already suggested by recent structural and seismotectonic data interpretation.
Received: 27 November 2000 / Accepted: 17 September 2001 相似文献
19.
20.
Assessment of ECMWF-derived tropospheric delay models within the EUREF Permanent Network 总被引:1,自引:0,他引:1
The Global Positioning System (GPS) observations from the EUREF Permanent Network (EPN) are routinely analyzed by the EPN
analysis centers using a tropospheric delay modeling based on standard pressure values, the Niell Mapping Functions (NMF),
a cutoff angle of 3° and down-weighting of low elevation observations. We investigate the impact on EPN station heights and
Zenith Total Delay (ZTD) estimates when changing to improved models recommended in the updated 2003 International Earth Rotation
and Reference Systems Service (IERS) Conventions, which are the Vienna Mapping Functions 1 (VMF1) and zenith hydrostatic delays
derived from numerical weather models, or the empirical Global Mapping Functions (GMF) and the empirical Global Pressure and
Temperature (GPT) model. A 1-year Global Positioning System (GPS) data set of 50 regionally distributed EPN/IGS (International
GNSS Service) stations is processed. The GPS analysis with cutoff elevation angles of 3, 5, and 10° revealed that changing
to the new recommended models introduces biases in station heights in the northern part of Europe by 2–3 mm if the cutoff
is lower than 5°. However, since large weather changes at synoptic time scales are not accounted for in the empirical models,
repeatability of height and ZTD time series are improved with the use of a priori Zenith Hydrostatic Delays (ZHDs) derived
from numerical weather models and VMF1. With a cutoff angle of 3°, the repeatability of station heights in the northern part
of Europe is improved by 3–4 mm. 相似文献