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1.
Two methods for smoothing pseudorange observable by Carrier and Doppler are discussed. Then the procedure based on the RINEX observation files is tested using the Ashtech Z-XII3T geodetic receivers driven by a stable external frequency at UNSO. This paper proposes to adapt this procedure for the links between geodetic receivers, in order to take advantage of theP codes available onL1 andL2. This new procedure uses the 30-second RINEX observations files, the standard of the International GPS Service (IGS), and processes the ionosphere-free combination of the codesP1 andP2; the satellite positions are deduced from the IGS rapid orbits, available after two days. 相似文献
2.
The International Atomic Time scale (TAI) is computed by the Bureau International des Poids et Mesures (BIPM) from a set of
atomic clocks distributed in about 40 time laboratories around the world. The time transfer between these remote clocks is
mostly performed by the so-called GPS common view method: The clocks are connected to a GPS time receiver whose internal software
computes the offsets between the remote clocks and GPS time. These data are collected in a standard formal called CCTF. In
the present study we develop both the procedure and the software tool that allows us to generate the CCTF files needed for
time transfer to TAI, using RINEX files produced by geodetic receivers driven by an external frequency. The CCTF files are
then generated from the RINEX observation files. The software is freely available at ftp://omaftp.oma.be/dist/astro/time/RINEX_CCTF.
Applied to IGS (International GPS Service) receivers, this procedure will provide a direct link between TAI and the IGS clock
combination. We demonstrate here the procedure using the RINEX files from the Ashtech Metronome (ZXII-T) GPS receiver, to
which we apply the conventional analysis to compute the CCTF data. We compared these results with the CCTF files produced
by a time receiver R100-30T from 3S-Navigation. We also used this comparison with the results of a calibrated time receiver
to determine the hardware delay of the geodetic receiver. ? 2001 John Wiley & Sons, Inc. 相似文献
3.
We have used GLONASS P-code measurements from different geodetic GPS/GLONASS receivers involved in the IGEX campaign to perform
frequency/time transfer between remote clocks. GLONASS time transfer is commonly based on the clock differences between GLONASS
system time and the local clock computed by a time transfer receiver. We choose to analyze the raw P-code data available in
the RINEX files. This also allows working with the data from geodetic receivers involved in the IGEX campaign. As a first
point, we show that the handling of the external frequency in some of the IGEX receivers is not suited for time transfer applications.
We also point out that the GLONASS broadcast ephemerides give rise to a considerable number of outliers in the time transfer,
compared to the precise IGEX ephemerides. Due to receiver clock resets at day boundaries, which is a characteristic of the
R100 receivers from 3S-Navigation, continuous data sets exceeding one day are not available. Invthis context, it is therefore
impossible to perform RINEX-based precise frequency transfer with GLONASS P-codes on a time scale longer than one day. Because
the frequencies used by GLONASS satellites are different, the time transfer results must be corrected for the different receiver
hardware delays. After this correction, the final precision of our time transfer results corresponds to a root-mean-square
(rms) of 1.8 nanoseconds (ns) (maximum difference of 11.8 ns) compared to a rms of about 4.4 ns (maximum difference of 31.9
ns) for time transfer based on GPS C/A code observations. ? 2001 John Wiley & Sons, Inc. 相似文献
4.
A new plotting program for Windows-based TEQC users 总被引：1，自引：0，他引：1
Stephen Hilla 《GPS Solutions》2002,6(3):196-200
In a 1999 issue of GPS Solutions (Vol. 3, No. 1) Estey and Meertens describe a multi-purpose software toolkit for GPS and
GLONASS data called TEQC (pronounced "tek"). The program's name reflects its three main functions: translating, editing, and
quality checking. TEQC can be used on many different computer platforms, including Windows-based personal computers. This amazingly
capable program can be used for converting native binary files from a wide variety of GPS receivers into the standard Receiver
Independent Exchange Format (RINEX). It can also be used for editing and quality-controlling existing RINEX files. And it
can be used for generating plot files of several different quantities normally associated with satellite observations. This
article describes a new C/C++ program which gives Windows-based TEQC users increased flexibility for viewing and printing
TEQC plot files. The user can now specify a start and stop time for each plot, a subset of satellites to be plotted, labels
for the x- and y-axes, and a title to appear at the top of each plot. The new software converts the original "Compact Format"
plot files output by TEQC into PostScript files, which can then be viewed or printed. An additional benefit of PostScript
files is that they can be used to provide high-quality, high-resolution graphics for document publishing.
Electronic Publication 相似文献
5.
Recent studies have shown the capabilities of Global Positioning System (GPS) carrier phases for frequency transfer based
on the observations from geodetic GPS receivers driven by stable atomic clocks. This kind of receiver configuration is the
kind primarily used within the framework of the International GPS Service (IGS). The International GPS Service/Bureau International
des Poids et Mesures (IGS/BIPM) pilot project aims at taking advantage of these GPS receivers to enlarge the network of Time
Laboratories contributing to the realization of the International Atomic Time (TAI).
In this article, we outline the theory necessary to describe the abilities and limitations of time and frequency transfer
using the GPS code and carrier phase observations. We report on several onsite tests and evaluate the present setup of our
12-channel IGS receiver (BRUS), which uses a hydrogen maser as an external frequency reference, to contribute to the IGS/BIPM
pilot project.
In the initial experimental setup, the receivers had a common external frequency reference; in the second setup, separate
external frequency references were used. Independent external clock monitoring provided the necessary information to validate
the results. Using two receivers with a common frequency reference and connected to the same antenna, a zero baseline, we
were able to use the carrier phase data to derive a frequency stability of 6 × 10−16 for averaging times of one day. The main limitation in the technique originates from small ambient temperature variations
of a few degrees Celsius. While these temperature variations have no effect on the functioning of the GPS receiver within
the IGS network, they reduce the capacities of the frequency transfer results based on the carrier phase data. We demonstrate
that the synchronization offset at the initial measurement epoch can be estimated from a combined use of the code and carrier
phase observations. In our test, the discontinuity between two consecutive days was about 140 ps. ? 1999 John Wiley & Sons,
Inc. 相似文献
6.
Precise Point Positioning Using IGS Orbit and Clock Products 总被引：40，自引：11，他引：40
The contribution details a post-processing approach that used undifferentiated dual-frequency pseudorange and carrier phase
observations along with IGS procise orbit products, for stand-alone precise geodetic point positioning (static or kinematic)
with cm precision. This is possible if one takes advantage of the satellite clock estimates available with the satellite coordinates
in the IGS precise orbit products and models systematic effects that cause cm variations in the satelite to user range. This
paper will describe the approach, summarize the adjustment procedure, and specify the earth- and space-based models that must
be implementetd to achieve cm-level positioning in static mode. Furthermore, station tropospheric zenth path delays with cm
precision and GPS receiver clock estimates procise to 0.1 ns are also obtained. ? 2001 John Wiley & Sons, Inc. 相似文献
7.
Progress in Carrier Phase Time Transfer 总被引：1，自引：0，他引：1
Jim Ray Felicitas Arias Gérard Petit Tim Springer Thomas Schildknecht Jon Clarke Jan Johansson 《GPS Solutions》2001,4(4):47-54
The progress of the joint Pilot Project for time transfer, formed by the International GPS Service (IGS) and the Bureal International
des Poids et Mesures (BIPM), was recently reviewed. Three notable milestones were set. (1) The IGS will implement, at least
in a test mode, an internally realized time scale based on an integration of combined frequency standards within the IGS network.
This will eventually become the reference time scale for all IGS clock products (instead of the current GPS broadcast time).
(2) A new procedure for combined receiver and satellite clock products will be implemented officially in November 2000. Receiver
clocks are an entirely new product of the IGS. (3) The BIPM will coordinate an effort to calibrate all Ashtech Z12-T (and
possibly other) receivers suitable for time transfer applications, either differentially or absolutely. Progress reports will
be presented publicly in the spring 2001. ? 2001 John Wiley & Sons, Inc. 相似文献
8.
RINEX格式是GPS数据一种常用的标准数据格式,通用性强,利于多种型号的接收机联合作业,绝大多数商用软件都能处理。本文从生产实践出发,详细介绍了RINEX格式数据信息及常用的几种GPS接收机数据传输与转换方式,以及解算过程中出错数据元的检查和修正,对指导生产实践有一定的借鉴意义。 相似文献
9.
基于IGS的L2C信号跟踪站数据验证了具有L2C码的卫星的L2载波的信噪比高于没有L2C码的卫星的L2载波的信噪比,L2载波恢复的数据质量更好.针对不同的接收机,对比分析了C/A码和L2C码多路径效应及观测噪声水平,发现对TRIMBLE NETRS接收机,L2C码误差水平明显高于C/A码,与期望结果相反. 相似文献
10.
On the precision and accuracy of IGS orbits 总被引：10，自引：6，他引：4
In order to explore the precision and accuracy of International GNSS Service (IGS) orbits, we difference geocentric satellite positions midway between successive daily Final orbits for the period starting 5 November 2006, when the IGS switched its method of antenna calibration, through 31 December 2007. This yields a time series of orbit repeatabilities analogous to the classical geodetic test for position determinations. If we compare our average positional discontinuities to the official IGS accuracy codes, root-sum-squared (RSS) for each pair of days, we find the discontinuities are not well correlated with the predicted performance values. If instead the IGS weighted root-mean-square (WRMS) values from the Final combination long-arc analyses are taken as the measure of IGS accuracy, we find the position differences and long-arc values are correlated, but the long-arc values are exaggerated, particularly around eclipses, despite the fact that our day-boundary position differences apply to a single epoch each day and the long-arc analyses consider variations over a week. Our method is not well suited to probe the extent to which systematic effects dominate over random orbit errors, as indicated by satellite laser ranging residuals, but eclipsing satellites often display the most problematic behavior. A better metric than the current IGS orbit accuracy codes would probably be one based on the orbit discontinuities between successive days. 相似文献
11.
In this study, the effect of different sampling rates (i.e. observation recording interval) on the Precise Point Positioning (PPP) solutions in terms of accuracy was investigated. For this purpose, a field test was carried out in ?orum province, Turkey, on 11 September 2019. Within this context, a Geodetic Point (GP) was established and precisely coordinated. A static GNSS measurement was occupied on the GP for about 4-hour time at 0.10 second (s)/10 Hz measurement intervals with the Trimble R10 geodetic grade GNSS receiver. The original observation file was converted to RINEX format and then decimated into the different data sampling rates as 0.2 s, 0.5 s, 1 s, 5 s, 10 s, 30 s, 60 s, and 120 s. All these RINEX observation files were submitted to the Canadian Spatial Reference System-Precise Point Positioning (CSRS-PPP) online processing service the day after the data collection date by choosing both static and kinematic processing options. In this way, PPP-derived static coordinates, and the kinematic coordinates of each measurement epoch were calculated. The PPP-derived coordinates obtained from each decimated sampling intervals were compared to known coordinates of the GP for northing, easting, 2D position, and height components. According to the static and kinematic processing results, high data sampling rates did not change the PPP solutions in terms of accuracy when compared to the results obtained using lower sampling rates. The results of this study imply that it was not necessary to collect GNSS data with high-rate intervals for many surveying projects requiring cm-level accuracy. 相似文献
12.
Haitao Wang Hu Jiang Jikun Ou Baoqi Sun Shiming Zhong Min Song Aizhi Guo 《GPS Solutions》2018,22(4):124
The merged GPS navigation files from the International GNSS Service (IGS) data centers, i.e., the Crustal Dynamics Data Information System (CDDIS), the Bundesamt für Kartographie und Geodäsie (BKG), the Scripps Institution of Oceanography (SIO), and the Institut Geographique National (IGN) are occasionally contaminated by anomalies and inconsistent user range accuracy (URA). This contamination impairs the performance assessment of GPS service, especially the system integrity. We remerged these files starting Day of Year (DOY) 1, 2000 using all available navigation data files from IGS stations. To effectively get the upper bound URA, a frequency-dependent pattern recognition method was developed. In addition, a comprehensive comparison between the navigation data remerged by us and those provided by the four IGS data centers was performed. The compared results revealed that TGD and Issue of Data Clock (IODC) were the dominating anomalies in the merged navigation data from CDDIS and SIO for the first several years after 2000, and M0, Ω0, ω, and af0 were the dominant anomalies in the merged data from IGN. In addition to a number of missing records, many records with incorrect PRN (pseudo-random noise number), identifying a GPS satellite, were found in files from the IGS data centers. Although the number of anomalies in the merged files from CDDIS has continued to decrease in recent years, they have not disappeared and would affect system-level assessment and scientific applications to a certain extent. The results also revealed that our remerged files were more complete, clean, compact and consistent, making them more suitable for GPS system performance assessment and related research studies. Moreover, those data are now openly available. 相似文献
13.
14.
M_DCB: Matlab code for estimating GNSS satellite and receiver differential code biases 总被引：6，自引：4，他引：2
Global navigation satellite systems (GNSS) have been widely used to monitor variations in the earth’s ionosphere by estimating total electron content (TEC) using dual-frequency observations. Differential code biases (DCBs) are one of the important error sources in estimating precise TEC from GNSS data. The International GNSS Service (IGS) Analysis Centers have routinely provided DCB estimates for GNSS satellites and IGS ground receivers, but the DCBs for regional and local network receivers are not provided. Furthermore, the DCB values of GNSS satellites or receivers are assumed to be constant over 1?day or 1?month, which is not always the case. We describe Matlab code to estimate GNSS satellite and receiver DCBs for time intervals from hours to days; the software is called M_DCB. The DCBs of GNSS satellites and ground receivers are tested and evaluated using data from the IGS GNSS network. The estimates from M_DCB show good agreement with the IGS Analysis Centers with a mean difference of less than 0.7?ns and an RMS of less than 0.4?ns, even for a single station DCB estimate. 相似文献
15.
Different types of GPS clock and orbit data provided by the International GPS Service (IGS) have been used to assess the accuracy
of rapid orbit determination for satellites in low Earth orbit (LEO) using spaceborne GPS measurements. To avoid the need
for reference measurements from ground-based reference receivers, the analysis is based on an undifferenced processing of
GPS code and carrier-phase measurements. Special attention is therefore given to the quality of GPS clock data that directly
affects the resulting orbit determination accuracy. Interpolation of clock data from the available 15 min grid points is identified
as a limiting factor in the use of IGS ultra-rapid ephemerides. Despite this restriction, a 10-cm orbit determination accuracy
can be obtained with these products data as demonstrated for the GRACE-B spacecraft during selected data arcs between 2002
and 2004. This performance may be compared with a 5-cm orbit determination accuracy achievable with IGS rapid and final products
using 5 min clock samples. For improved accuracy, high-rate (30 s) clock solutions are recommended that are presently only
available from individual IGS centers. Likewise, a reduced latency and more frequent updates of IGS ultra-rapid ephemerides
are desirable to meet the requirements of upcoming satellite missions for near real-time and precise orbit determination. 相似文献
16.
针对传统方法存在的缺陷,研究了利用Kalman滤波技术进行大规模GNSS网参数（主要包括测站位置参数、卫星轨道参数及极移参数）估计的理论方法与关键技术,并利用40个全球均匀分布的IGS站多天的观测数据对理论成果进行了验证。结果表明,本文估计得到的测站位置参数与IGS结果各分量较差的RMS值分别为0.85、1.1、1.21 cm,得到的卫星轨道参数外推1 h后与IGS最终星历各分量较差的RMS值分别为9.8、8.6、7.2 cm,得到的极移参数与IERS结果的较差基本在1 mas之内;该方法具有较高的估值精度,可有效地用于GNSS网各类参数的估计。 相似文献
17.
Absolute Positioning with Single-Frequency GPS Receivers 总被引：11，自引：3，他引：11
Ola Øvstedal 《GPS Solutions》2002,5(4):33-44
The use of precise post-processed satellite orbits and satellite clock corrections in absolute positioning, using one GPS
receiver only, has proven to be an accurate alternative to the more commonly used differential techniques for many applications
in georeferencing.
The absolute approach is capable of centimeter accuracy when using state-of-the-art, dual-frequency GPS receivers. When using
observations from single-frequency receivers, however, the accuracy, especially in height, decreases. The obvious reason for
this degradation in accuracy is the effect of unmodeled ionospheric delay.
This paper discusses the availability of some empirical ionospheric models that are publicly available and quantifies their
usefulness for absolute positioning using single-frequency GPS receivers. The Global Ionospheric Model supplied by International
GPS Service (IGS) is the most accurate one and is recommended for absolute positioning using single-frequency GPS receivers.
Using high-quality single-frequency observations, a horizontal epoch-to-epoch accuracy of better than 1 m and a vertical accuracy
of approximately 1 m is demonstrated. ? 2002 Wiley Periodicals, Inc. 相似文献
18.
The anomaly phenomenon of broadcast ionospheric model coefficients of the Global Positioning System (GPS) is revealed after analyzing the navigation file data collected from all the IGS (International GNSS Service) stations worldwide over a 22-year period (1992–2013). GPS broadcast ionospheric coefficients widely used by many single-frequency users to correct the ionosphere errors for numerous GPS applications are usually believed to have only one set/version per day. However, it is found that GPS receivers from the IGS network can report as many as eight sets/versions of ionospheric coefficients in a day. In order to investigate the possible factors for such an anomalous phenomenon, the relationship between the number of coefficient sets and solar cycle, the receiver geographic locations, and receiver types/models are analyzed in detail. The results indicate that most of the coefficients show an annual variation. During the active solar cycle period from mid-1999 to mid-2001, all of the coefficients extracted from IGS navigation files behaved anomalously. Our analysis shows that the anomaly is also associated with GPS receiver types/models. Some types/models of GPS receivers report one set/version of ionospheric coefficients daily, while others report multiple sets. Our analysis also suggests that the ionospheric coefficient anomaly is not necessarily related to ionospheric scintillations. No correlation between the anomaly and geographic location of GPS receivers has been found in the analysis. Using the ionospheric coefficient data collected from 1998 to 2013, the impact of ionospheric coefficient anomaly on vertical total electron content (VTEC) calculation using the Klobuchar model has been evaluated with respect to the Global Ionospheric Maps generated by the Center for Orbit Determination in Europe. With different sets of coefficients recorded on the same day, the resulting VTEC values are dramatically different. For instance on June 1, 2000, the largest VTEC at one of our test stations can be as large as 153.3 TECu (total electron content unit) using one set of coefficients, which is 16.36 times larger than the smallest VTEC of 9.37 TECu computed from using another set of coefficients. 相似文献
19.
Real-time clock jump compensation for precise point positioning 总被引：1，自引：1，他引：0
20.
The mathematical interaction between the simultaneous rotation of both a coordinate frame and a set of physical vectors in that frame is covered and theoretically and empirically explained. A practical example related to the secular motion of the pole determined using recent GPS results is addressed. A least-squares adjustment is introduced to determine a possible displacement of the geodetic north pole of the frame caused by plausible changes in the coordinates of the observing stations defining the frame due to the rotation of the plates on which these stations are located. Two examples of GPS networks are investigated both referred to the latest definition of the IGS08 geodetic frame. The positioning and velocities of the points were exclusively obtained using GPS data as published by the International GNSS Service (IGS). The first case comprises the complete GPS/IGS network of global stations; the second one assumes the closest GPS/IGS stations to the now discontinued International Latitude Service network. The results of this exercise hints at the possibility that the secular global rotation of the frame caused by plate rotations should be accounted for in order to rigorously determine the true absolute velocities referred to the IGS frame before the actual velocities of the rotation of the plates using GPS observations are published. 相似文献