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1.
Jan Kouba 《GPS Solutions》2002,5(3):88-90
The GPS Toolbox is dedicated to highlighting algorithms and source code utilized by GPS engineers and scientists. If you have
an interesting subroutine or program you would like to share with our readers, please pass it along so that we might continue
to bring you this column; e-mail it to us at gps-toolbox@ngs.noaa.gov. To comment on any of the source code discussed here,
or to leave a request for a piece of source code you may be looking for, visit our web site at http:/www.ngs.noaa.gov/gps-toolbox.
This column is edited by Stephen Hilla, National Geodetic Survey, NOAA, Silver Spring, Maryland, and Mike Craymer, Geodetic
Survey Division, Natural Resources Canada, Ottawa, Ontario, Canada. ? 2002 Wiley Periodicals, Inc. 相似文献
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C++ and Java code for recursion formulas in mathematical geodesy 总被引：2，自引：0，他引：2
Klaus Hehl 《GPS Solutions》2005,9(1):51-58
4.
Several hybrid neutral atmosphere delay models have been developed at the University of New Brunswick. In this paper we are
presenting UNB3m_pack, a package with subroutines in FORTRAN and corresponding functions in MatLab which provides neutral
atmospheric information estimated using the UNB3m model. The main goal of UNB3m is to provide reliable predicted neutral atmosphere
delays for users of global navigation satellite systems (GNSS) and other transatmospheric radiometric techniques. Slant neutral
atmosphere delays are the main output of the package, however, it can be used to estimate zenith delays, Niell mapping functions
values, delay rates, mapping function rates, station pressure, temperature, relative humidity and the mean temperature of
water vapor in the atmospheric column. The subroutines work using day of year, latitude, height and elevation angle as input
values. The files of the package have a commented section at the beginning, explaining how the subroutines work and what the
input and output parameters are. The subroutines are self-contained, i.e., they do not need any auxiliary files. The user
has simply to add to his/her software one or more of the available files and call them in the appropriate way.
The GPS Tool Box is a column dedicated to highlighting algorithms and source code utilized by GPS engineers and scientists.
If you have an interesting program or software package you would like to share with our readers, please pass it along; e-mail
it to us at gps-toolbox@ngs.noaa.gov. To comment on any of the source code discussed here, or to download source code, visit
our website at . This column is edited by Stephen Hilla, National Geodetic Survey, NOAA, Silver Spring, Maryland, and Mike Craymer, Geodetic
Survey Division, Natural Resources Canada, Ottawa, Ontario, Canada. 相似文献
5.
MATLAB Tools for viewing GPS velocities and time series 总被引：3，自引：2，他引：1
Over the past decade, many Global Positioning System (GPS) networks have been installed to monitor tectonic motions around the world. Some of these networks contain hundreds of sites spread across active tectonic margins where the differences in velocities across the network can be 50–100 mm/year. For networks that have been running for a number of years, the uncertainty in the velocity estimates can be less than 1 mm/year. In some cases the vertical motions can also be significant and of importance. Often, the time series of the motions of the GPS sites show complex non-linear behavior, and in all cases the statistical model of the time series is more complex than simple white noise. In this article, we describe a set of Matlab tools developed for use with the GAMIT/GLOBK GPS data analysis system (King 2002; King and Herring 2002) that allow interactive viewing and manipulation of GPS velocities and time series with a Matlab-based graphical user interface (GUI). The formats of the data files used by the tools are specific to GAMIT/GLOBK, but they are simple ASCII files that can be generated from other file formats. The tools are referred to as GGMatlab.The GPS Toolbox is a column dedicated to highlighting algorithms and source code utilized by GPS Engineers and scientists. If you have an interesting program or software package you would like to share with our readers, please pass it along; e-mail it to us at gps-toolbox@ngs.noaa.gov/. To comment on any of the source code discussed here, or to download source code, visit our website at . This column is edited by Stephen Hilla, National Geodetic Survey, NOAA, Silver Spring, Maryland, and Mike Craymer, Geodetic Survey Division, Natural Resources Canada, Ottawa, Ontario, Canada. For the sidebar, see the Volume 6, Number 4, 2003 issue of the GPS Toolbox column. 相似文献
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The Scripps Orbit and Permanent Array Center (SOPAC) has completed development for the UNAVCO community of first-generation GPS Seamless Archive (GSAC) software. The GSAC is a virtual archive composed of an assembly of agencies and investigators exchanging information about their respective GPS-related data holdings in a well defined, cohesive manner. The superset of this published information is collected and ingested into centralized databases administered currently by two data brokers (Retailers), who make the data available to the public in a seamless manner. There are three user interfaces available: the interactive GSAC Wizard, a command-line Unix-style executable called gsac-client, and a front door HTTP service called the GSAC Retailer Service Interface. Each user interface provides access to the data collections of 6 different GPS archives (GSAC Wholesalers) in North America. Together these archives have published more than 2 million GPS data files pertaining to over 10,000 different geodetic monuments. These datasets are composed in large part of data collected by US scientists and their collaborators over the period 1986 to the present in Western North America and other tectonically active regions around the globe, as well as the holdings of two IGS global data centers. In this article, we describe how the three GSAC user interfaces provide the community a powerful set of tools for seamlessly mining information and collecting data files from a distributed network of GPS archives.The GPS Toolbox is a column dedicated to highlighting algorithms and source code utilized by GPS Engineers and scientists. If you have an interesting program or software package you would like to share with our readers, please pass it along; e-mail it to us at gps-toolbox@ngs.noaa.gov. To comment on any of the source code discussed here, or to download source code, visit our website at . This column is edited by Stephen Hilla, National Geodetic Survey, NOAA, Silver Spring, Maryland, and Mike Craymer, Geodetic Survey Division, Natural Resources Canada, Ottawa, Ontario, Canada. 相似文献
8.
Doug Hunt 《GPS Solutions》2000,4(1):74-76
The GPS Toolbox is dedicated to highlighting algorithms utilized by GPS engineers and scientists. If you have an interesting
algorithm you would like to share with our readers or if you have a topic you would like to see covered in a future column,
contact us at gps-toolbox@ngs.noaa.gov. To comment on the algorithms presented here, or to leave a request for an algorithm
you may be looking for, visit our Web site (http://www.ngs.noaa.gov/gps-toolbox). ? 2000 John Wiley & Sons, Inc. 相似文献
9.
GNSS data management and processing with the GPSTk 总被引：2，自引：0，他引：2
Dagoberto Salazar Manuel Hernandez-Pajares Jose M. Juan Jaume Sanz 《GPS Solutions》2010,14(3):293-299
We organize complex problems in simple ways using a GNSS data management strategy based on “GNSS Data Structures” (GDS), coupled
with the open source “GPS Toolkit” (GPSTk) suite. The code resulting from using the GDS and their associated “processing paradigm”
is remarkably compact and easy to follow, yielding better code maintainability. Furthermore, the data abstraction allows flexible
handling of concepts beyond mere data encapsulation, including programmable general solvers. An existing GPSTk class can be
modified to achieve the goal. We briefly describe the “GDS paradigm” and show how the different GNSS data processing “objects”
may be combined in a flexible way to develop data processing strategies such as Precise Point Positioning (PPP) and network-based
PPP that computes satellite clock offsets on-the-fly. 相似文献
10.
《测量评论》2013,45(74):146-155
AbstractShortly after the inception of the Geodetic Survey of Canada in 1905, reconnaissance for primary triangulation was commenced in the Ottawa-Montreal area. About the same time, precise levelliilg operations were begun from a bench mark already established by the United States Coast and Geodetic Survey near the International border at Rouses Point in Quebec. 相似文献
11.
A new adjustment of the geodetic control networks in North America has been completed, resulting in a new continental datum—the
North American Datum of 1983 (NAD 83).
The establishment ofNAD 83 was the result of an international project involving the National Geodetic Survey of the United States, the Geodetic Survey
of Canada, and the Danish Geodetic Institute (responsible for surveying in Greenland). The geodetic data in Mexico and Central
America were collected by the Inter American Geodetic Survey and validated by the Defense Mapping Agency Hydrographic/Topographic
Center.
The fundamental task ofNAD 83 was a simultaneous least squares adjustment involving 266,436 stations in the United States, Canada, Mexico, and Central
America. The networks in Greenland, Hawaii, and the Caribbean islands were connected to the datum through Doppler satellite
and Very Long Baseline Interferometry (VLBI) observations.
The computations were performed with respect to the ellipsoid of the Geodetic Reference System of 1980. The ellipsoid is positioned
in such a way as to be geocentric, and its axes are oriented by the Bureau International de l'Heure Terrestrial System of
1984.
The mathematical model for theNAD readjustment was the height-controlled three-dimensional system. The least squares adjustment involved 1,785,772 observations
and 928,735 unknowns. The formation and solution of the normal equations were carried out according to the Helmert block method.
[Authors' note:This article is a condensation of the final report of the NAD 83 project. The full report (Schwarz,1989) contains a more complete discussion of all the topics.] 相似文献
12.
非组合精密单点定位算法精密授时的可行性研究 总被引：4，自引：1，他引：3
利用基于GPS双频原始观测数据的非组合精密单点定位(PPP)算法进行精密授时,给出了其数学模型与数据预处理策略。实验结果表明,非组合PPP算法可以有效避免传统PPP算法由于观测值组合过程中观测噪声及多路径效应误差被放大而造成的对接收机钟差解算的不利影响,实现亚纳秒级(0.3 ns)的钟差解算精度;同等条件下,非组合PPP算法授时精度优于传统PPP算法,可以用于精密授时解算。 相似文献
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Software receivers have had a discernable impact on the GNSS research community. Often such receivers are implemented in a compiled programming language, such as C or C++. A software receiver must emulate the digital signal processing (DSP) algorithms executed on dedicated hardware in a traditional receiver. The DSP algorithms, most notably correlation, have a high computational cost; this burden precludes many software receivers from running in real time. However, the computational cost can be lessened by utilizing single instruction multiple data (SIMD) operations found on modern ×86 processors. The following demonstrates how C/C++ compatible code can be written to directly utilize the SIMD instructions. First, an analysis is carried out to demonstrate why real time operation is not possible when using traditional C/C++ code is carried out. Secondly a tutorial outlines how to write and insert ×86 assembly, with SIMD operations, into C/C++ code. Performance gains achieved via SIMD operations are then demonstrated, and pseudo code outlines how SIMD operations can be employed to perform correlation. Finally, a C/C++ compatible SIMD enabled arithmetic library is added to the GPS Toolbox for use in software receivers. 相似文献
15.
GPS Antenna Calibration at the National Geodetic Survey 总被引：15，自引：2，他引：13
Gerald L. Mader 《GPS Solutions》1999,3(1):50-58
The precise point whose position is being measured when a GPS baseline is determined is generally assumed to be the phase
center of the GPS antenna. However, the phase center of a GPS antenna is neither a physical point nor a stable point. For
any given GPS antenna, the phase center will change with the changing direction of the signal from a satellite. Ideally, most
of this phase center variation depends on satellite elevation. Azimuthal effects are only introduced by the local environment
around each individual antenna site. These phase center variations affect the antenna offsets that are needed to connect GPS
measurements to physical monuments. Ignoring these phase center variations can lead to serious (up to 10 cm) vertical errors.
This article will describe the procedure by which the National Geodetic Survey is calibrating GPS antennas and how this information
may be obtained and used to avoid problems from these antenna variations. ? 1999 John Wiley & Sons, Inc. 相似文献
16.
全球导航卫星系统的新进展 总被引：12，自引：1，他引：11
本文综合介绍了于 2 0 0 4年 9月 2 1日至 2 4日在美国加州举行的“全球导航卫星系统” 2 0 0 4年年会(GNSS2 0 0 4 )会议的主要议题 ,并对其中我们可能关切的方面进行了重点介绍。①美国的GPS连续运行站网(CORS)。CORS由美国大地测量局 (NGS)主持运行。用户可以通过NGS网络 ,获得用户的GPS待定点相邻的CORS站 (三个以上 )的GPS相应载波相位和码距 ,以支持用户的GPS准实时或后处理定位。NGS也可以为用户通过网络提供GPS定位计算服务 ,这一服务可以在用户提供待定点的观测资料后的几个小时内完成 ,称为NGS的在线GPS定位服务。CORS目前在美国已有 5 0 0余个站。②GPS系统的进展。GPSⅡR型卫星从体形和功能方面都比较优秀 ,使GPS卫星在轨的位置误差显著降低 ,测距精度提高近一倍 ,目前GPSⅡR型卫星截止至 2 0 0 4年 1月 1日时有 9颗在轨。③利用L1 ,L2频道的GPS空基增强系统 (WAAS)。在美国大部分地区WAAS系统的水平精度可达 1～ 2m ,垂直精度可达 2～ 3m。④GPS信号的重构。美国已发展了一种高度逼真的和适应各种情况的虚拟GPS信号系统 ,这种虚拟发射装置可以是陆基的 ,空基的 ,或者星基的。GPS接收机可以利用这一虚拟的GPS信号进行精密定位。⑤Galileo卫星导航系统运行的准备工作。欧洲空间局已经重新和? 相似文献
17.
High-performance GPS RTK software has been developed within the Geodetic Research Laboratory (GRL) at the University of New Brunswick (UNB). This software was initially designed for gantry crane auto-steering. Due to limitations with classical geodetic deformation monitoring techniques, the Canadian Centre for Geodetic Engineering (CCGE) at UNB has decided to augment its fully automated deformation monitoring system with GPS. As a result, the GRL and CCGE have combined efforts to achieve the required precision. As a first step, tests of the GPS real-time kinematic (RTK) software have been carried out at Highland Valley Copper Mine in British Columbia, Canada. An open-pit mine environment places certain constraints on the achievable accuracies attainable with GPS. Consequently, the software has been modified to meet the needs of this particular project and data have been post-processed for analysis. This paper describes the approach taken at UNB to address high precision requirements in a constrained signal availability environment. Technical and scientific aspects of the UNB software, especially in handling two predominant errors (residual tropospheric zenith delay and multipath) at the mine, are discussed. Results of tests that have been carried out at the mine are presented. 相似文献
18.
We processed 30 consecutive days of Global Positioning System (GPS) data using the On-line Positioning Users Service (OPUS)
provided by the National Geodetic Survey (NGS) to determine how the accuracy of derived three-dimensional positional coordinates
depends on the length of the observing session T, for T ranging from 1 h to 4 h. We selected five Continuously Operating Reference Stations (CORS), distributed widely across the
USA, and processed the GPS data for each with corresponding data from three of its nearby CORS. Our results support the current
OPUS policy that recommends using a minimum of 2 h of static GPS data. In particular, 2 h of data yielded a root mean square
error of 0.8, 2.1, and 3.4 cm in the north, east, and up components of the derived positional coordinates, respectively. Results
drastically improve for solutions containing 3 h or more of GPS data. 相似文献
19.
The activities of the Ionosphere Working Group of the International GPS Service (IGS) 总被引：5，自引：2，他引：3
This article is based on a position paper presented at the IGS Network, Data and Analysis Center Workshop 2002 in Ottawa,
Canada, 8–11 April 2002, and introduces the IGS Ionosphere Working Group (Iono_WG). Detailed information about the IGS in
general can be found on the IGS Central Bureau Web page: http://igscb.jpl.nasa.gov. The Iono_WG commenced working in June
1998. The working group's main activity currently is the routine production of ionosphere Total Electron Content (TEC) maps
with a 2-h time resolution and daily sets of GPS satellite and receiver hardware differential code bias (DCB) values. The
TEC maps and DCB sets are derived from GPS dual-frequency tracking data recorded with the global IGS tracking network.
In the medium- and long-term, the working group intends to refine algorithms for the mapping of ionospheric parameters from
GPS measurements and to realize near–real–time availability of IGS ionosphere products. The paper will give an overview of
the Iono_WG activities that include a summary of activities since its establishment, achievements and future plans.
Electronic Publication 相似文献