GPS Pathfinder Office Software and the GPS Analyst Extension: Creating User-defined Base Providers

Transcription

1 26 January 2010 GPS Pathfinder Office Software and the GPS Analyst Extension: Creating User-defined Base Providers This support note provides instructions for setting up a user-defined base provider in the GPS Pathfinder Office software or the GPS Analyst extension for the ESRI ArcGIS Desktop software. A user-defined base provider can be set up to represent a base station that makes its data available over the Internet, on a local network, or offline (for example, a provider that sends base data to you by mail). Contents Why create user-defined base providers?, page 2 Setting up a base provider, page 2 Required fields in the Base Provider Properties dialog, page 3 Accessing files on your own computer or network, page 5 Using variables, page 6 Common address formats, page 7 Distributing a list of user-defined base providers, page 9 Troubleshooting, page 10 Appendix List of variables, page 11 This document is for informational purposes only and is not a legally binding agreement or offer. Trimble makes no warranties and assumes no obligations or liabilities hereunder. Trimble Navigation Limited, 7401 Church Ranch Blvd, Westminster, CO 80021, USA 2010, Trimble Navigation Limited. All rights reserved. Trimble, the Globe & Triangle logo, and GPS Pathfinder are trademarks of Trimble Navigation Limited, registered in the United States Patent and Trademark Office and in other countries. GPS Analyst and H-Star are trademarks of Trimble Navigation Limited. All other trademarks are the property of their respective owners. Page 1

2 Why create user-defined base providers? Both the GPS Pathfinder Office software and the GPS Analyst extension allow you to select base data by browsing for specific files, or by specifying a folder to search. A user-defined base provider has the following advantages over these methods: Save time You do not need to browse a website or network drive for the files you require. Once defined, the base provider can be re-used each time you postprocess data. The tasks of selecting and downloading the correct files for the required time span are done automatically. Perform multi-base H-Star processing H-Star technology postprocessing may use data from more than one base stations to improve the accuracy of corrected GPS positions. In order to postprocess against data from multiple base stations, each base station needs to have a corresponding base provider defined. You cannot currently use a folder search or browsing in H-Star processing. Define an accurate reference position The accuracy of a base station s reference position affects the accuracy of the corrected GPS positions. By default, if you use a folder search or browse for base data, the reference position is taken from the base file header. Often this reference position is inaccurate, or is not defined in terms of the reference frame or datum you require. When you define a base provider, you can specify an accurate reference position that will be used in postprocessing instead of the position defined in the base file header. Setting up a base provider To set up a new base provider in the GPS Pathfinder Office software or GPS Analyst extension: 1. Start the Differential Correction wizard. 2. Choose any SSF file or GPS session to correct and then click Next. 3. In the second step of the wizard, select one of the Standard processing options and then click Next. 4. Click Next again. Page 2

3 5. Click the Select button beside the Base Provider Search option. The Select Base Provider dialog appears: 6. Click New to set up a new base provider, or highlight an existing base provider and then click Copy to create a new base provider based on the selected existing provider properties. 7. Fill in the required fields in each tab of the Base Provider Properties dialog. See the following section for more detail on each required field. You have now set up a user-defined base provider. Tip: The GPS Analyst extension includes a Manage Base Provider tool that you can add to the GPS Analyst toolbar. You can use this tool to display the Select Base Provider dialog without going through steps 1 to 5 above. For more information, see the topic Customizing the GPS Analyst toolbar, in the GPS Analyst help. Required fields in the Base Provider Properties dialog General tab The General tab of the Base Provider Properties dialog provides general information about the base station provider. You must fill in the Organization field when you add a new base provider. The information in this field is used to identify the base provider in the Differential Correction wizard. All other fields in this tab are optional. Base Station tab Use the Base Station tab to specify information about the type of base station and the reference position of the base station. You must fill in the Latitude, Longitude, and Altitude fields with an accurate reference position. All other fields in this tab are optional. The more accurate the reference position, the more accurate your corrected rover positions will be. Page 3

4 System-defined base stations specify their reference position in terms of the WGS-84 datum (or the equivalent ITRF reference frame). You can specify the reference position in terms of any reference frame (for example the NAD 83 datum), but remember that the corrected GPS data will also be in terms of that reference frame. If you are doing H-Star processing, it is extremely important that all of the base stations you select for processing use the same reference frame. If their reference positions are in terms of mixed reference frames (for example, if one station s position is in terms of WGS-84 but the others are in terms of NAD 83), you will introduce datum shift errors that cannot be removed. For more information on reference frames and differential correction, refer to the White Paper titled H-Star Technology Explained (available at and the Support Note titled Resolving the NAD 83 Datum Issue ( Internet Server tab The Internet Server tab is where you specify where the base data is stored and how it is named. Base File Address Format This field specifies where the base files reside, and the filename format of the base files. The files may be stored on an ftp site, a web site, an igate server, on your local network, or on your local computer. This field uses variables to represent parts of the path and filename that vary depending on the base file. See the Using variables section below for more information. Time Format Select which time format the base files use. Options are local time or GPS time. If files are named using the local time, you must set your computer s time zone to the same time zone in order to successfully download files. Time Span Enter a number or use the up/down buttons to specify the time span in hours of the base files. Normally base data is stored in daily (24-hour) or hourly (1-hour) files. Station ID Enter a code that identifies this base station. You only need to enter a station ID if it is used in the base data s path or filename. The station ID is represented by the %CCCC% variable in the download string. RINEX Format Select this check box if the base files are in RINEX format (.obs and.nav files). Nav File Address Format If you select the RINEX Format check box, but leave this field blank, the Differential Correction wizard will try to locate the.nav files in the same folder as the.obs files, using the base file address format as a template. For example, if.obs files are named %yymmddhh.%yy%o, then the Differential Correction wizard will look for %yymmddhh.%yy%n (GPS) and %yymmddhh.%yy%g (GLONASS) files. Page 4

5 If the nav files are not in this expected location (for example, they are zipped in the same file as the obs files, or are in another folder) you must specify the address format for downloading the RINEX navigation files. If the.obs files and.nav files are in the same compressed file, then you must enter the same download string in both Address Format fields. Security tab If you have to enter a username and password (in addition to logging in to Windows) to access the base data, select the Restricted Access option in this tab. If you can access the data freely, select the Public Access option. If you leave the User Name and Password fields blank, you must enter them each time you download data. If you are setting up a base provider definition that will be distributed to a number of users, each with their own base data login, leave these fields blank so that each user will be required to enter their own login details. Accessing files on your own computer or network Your own organization s base data is probably stored on a local or network drive rather than on an ftp site or website. You can set up a base provider entry to access these files, so that your local data appears in the list of base providers just like nearby Internet providers. If there is a drive letter permanently mapped to this location, you can use the drive letter in the address format. Examples (1) to (3) all refer to the same network location the folder called RINEX on drive S: S:\RINEX\ (1) file://s:\rinex\ (2) file:///s:/rinex/ (3) If the location is not on a local or mapped drive, use the file:// protocol or the Universal Naming Convention (UNC) path to refer to the network location. The following examples refer to the same location: the share called RINEX on the computer called fileserver1: file://fileserver1/rinex/ (4) \\fileserver1\rinex\ (5) Notice the direction and number of slashes in each example. The file:// protocol (4) uses forward slashes, but the UNC path (5) uses backslashes. It is very important to get these right. Note: The file:// protocol does not support long names for files or folders, or empty spaces in the folder path. Note: The postprocessing software cannot download base files that include empty spaces in the filename. This restriction applies whether you use the drive letter, UNC path, or file:// protocol to access the files. Page 5

6 Using variables The address format fields for a base provider specify where the base data is stored. Variables are used to represent parts of the URL that vary depending on the day, date, time, or station ID. A variable is an alphanumeric code that begins and ends with the % character. See the Appendix for a list of the variables that can be used when defining address format strings. To work out what the address format should be, copy the full path and filename for a particular file into the Base File Address Format field. Then work through the string from left to right, using variables to replace any part of the string that changes. Example In the example above, the base station names files by station ID (ABCD) and date. Files are stored in folders arranged by year and then by month. The full path and filename for the first file is shown below: S:\RINEX\2006\January\ABCD\ABCD zip Working from left to right, the table below shows the text in the path that varies, and the variables that are required to replace this text: String Varies? Represented in download string as S: No S: RINEX No RINEX 2006 Yes %yyyy% January Yes %mmmm% ABCD Yes %CCCC% Yes %yymmdd%.zip No.zip The resulting address format is: S:\RINEX\%yyyy%\%mmmm%\%CCCC%\%CCCC%%yymmdd%.zip Page 6

7 Note: Previously, the %CCCC% mask was used to substitute the 4-character CORS station identifier into the Base File URL. The functionality of this mask has been extended to allow use by non-cors base stations, increasing the character limit to 15, and to enable different combinations of upper- and lowercase substitutions, regardless of case of specified identifier, as below. Download string Varies? Base station identifier %CCCC% Yes Upper-case base station identifier ABCD %cccc% Yes Lower-case base station identifier abcd %Cccc% Yes Mixed-case base station identifier, starting with upper case letter Abcd %CcCc% Yes No automatic case shifting is employed. This is useful for names, such as LeHavre. Using the BASE FILE FORMAT entries as further examples, on 31 December 2009, with base station identifier "Westminster": The full path and filename is: ftp://ftp.trimble.com/public/gps_data/rinex24/2009/365/westminster/westminster3650.zip The resulting address format is: ftp://ftp.trimble.com/public/gps_data/rinex24/%yyyy%/%ddddd%/%cccc%/%cccc%%ddd DD%0.zip The full path and filename is: ftp://ftp.trimble.com/public/gps_data/rinex24/2009/dec31/westminster/westminster3650.zip The resulting address format is ftp://ftp.trimble.com/public/gps_data/rinex24/%yyyy%/%mmm%%dd%/%cccc%/%cccc%%d DDDD%0.zip Common address formats This section lists some common address formats. GPSBase, GPSNet, and RTKNet The RINEX Storage module in these base station applications lets you define which RINEX files you want to store, and how to structure and name the storage folder and files. The table below shows how these options are represented using download string variables. Format Download string Example Enhanced Month Month.%Mmm% Month.Dec Enhanced Day Day.%dd% Day.31 CORS rinex/%yyyy%/%ddddd%/%cccc% rinex/2006/365/abcd Add point name %CCCC% ABCD Use CORS file naming %cccc%%ddddd%%hrasletter%.%yy%o abcd365b.06o Use time for file naming %yymmddhh%.%yy%o o Page 7

8 If the Add point name to folder structure check box is selected, then the point name defined in the Local point number field of the Next File step of the wizard is used to name the folder at the lowest level in the structure. The variable %cccc% can be used in the download string to represent the point name. After defining the storage structure in a RINEX Storage module, you can add a Compress module to copy the files into a compressed file. The compression options that are supported by the Differential Correction wizard are.zip,.exe, and.z. Examples Format Plain, Add point number, Use CORS file naming Enhanced day, Use time for file naming, zip compression CORS Download string C:\%cccc%\%cccc%%ddddd%%hrasletter%.%yy%o C:\RefData.%YY%\Month.%MMM%\Day.%DD%\%YYMMDDHH %.%YY%o.zip C:\rinex\%yyyy%\%ddddd%\%cccc%\%CCCC%%ddddd%%hraslett er%.%yy%o CORS and COOP CORS stations The National Geodetic Survey (NGS) has guidelines for naming and organizing RINEX base files. The strings below represent the most common address formats for CORS data: Format Hourly files, uncompressed Hourly files, zipped Daily files, zipped Download string ftp://base_folder/rinex/%yyyy%/%dddd%/%cccc%/%cccc %%DDDDD%%hrasletter%.%YY%o ftp://base_folder/rinex/%yyyy%/%dddd%/% CCCC%/%CCCC %%DDDDD%%hrasletter%.%YY%o.zip ftp://base_folder/rinex/%yyyy%/%ddddd%/% CCCC%/%CCCC %%DDDDD%0.zip Page 8

9 Distributing a list of user-defined base providers User-defined base providers are stored separately from system-defined providers, in an XML file. To distribute a list of user-defined base providers, simply copy this XML to each computer where it is required. For the GPS Pathfinder Office software, user-defined base providers are stored in C:\Program Files\Common Files\Trimble\Config\user_list.xml. For the GPS Analyst extension, user-defined base providers are stored in C:\Documents and Settings\<username>\Application Data\Trimble\GPS Analyst\user_list.xml, where <username> is the name that you are logged in as. If there is an existing user_list.xml file on the destination computer, replacing it will delete any userdefined base providers already set up on that computer. If you want to merge the two, copy and paste everything in the file between (but not including) the <root> and </root> tags. Page 9

10 Troubleshooting Case sensitive text The variables that represent alphabetic data (for example, the name of the month) are case-sensitive. For example: %MMMM% %Mmmm% %mmmm% JANUARY January January For most servers, it does not matter whether you use capital letters or lower case in the variable. To these servers, the folder name January is the same as the folder name january. However, some ftp servers are case-sensitive. If you do not specify the correct case for the variable, the download will fail. The variables that represent the Station ID (ABCD) can be case sensitive as well. For example: %CCCC% %cccc% %Cccc% ABCD abcd Abcd Note: When Trimble extended the Station ID mask definition to allow case sensitive IDs, Trimble undertook to change the base file format definitions in your files. As some servers are password protected, Trimble recommends that you take this opportunity to check your base file format definitions and inform Trimble of any changes that are required. You may also like to use this opportunity to inform Trimble of new base stations that you would like to add to the existing list, or obsolete stations that require removal. Please provide additions and updates to your base stations by using the interactive web form: Missing files If a download fails, check that the files that the Differential Correction wizard is looking for exist. The correction summary shows the path or URL that the Differential Correction wizard attempted to download from. Verify that this path and filename exist. Local time vs GPS time If the base files are named using the local time format, you must set your computer s time zone to match. If they do not match, files will be downloaded successfully but they will be for the wrong time span. Spaces in filename or path Make sure that the base file naming convention you choose does not include spaces in the filename. The Differential Correction wizard cannot download files with spaces in the filenames. Also, if you are using the file:// protocol to access files on your local network, you cannot access paths that include long names or spaces in folder names. Use the UNC path or a mapped drive letter instead of the file:// protocol. Page 10

11 Appendix List of variables The table below lists all of the variables that you can use in download strings. Variable Description Example %CCCC% 4-character station ID ABCD %ll% File duration (1,, 24) 24 %d% Day of month 6 %dd% Day of month with a leading zero 06 %ddd% Day of week short form Wed %dddd% Day of week long form Wednesday %ddddd% Day of year with leading zeros 365 (31 December, 365th day of the year) %m% Month number 6 (June) %mm% Month number with a leading zero 06 (June) %mmm% Month name short form Oct %mmmm% Month name long form October %y% Last digit of year 6 (2006) %yy% Last two digits of year 06 (2006) %yyyy% Four digit year 2006 %h% Hour of day (in 24 hour format) 14 (2 p.m.) %hh% Hour of day (in 24 hour format) with a leading zero 09 (9 a.m.) %hrasletter% Hour of day, where the hour is interpreted as a letter h (8 a.m.) %ww% Week number with a leading zero 25 (25th week of the year) %ymmddhh% Year, month, day, and hour with leading zero on month, day, and hour (10 a.m. 15 January 2006) %yymmddhh% Year, month, day, and hour with leading zero on all values (10 a.m. 15 January 2006) %mmyy% Month and day with leading zeroes 0115 (January 2006) %ymmdd% Year, month, and day with leading zero on month (15 January 2006) and day %yymmdd% Year, month, and day with leading zero on all (15 January 2006) values %mmddhh% Month, day, and hour with leading zero on all values (10 a.m. 15 January) Page 11