RT Post-process User Manual
Contents
1. POS and OTA Optech ASCII The Select Fields page is shown in Figure 12 Revision 111102 EI Figure 12 Select Fields page T Set Fields RT2000 Choose the fields you want in output file Inertial and GPS Measurement System Date TimeOfDay TimeFromStart Check the items which Pos Latitude Longitude Altitude PosLocal North East you would like to output PosLocal 4Y Step 6 of 9 v DistanceFromStart A IEF M Vel North East Down v Vel Forward Lateral Select Raw Data File J VelLocal KY Working Directory V Speed Base Station v Accel KY Z Process Page v Accel Forward Lateral Down v Angle Heading Pitch Roll v AngleFromSurf Heading Pitch Roll Output Config Angle IpsOmega IpsPhi IpsKappa _ Qutput format Y Output File al AnaleSlin AnaleTrack Mirvahira Finish Page qj u Confidently Select All Clear All Accurately E SS Tih Tb eh ek SS To select the output format for the file use the Output format dropdown list on the right hand side of the page under the hint box For the CSV export there are lots of fields and they can be enabled or disabled as required For the POS and OTA files the fields can be selected but the format is only correct when all the fields are used Output Configuration page The Output Configuration page can be used to select some of the units used and to set some conditions for the outputs for e2. 1 25114334 deg Alt 133 591 m OK Cancel The base station location entered must be the location of the antenna s phase centre RT Post process does not use an antenna model and an antenna reference point The co ordinates of the antenna s phase centre can be entered in decimal degrees or in degrees minutes and seconds Use the tabs to swap from one format to the other The base station name can be changed at the top of the dialog box If the same name is used then the old location will be overwritten Reprocessing GPS data outside of RT Post process Although GrafNav can be used with RT Post process there are times when it is better to process the data in GrafNav itself rather than use the standard configuration that RT Post process uses For example if multiple base stations are available or if a special processing option is needed With the Inertial different post processing software will be needed For example Topcon provides Topcon Tools for reprocessing the data from Topcon receivers It is possible to save the Topcon data in the Inertial export it from RT Post process then import the processed data after it has been processed using Topcon Tools This applies to other GPS receivers too It is possible to keep the external GPS receiver completely separate from the Inertial and then only combine the external receiver with the Inertial after it has been post processed For example log the raw data required for
3. the acceleration due to gravity changes depending on where you are on the earth s surface Although the RT uses a gravity model in its calculations this is not used in RT Post process Time Reference Units This option can be used to set the units for time in the output files The NCOM file always writes files using the GPS time system RT Post process can convert this to UTC or GMT time by adding the UTC offset to time RT Post process can also convert the time to the local time used on the PC by using the time zone selected in the PC For invalid measurements This option can be used to decide what to write when there are invalid measurements NCOM includes a method of defining some measurements as not valid and this can be written into CSV files by using a blank field However some software does not accept blank fields RT Post process can fill in blank fields with zeros or it can hold the last known value Write status values as This option can be used to decide whether status values e g GPS Position Update should be written as text or as a number For graphing the values a number is needed Ey Oxford Technical Solutions RT Post process User Manual QOoxrs Output File page Three different files can be output by RT Post process The Main Output file starts and ends at the times defined on the Output Configuration page The Auto Increment file starts and stops based on the event input of the RT The Tri
4. 2 Select Data Source page RT Post Process Wizard x E Select Data Source RT3000 Inertial and GPS Read data file Measurement System Choose where the initial settings should be read from Move the mouse over a specific item to see the hint for that item Step 1 of 9 Select Raw Data File from RT System b C Select Raw Data File from Folder Select Raw Data File Working Directory C Select NCOM File from Folder Base Station Process Page Select Fields IP Add f RT Syst Output Config discs azak Output File 195 0 0 106 AT 2000 v Finish Page Confidenthy Accurately oq toes lE ID 1110311480 Select Data Source page Three data sources can be selected RD files can be selected from a folder or can be copied off an RT using FTP If an NCOM file is available then this can be converted to text format CSV etc It is not possible to reprocess an NCOM file and change the settings that were used Each option is described below Select Raw Data File from RT System This option should be used to copy an RD file from the RT using FTP After selecting this option enter the IP address of the RT 10 Oxford Technical Solutions RT Post process User Manual Qoxrs that you want to read the files from If the software can receive UDP data from the network then it will list all of the RTs that are currently broadcasting NCOM Click Next to see the files on the RT Select Raw Dat
5. Raw GPS Data Output Config Output File Finish Page Processed KF File Confidently e Accurately SS ee Dev ID 1107121420 lt Back Next gt Cancel To save the raw GPS data click on the Save As button in the Extract Raw GPS Data group box After the raw data has been processed and formatted in the KP format enter the filename in the Processed KP file edit box or use the button to select the file a Oxford Technical Solutions RT Post process User Manual Oaxrs Saving KP files from GrafNav Data is exported from GrafNav using the Export Wizard in the Output menu To export in the KP format it is necessary to have the GrafNav configuration file for the KP format this file is called OxTS KP format prf It is installed in the Program Files OxTS folder and it needs to be copied to the Novatel WayptGPSxxx folder so that GrafNav can find it After the file is copied then the OxTS KP format will be listed in the Export wizard in GrafNav Process Page The Process page has the option to review the configuration settings before the processing begins Figure 10 shows the Process page Figure 10 Process Page RT Post Process Wizard x m Process Page In ertia l Process the Raw Data file with your choosen settings Inertial Fee Select the options for processing the Nee Inertial RD file System Review Configuration Step 5 of 9 Sel
6. deviation of the bias of the accelerometer bias stdev in the IMU Z axis in m s Revision 111102 Ea Table 9 ACY and ACR file format field description columns 15 to 29 Column 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Field Heading stdev Pitch stdev Roll stdev Gyro X bias Gyro X bias stdev Gyro Y bias Gyro Y bias stdev Gyro Z bias Gyro Z bias stdev Gyro X scale factor Gyro X scale factor stdev Gyro Y scale factor Gyro Y scale factor stdev Gyro Z scale factor Gyro Z scale factor stdev Description The estimated accuracy of heading in degrees The estimated accuracy of pitch in degrees The estimated accuracy of roll in degrees The bias or offset applied to the gyro in the IMU X axis in degrees s The estimated standard deviation of the bias of the gyro in the IMU X axis in degrees s The bias or offset applied to the gyro in the IMU Y axis in degrees s The estimated standard deviation of the bias of the gyro in the IMU Y axis in degrees s The bias or offset applied to the gyro in the IMU Z axis in degrees s The estimated standard deviation of the bias of the gyro in the IMU Z axis in degrees s The scale factor or gain applied to the gyro in the IMU X axis The estimated standard deviation of the scale factor of the gyro in the IMU X axis The scale factor or gain applied to the gyro in the IMU Y axis The estimated sta
7. in degrees that defines the relationship between the NED North East Down co ordinates and the XYZ axes The angular rate along the X direction in degrees s The angular rate along the Y direction in degrees s The angular rate along the Z direction in degrees s Note 1 In the PRN file the axis will refer to the axis of the IMU and in the ROT file the axis will refer to the axis of the vehicle The orientation page of RT Config or it config will define the relationship between the IMU and the vehicle axes An example line from the PRN or ROT file is 1649 303259 8000 51 92932584 1 25077123 123 581 8 954 1 727 0 210 2 130 0 591 10 505 10 83 0 06 0 10 2 73 1 12 0 95 aA Oxford Technical Solutions RT Post process User Manual ACY and ACR file format The ACY and ACR files are output by blended exe and have the same format as each other They both contain accuracy and state information that can be used as an indicator on how accurate the RT believes it is The difference between the files is that the ACY file is in the IMU co ordinate frame and the ACR file is in the vehicle co ordinate frame These files are always output with a data rate of 1Hz The files are written in text format space separated with one line per second Each line is terminated with a lt CR gt lt LF gt pair The fields are listed in Table 8 Table 8 ACY and ACR file format field description columns 1 to 14 Column Field Descrip
8. midnight and always in UTC time to match the output of the NMEA ZDA message 2 Latitude This is the latitude in radians 3 Longitude This is the longitude in radians 4 Altitude This is the ellipsoidal altitude regardless of the configuration in RT Config or i config It is output in metres 5 Roll This is the roll angle in radians 6 Pitch This is the pitch angle in radians 7 Heading This is the heading in radians An example line from the OTA file is 382899 750 0 897 14643 15 0 0082070546 36 335 0 0419 0 0749 2 2700 Note that the altitude in this example is below the ellipsoid Output files from blended exe There are several output files created by blended exe The NCOM file which has its own manual is the main output file There are some output files in text format that can also be used Many of the files are used by the engineers at OxTS for developing the algorithms and their format is not described here Future versions of RT Post process may clean up some of the files after processing 30 Oxford Technical Solutions RT Post process User Manual Qox 73 Table 6 Output files from post processing File extension Description ncom This is the main output file that contains all the measurements This is the only file that is combined from forwards and backwards processing mcom This is an extended version of ncom that has space for some additional measurements prn rot These files are the navigation
9. velocity in the up direction in m s 18 Velocity North The standard deviation of the velocity in the north direction in m s stdev 19 Velocity East stdev The standard deviation of the velocity in the east direction in m s 20 Velocity Up stdev The standard deviation of the velocity in the up direction in m s An example line from the KP file is 1464 225945 500000 1 8 51 56 36 12254 1 14 53 29741 180 0011 0 012804 0 010920 0 022326 0 020 0 002 0 006 0 156128 0 133996 0 261583 EI Oxford Technical Solutions RT Post process User Manual Qoxrs Revision History Table 12 Revision History Revision Comments 110907 Initial version Revision 111102
10. Inertial and GPS Measurement Systems a RT Post Process Wizard Select Data Source RT3000 Choose where the initial settings should be read from Inertial Wahib Read data file Measurement System Hint Choose where to get files from Step 1 of 9 Select Raw Data File from RT System _ Select Data Source C Select Raw Data File from Folder Select Raw Data File Working Directory Base Station Process Page Select Fields P f RT Syst Output Config IP Address of RT System Output File 195 0 0 106 RT2000 Finish Page Confidently Accurately C Select NCOM File from Folder Cancel mus lE ID 110713 14a0 RT Post process User Manual Confidently Accurately Vaxrs Legal Notice Information furnished is believed to be accurate and reliable However Oxford Technical Solutions Limited assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under any patent or patent rights of Oxford Technical Solutions Limited Specifications mentioned in this publication are subject to change without notice and do not represent a commitment on the part of Oxford Technical Solutions Limited This publication supersedes and replaces all information previously supplied Oxford Technical Solutions Limited products are not autho
11. Inertial GPS Figure 11 Process console application blended exe 7 E C Program Files 86 OxTS blended exe tolta Rotated blended system output t Rotated blended system accuracy output C Data Test mobile h System configuration C Data Test mobile cfg Output displacement vector lt defaults gt INCOM output log C Data Test mobile om Zero velocity update position vector lt defaults gt Zero velocity update position accuracy lt defaults gt No slip update position vector Data Test mobile ns No slip update position accuracy Data Test mobile ns Nehicle alignment accuracy Data Test mobile Wheel speed update position vector Data Test mobile ws Wheel speed update position accuracy Data Test mobile ws Local Cuser defined gt reference frame defaults gt Command log file C Data Test mobile f Differential corrections file lt defaults gt Rinex file lt defaults gt MCOM output log C Data Test mobile om Attempting to open C Data Test mobile rd Completed 61 19 3MiB of 31 9MiB The processing creates an NCOM file that can be loaded into RT View and is used for the export pages further on in the RT Post process wizard After the processing finishes the Select Fields page will be shown Select Fields page The Select Fields page can be used to select which fields are used to export the data Currently three different file types can be exported in text format These are CSV
12. RD file to avoid confusion The configuration that is currently on the RT will be transferred using RT Post process to the working directory This configuration can be different to the configuration that was used in real time and this can lead to incorrect results RT Post process can extract the configuration that was used when the RD file was written to the RT a Oxford Technical Solutions RT Post process User Manual QOoxrs It is possible to post process the GPS data using external software This is easiest using GrafNav but other software can be used for example GAMIT GLOBK TRACK Contact OxTS if you want to use other software Before processing the data RT Config or i config can be run The configuration can be checked and changed before processing the data This can be useful for fixing configuration problems for applying a better configuration e g a better known antenna position for displacing the output to another location etc The data is processed using a Win32 console application called blended exe This is developed at OxTS separately from the user application It is possible to run this program as part of a batch file so that lots of RD files can be processed together Once blended has finished an NCOM file will have been created This can be loaded into RT View or exported to text format from RT Post process CSV POS and OTA formats can be written The text files can be the whole of the NCOM file or parts of it Th
13. a File from Folder This option should be used if the RD file is already on the PC After selecting this option the Raw Data File group box will replace the IP Address of RT System group box Select the RD file from a folder and click Next The software will jump straight to the Working Directory page Select NCOM File from Folder This option can be used to bypass the reprocessing stage and export the NCOM file to text format After selecting this option the NCOM File group box will replace the IP Address of RT System group box Select the NCOM file from a folder and click Next The software will jump straight to the Select Fields page Select Raw Data File page The Select Raw Data File page is only shown if the Select Raw Data File from RT System option is chosen from the Select Data Source page Figure 3 shows the page with 5 files listed Figure 3 Select Raw Data File page RT Post Process Wizard l m Select Raw Data File RT3000 Select the Raw Data file to transfer and process Inertial and GPS Measurement System Raw Data File Move the mouse over a 070905_142102 1d specific item to see the Sion ofS Date Time FileSize __ hint for that item o 05 09 2007 14 21 02 56511 KB PAP eRe 05 09 2007 14 18 11 1002KB gt 05 09 2007 14 18 04 6101 KB 05 09 2007 14 15 56 3KB 05 09 2007 14 15 15 132KB Working Directory Base Station Process Page Select Fields Output Conf
14. and to select the base station file See below for a description of the base station location Select Reprocessed file KP This option can be used with other GPS processing software It will be available even if GrafNav is not installed When this option is selected an option to extract and save the raw GPS information to a file will be available The format that the file is written in depends on the receiver used in the RT or external receiver in the Inertial More information is provided for this below Configuring the Base Station Location It is important to know the position of the base station precisely If an approximate location is used then any error in the base station location will be included in the position of the RT This can be useful if you want to offset the RT s position to a slightly different location If you are trying to plot the RT on a map then it is important to know the base station location on the map Revision 111102 15 RT Post process is expecting the co ordinates of the base station to be in the WGS 84 reference frame It is best to measure the location of the base station in this reference frame and then transform the outputs of the RT to the desired co ordinate frame afterwards Figure 7 shows the Base Station Location group box Rather than entering the base station location each time the base station locations are saved and read from a directory so that they can be reused Figure 7 Base Stati
15. ased application for reprocessing data from the RT and Inertial products from OxTS With RT Post process you can Copy raw data RD files from an RT or an Inertial onto your computer Apply different configurations and optimise the processing to get the best performance e Process the inertial data forwards and backwards in time in order to minimise the drift when GPS is not available Use differentially corrected GPS data requires other software Raw GPS data can be exported from RT Post process combined with base station data then read back into RT Post process and combined with the inertial data Convert the binary output files into text formats e Crop or divide the output files into smaller sections and change the data rate of the files RT Post process is a wizard based application that guides you through the steps of post processing the data Part of the process uses RT Config or i config to examine or change the configuration It should be relatively easy to use RT Post process and this manual serves mainly to explain some of the detail behind the options This manual refers to the RT throughout However RT Post process has been designed to work with the Inertial as well as the RT products All the features of RT Post process will work correctly with the Inertialt except where the manual explicitly states otherwise File storage within the RT The RT usually logs a file to its internal storage whenever it
16. button to move to the Process page Note that if there is a KP file in the directory then it will not get deleted and so the base station data in the KP file will get used even if this option is selected Select Novatel Base Station This option can be used if a base station file in Novatel s format is available The OxTS GPS Base normally saves its measurements in Novatel s format When this option is selected the software will show an option to select the base station location and to select the base station file See below for a description of the base station location Select RINEX Base Station This option can be used if a RINEX base station is available RINEX is the most common type of base station When this option is selected the software will show an option to select the base station location and to select the base station file See below for a description of the base station location Select Waypoint Base Station file This option can be used if a base station file in Waypoint s GrafNav format GRB is available Note that it is important to have the right sample rate in the GRB file This must be at the same data rate as the GPS receiver For most RT products this is 2Hz For the RT2500 and RT2502 the data rate should be 4Hz For Inertial the data rate must be the same as the data rate of the raw data being logged by the Inertial When this option is selected the software will show an option to select the base station location
17. e Extract Config Files From RD File checkbox If this is unchecked and the RD file has been copied from the RT then the current configuration files that are on the RT will be copied to the working directory Note that the current configuration files on the RT may have been changed since the RD file was created and they may not have the correct configuration in them It is important to make sure that the correct configuration files are used One of the main reasons why people have problems with RT Post process is because they do not have the correct configuration files with the RD file when they start processing Take care to make sure you have the correct configuration files before starting to process the RD file Revision 111102 Base Station RT Post process is able to use GPS measurements that have been post processed When using an Inertial the software from the GPS receiver manufacturer should be used to post process the GPS Normally RT Post process will use GrafNav to post process the GPS measurements If GrafNav is not installed then the software will jump over this page and go straight to the Process page It is necessary to go back to this page by going to the Process page then clicking on the Base Station text in the steps on the left hand side of the page RT Post process only covers the basic features of processing in GrafNav It is designed to be quick and simple When more advanced features are needed then it wil
18. e event input to the RT can be used to define the start and stop of the text files and it can be used to write a text file at the times of the events Revision 111102 fa Oaxzs Minimum System Requirements The minimum system specifications required to support the software are listed below e 512MB SDRAM e 32 bit or 64 bit operating system e Windows XP Windows Vista Windows 7 he Oxford Technical Solutions RT Post process User Manual Qoxrs Installation The software will be delivered either on a CD or as a zip file The zip file does not need to be uncompressed before running the setup file Double click RT Setup exe to start the software setup This will install the RT Software Suite which contains the following programs e Enginuity e RT Config e RT Post Process e RT View If the unit is an Inertial double clicking I Setup exe will install the Inertial Software Suite which contains the following programs e Enginuity e I Config e RT Post Process e RT View Both software suites can be installed at the same time Revision 111102 RA Operation An overview of the workflow for RT Post process was given in the introduction This section builds on the workflow and describes each step in more detail To run RT Post process go to the Windows Start menu select All Programs OxTS and click on RT Post process This will run the software Figure 2 shows the window that will be displayed Figure
19. ect Data Source Process Combine Forwards Backwa Select Raw Data File Working Directory E Base Station V Clean up directory after processing Select Fields Display results in RT View after processing Output Config Output File Finish Page Confidenthy Accurately eee ae Dev ID 111031 14a0 lt Back H Cancel To review and change the configuration or settings click on the Review Settings button This will run RT Config or it config where the settings can be changed Some of the settings do not apply to post processing and these are not automatically identified Revision 111102 19 Oaxrs by RT Config For example it is not possible to change the differential corrections used during post processing Two processing techniques are offered by RT Post process These are listed in Table 1 Table 1 Processing techniques in RT Post process Technique Description Simulated real time This technique processes the data forward in time using an algorithm that is virtually identical to the real time processing The only difference is that the Kalman filter in the real time processing takes time to process so its corrections are applied between 30 and 100ms later This occasionally leads to differences in the data Combine Forwards This technique uses the best processing techniques available including Backwards processing the data forwards and backwards in time and combinin
20. ference Units listed below Seconds after initialising This is the number of seconds that should be skipped after initialisation of the RT The second line selects the duration for the file or a time when the file should stop being output Table 3 shows the stop conditions that can be used Revision 111102 Vaxrs Table 3 Output Conditions End Time Condition Description Duration in seconds This sets the duration of the output file in seconds Stop Time hh mm ss This sets the stop time of the day in the Time Reference Units listed below The other options are listed below Output data rate The data rate can be cut down decimated from the original data rate in the NCOM file No filtering is used to do this instead epochs are simply not written to the output file The dropdown list should automatically identify 250Hz if a 250Hz NCOM file is used Velocity Units This option can be used to change the velocity units Distance Units This option can be used to set the distance units RT Post process will inherit the distance hold or free mode from the communication page of Enginuity In hold mode the distance will not increment when the velocity output becomes sufficiently small so that the RT has a high probability of being stationary Acceleration Units This option can be used to set the acceleration units Note that the value for G is fixed G is not a useful value for acceleration measurement because
21. g the results together For backwards processing to work the file must be able to initialise backwards Processing using the Combine Forwards and Backwards technique gives better results but it is essential that the data can be initialised backwards Output MCOM file An MCOM file can be output while processing This option is only available using the Simulated real time technique This file format is supported for marine applications and is not used by most OxTS applications Clean up directory after processing RT Post process will generate a lot of files during processing which take up space on the disk These are placed in different sub directories To clean up these files after processing select this option The software will leave the kp file from any GPS processing in place so that the GPS does not need to be reprocessed Display results in RT View after processing After processing the results can be displayed in RT View automatically Checking this option will automatically launch RT View after the processing completes To start processing the data click the Process button This will launch a console application blended exe that is used to blend the inertial and GPS data together and give the optimal output This application is shown in Figure 11 When processing forwards and backwards in time two console applications will be displayed EJ Oxford Technical Solutions RT Post process User Manual
22. gger file has one line for each event input on the RT The Output File page is shown in Figure 14 Figure 14 Output File page RT Post Process Wizard x a Select Output File Select ASCII output files WV Export to Main Output file Hint RT2000 Inertial and GPS Measurement C Data T est mobile csv E Enter filename and path tdd J Export to Auto Increment file eee Step 8 of 9 C Data T est mobile 000 E Start new Auto Increment file on Select Data Source oO Select Raw Data File Working Directory Stop Auto Increment file on Base Station a E Process Page Select Fields Output Config gt Export to Trigger file C Data T est mobileT rig csv ea Finish Page Add entry to file on each of these triggers Confidently a Vv a Accurately eee E tos DEV ID 110713140 lt Back IIL _Eancel Each option is listed below More than one option can be used at the same time Export to Main Output file This option should be used to output one file from the start time to the end time as defined by on the Output Configuration page Use the button to select the filename Note that RT Post process will not overwrite an existing CSV file and the field will be blank if the default file exists This file will need to be deleted before RT Post process can output Export to Auto Increment file This option can be used to divide the NCOM file into multiple
23. ig Output File Finish Page Confidently Accurately B SS Fe Dev ID 111031 14a0 lt Back i Cancel Revision 111102 in Oaxrs The date time and file size of each file on the RT are listed These are the start time of the file in GPS time very similar to UTC when the GPS receiver in the RT found time As an approximation the RT will log about 20MB per hour though this can change a lot depending on the RT Single antenna systems log less data and dual antenna Inertial systems can log more To upload a file from the RT select the file and click Next The software will use FTP to get the file from the RT and save it in a temporary directory The FTP RD file window in Figure 4 will show the progress Figure 4 FTP RD file window FTP RD file 070905 _141804 rd mym Received 3 13M out of 5 96M Working Directory page The working directory is where the data will be processed The output files will be written to this directory The configuration files should be placed in this directory before processing It is important to only have one RD file in each directory while processing The configuration files all start with the filename mobile This means that only one configuration can exist in each directory When RT Post process is running it will create a sub directory for its work and the sub directory has a fixed name with fixed filenames within that sub directory For
24. in the IMU Z axis in metres 36 Dual antenna The heading angle rotation between the IMU and the dual antenna heading GPS in degrees 37 Dual antenna The estimated heading angle rotation accuracy between the IMU heading stdev and the dual antenna GPS in degrees 38 Dual antenna pitch The pitch angle rotation between the IMU and the dual antenna GPS in degrees 39 Dual antenna pitch The estimated pitch angle rotation accuracy between the IMU and stdev the dual antenna GPS in degrees Other fields at the end of the ARY and ACR files should be ignored An example line from the ACY or ACR file is 1648 487956 000 0 00004630 0 00006105 10 001 0 176 0 171 0 105 0 00002 0 00500 0 00000 0 00500 0 00000 0 00500 1 639 1 643 5 785 0 0016 0 5003 0 0042 0 4999 0 0028 0 4999 0 0000 0 0100 0 0000 0 0100 0 0000 0 0100 0 700 0 100 0 000 0 100 0 000 0 100 34 630 5 000 90 000 4 991 0 000 5 000 0 0000 0 0000 0 0000 0 0000 0 0000 0 0000 KP Input File The KP input file is used to read post processed GPS data into blended exe so that it can be combined with the inertial data GPS is often post processed so that it can be corrected by a base station If there is a measurement in the KP file then it will be used instead of the real time measurement from the GPS When there is no measurement in the KP file then the real time measurement from the GPS will be used instead Revision 111102 EI Oaxrs The KP file is in text format with space separated val
25. ing to be used On trains it is common to have a configuration that will not initialise until the user tells the RT which direction it is going This will work when processing backwards but it is essential to have a command at the end of the file to tell the RT which direction it was going Some commands sent to the RT while running will cause problems For example if the local co ordinates roll pitch or slip angles are changed while processing using the Quick Config in Enginuity then combined processing will not work correctly It is essential to have a configuration RD file set the configuration then use a separate RD file for the tests EJ Oxford Technical Solutions RT Post process User Manual Qoxrs File formats This is an advanced section of the manual and is not needed for many applications Most of the files described here are output files from either blended exe left in the working directory or the text files from RT Post process The input files include the RD file the configuration files and the KP file The only input file described here is the KP file POS file The POS file is output by RT Post process and is used with several laser scanning systems It includes the time position and orientation so that laser scans can be corrected Although some fields can be dropped for the file to be correct all the fields should be output by RT Post process use the Select All button to select all the fields befo
26. is running This file contains the configuration the raw data from the inertial sensors and the GPS measurements It does not normally include processed NCOM data RT Post process is needed to convert an RD file to an NCOM file When the RT boots it will start logging a file called mobile rd When GPS time is available the file will get renamed to yymmdd_hhmmss rd where yy is the year the first mm is the month dd is the day in the month hh is the hour the second mm is the minutes and ss is the seconds GPS time is very close to UTC or GMT The filename does not have any local time offset applied to it o Oxford Technical Solutions RT Post process User Manual Qoxrs When the disk space becomes full then the RT will erase the oldest RD file RD files can be deleted by the user using FTP software If the current RD file being written is deleted then the RT will continue to write to this file but it will no longer have all the post processing functionality that other RD files have the configuration files will be missing from the start The files are all put in the user partition of the storage in the RT and this partition can be accessed through FTP RT Post process includes an FTP server that can be used to view the files Other FTP software for example Explorer can be used to view the files as well For FTP access an anonymous login can be used Alternatively use the login name user and
27. l be necessary to extract the raw GPS data and process in GrafNav s graphical interface Figure 6 shows the Base Station page In Figure 6 post processing is not possible because RT Post process does not support post processing using the GPS receiver that was attached to the Inertial See Reprocessing GPS data outside of RT Post process for a solution to this Figure 6 Base Station page RT Post Process Wizard Eci Base Station I ne rt la i Select the Base Station data directory Inertial thie WayPoint GrafNay Version 8 30 Measurement Select the appropriate racy Don t Process Base Station data option for Base Station e file processing using Step 4 of 9 rs WayPoint module Select Data Source r Select Raw Data File Working Directory C Select Reprocessed file KP gt Process Page Select Fields Output Config Output File Finish Page Confidenthy Accurately Ee Dey ID 111031 14a0 lt Back Cancel p Oxford Technical Solutions RT Post process User Manual Qox 73 If GrafNav is not found then use the button to search for the directory where GrafNav is located Once a supported version of GrafNav is found then the radio buttons will be enabled RT Post process currently does not support GrafNav version 8 2 Novatel have declined to release the API for this version Don t Process Base Station data This option can be used to ignore base station data Use the Next
28. lems when processing backwards Sometimes the GPS works poorly in the garage causing the system to initialise when it shouldn t The end of the file should have a clean brake from a suitable velocity to a standstill in a straight line It should be in a good GPS environment This is the same as initialising at the beginning of the file but now the vehicle should be braking instead of accelerating The vehicle should be going forwards during the brake Do not reverse above the initialisation speed into a parking space at the end of a file A warm up period at the end of the file will help the Kalman filter achieve the best results Like the warm up at the start of the file the best warm up is a series of figure 8 s in open sky conditions at different speeds with some straight line constant speed motion in the middle of the figure 8 The end of the file should have good GPS conditions even if a warm up is not possible Rather than ending the test in the middle of city conditions drive out to more open sky conditions for a few minutes before turning off the RT Systems requiring static initialisation should remain stationary in open sky at the end for long enough so that the static initialisation will work Static initialisation rarely takes longer than 1 minute in open sky conditions especially with the pitch constraint However it may be best to remain stationary for at least 5 minutes or longer if static initialisation is go
29. measurements output in text format Their format is described below acy acr These files contain accuracy information and some of the states from the Kalman filter Their format is described below qcf This file lists all the commands that were sent to the command interface of the RT while it was running The software also makes some files called result and these are used by the developers They contain information about the inertial sensors early on during the processing that can be used to improve the performance during the warm up period PRN and ROT file format The PRN file and the ROT files are output by blended exe and have the same format as each other They both contain the outputs of the inertial measurement system The difference between the files is that the PRN file outputs the inertial measurements in the IMU co ordinate frame and the ROT file outputs the inertial measurements in the vehicle co ordinate frame For most applications the ROT file is more useful The files are written in text format space separated with one line for each time epoch Each line is terminated with a lt lt CR gt lt LF gt pair The fields are listed in Table 7 Revision 111102 Ea Oaxrs Table 7 PRN and ROT file format field description Column 1 10 11 12 13 14 15 16 17 Field GPS Week GPS Time of week Latitude Longitude Altitude Velocity North Velocity East Velocity Down Accelerati
30. ndard deviation of the bias of the gyro in the IMU Y axis The bias or offset applied to the gyro in the IMU Z axis The estimated standard deviation of the bias of the gyro in the IMU Z axis Note 1 In the ACY file the axis will refer to the axis of the IMU and in the ACR file the axis will refer to the axis of the vehicle The orientation page of RT Config or i config will define the relationship between the IMU and the vehicle axes EI Oxford Technical Solutions RT Post process User Manual Table 10 ACY and ACR file format field description columns 30 to 39 Column Field Description 30 GPS antenna lever The lever arm from the IMU measurement point to the GPS arm X antenna phase centre in the IMU X axis in metres 31 GPS antennalever The estimated accuracy of the lever arm from the IMU arm X stdev measurement point to the GPS antenna phase centre in the IMU X axis in metres 32 GPS antenna lever The lever arm from the IMU measurement point to the GPS arm Y antenna phase centre in the Y axis in metres 33 GPS antennalever The estimated accuracy of the lever arm from the IMU arm Y stdev measurement point to the GPS antenna phase centre in the IMU Y axis in metres 34 GPS antenna lever The lever arm from the IMU measurement point to the GPS arm Z antenna phase centre in the IMU Z axis in metres 35 GPS antennalever The estimated accuracy of the lever arm from the IMU arm Z stdev measurement point to the GPS antenna phase centre
31. on Location group box RT Post Process Wizard Ea E Base Station RT2000 Inertial UTR ayPoint GrafNav Version 7 80 Measurement Select the appropriate rico Don t Process Base Station data option for Base Station file processing using WayPoint module Select the Base Station data directory Select Novatel Base Station Select RINEX Base Station file Select WayPoint Base Station file Step 4 of 9 Select Data Source Select Raw Data File Working Directory e o Select Reprocessed file KP gt Process Page Select Fields Base Station Location Output Config Output File office roof new file format Edit Location Finish Page Novatel Base Station File O ELUTA C Data T est Base bin if Accurately D SS To select a base station location for this data set use the dropdown list This lists all the base station files in the directory To change the directory press the button and select a new directory the dropdown list will be updated To select a new location or to edit a current location use the Edit Location button This opens the Base Station Location dialog box as shown in Figure 8 16 Oxford Technical Solutions RT Post process User Manual Qoxrs Figure 8 Base Station Location dialog Base Station Location xn Base Station Name ifletfed EN els J Decimal Deg Deg Min Sec Lat N 51 92918249 deg Lon w
32. on X Acceleration Y Acceleration Z Heading Pitch Roll Angular Rate X Angular Rate Y Angular Rate Z Description The GPS Week starting with 6th January 1980 as week 0 The value in this field is always larger than 1023 so it includes the first GPS roll over The satellites only transmit 10 bits for the week This is the number of seconds into the week The transition for GPS Time starts between Saturday night and Sunday morning The latitude in decimal degrees This is normally in the WGS84 co ordinate system The longitude in decimal degrees This is normally in the WGS84 co ordinate system The altitude in metres This will be the geoidal altitude by default but it can be the ellipsoidal altitude if the default configuration in RT Config has been changed The velocity in the north direction in m s The velocity in the east direction in m s The velocity in the down direction in m s This is the opposite direction to altitude It is positive if the altitude is decreasing The acceleration in the X direction in m s The acceleration in the Y direction in m s The acceleration in the Z direction in m s This is the heading angle in degrees that defines the relationship between the NED North East Down co ordinates and the XYZ axes This is the pitch angle in degrees that defines the relationship between the NED North East Down co ordinates and the XYZ axes This is the roll angle
33. output files using the event input to the RT Options to start and stop each file are in the group boxes below the checkbox The file can be started and stopped on the rising edge or the falling edge of the event input An example showing the event input and the output files is shown in Figure 15 Revision 111102 EI Figure 15 Auto Increment file output Q o o D O DO D O ke O O T SD uy cate ui g 2 E D p a v 2 S 2 2 iy ae uw In this example RT Post process would be set to start a new Auto Increment file on the falling edge and to stop the Auto Increment file on the rising edge When the first falling edge in the file is found then the first file will be created when the rising edge is found then the first file is closed The length of the file depends on the duration between the two event inputs This example is typical of a switch being placed between the event input and ground when the switch is closed the output file starts and when the switch is opened then the output file stops An internal pull up resistor in the RT pulls the event input high causing a rising edge when the switch is open If the falling edge or rising edge is used for both starting and stopping the Auto Increment file then the first event will start the file and the second event will stop the file RT Post process will interpolate the first and last packets in the Auto Increment file to the e
34. post processing in the external GPS receiver post process it format it in the KP file format and then import it into RT Post process Because the Inertial has its own GPS receiver s all the measurements Revision 111102 are already time stamped to GPS time all the measurements can be combined together correctly GrafNav can be used to post process receivers other than those made by Novatel but it will be necessary to export the receiver s data and use GrafNav s user interface rather than relying on RT Post process to do this Other software that can be used includes TRACK from MIT s GAMIT GLOBK suite This software is very good with long base lines OxTS has a tool that can convert the output of TRACK so that it can be used with RT Post process Figure 9 shows the Extract Raw GPS Data group box and the Processed KP file group box Figure 9 Extract Raw GPS Data group box RT Post Process Wizard x pel Base Station RT2000 inertial SUR WayPoint GrafNav Version 7 80 Measurement Select the appropriate ELE C Don t Process Base Station data option for Base Station file processing using WayPoint module Select the Base Station data directory C Select Novatel Base Station C Select RINEX Base Station file Select Data Source c on Seleci Raw Data File Select WayPoint Base Station file Working Directory Select Reprocessed file KP Step 4 of 9 Process Page Select Fields Extract
35. re writing the file The file is written in text format with space separation between the fields and a lt CR gt at the end of each line Table 4 POS file format field description Column Field Description 1 Time of day This is the time of day in seconds starting at midnight 2 Latitude This is the latitude in decimal degrees 3 Longitude This is the longitude in decimal degrees 4 Altitude This is the altitude in metres It will be the ellipsoidal or geoidal altitude depending on the configuration in RT Config or it config 5 Roll This is the roll angle in degrees 6 Pitch This is the pitch angle in degrees 7 Heading This is the heading in degrees An example line from the POS file is 37299 750 51 40270413 0 47022959 10 740 2 400 4 290 130 060 OTA file The OTA file is output in the Optech ASCII format This is a text format that can be used with Optech s software so that the laser points can be geo referenced It includes the time position and orientation Although some fields can be dropped for the file to be correct all the fields should be output by RT Post process use the Select All Revision 111102 EI Oaxzs button to select all the fields before writing the file The file is written in text format with comma separation between the fields No header is included Table 5 OTA file format field description Column Field Description 1 UTC Time of day This is the time of day in seconds starting at
36. rised for use as critical components in life support devices or systems without express written approval of Oxford Technical Solutions Limited All brand names are trademarks of their respective holders Copyright Notice Copyright 2011 Oxford Technical Solutions Revision Document Revision 111102 See Revision History for detailed information Contact Details Oxford Technical Solutions Limited 77 Heyford Park Upper Heyford Oxfordshire OX25 5HD England Tel 44 0 1869 238 015 Fax 44 0 1869 238 016 http www oxts com mailto info oxts com al Oxford Technical Solutions RT Post process User Manual Qoxrs Table of Contents Introduction File storage within the RT Post processing workflow 5 Minimum System Requirements 8 Installation 9 Operation 10 Select Data Source page 10 Select Raw Data File page 11 Working Directory page 12 Base Station 14 Configuring the Base Station Location 15 Reprocessing GPS data outside of RT Post process 17 Saving KP files from GrafNav 19 Process Page 19 Select Fields page 21 Output Configuration page 22 Output File page 25 Finish page 21 Requirements for Combined forwards backwards processing 28 File formats 29 POS file 29 OTA file 29 Output files from blended exe 30 PRN and ROT file format 31 ACY and ACR file format 33 KP Input File 35 Revision History 37 Revision 111102 a Vaxrs Introduction RT Post process is a wizard b
37. the password user The configuration files all starting with mobile are also stored in this folder These should not be deleted They are modified by RT Config or i config and it is best to always use this software to update the configuration Post processing workflow Figure 1 shows the workflow for processing an RD file The workflow uses a combination of RT Post process and RT Config or i config for an Inertial The workflow is relatively simple and is as close to a one click approach as we could make it Revision 111102 E Figure 1 Processing workflow overview for RT Post process RD files Working directory containing RD file Configuration files mobile cfg Optional GPS Post processing KP file amp Q x O pms a amp D O O 4 Lu Optional RT Config to change configuration using RT Post process Explorer etc Processing engine blends inertial and GPS data using local configuration NCOM file E NCOM to CSV export Text output files in CSV and other formats CSV file trigger file CSV files CSV from triggers At the start of the workflow an RD file will be transferred from the RT via FTP either using RT Post process or using other FTP software The file should be placed in a working directory where lots of files will be created It is best to use one directory for each
38. these reasons you can only process one RD file in each directory Putting two RD files in the same directory and then processing them at the same time will lead to confusion If the RD file is already in a different directory then the software will copy the RD file to the working directory before processing This can be useful when trying to process the file multiple times with different configurations Figure 5 shows the Select Working Directory page al Oxford Technical Solutions RT Post process User Manual Qoxrs Figure 5 Select Working Directory page RT Post Process Wizard x Working Directory l ne rt la i Select a directory to put all the files in Inertial and GPS Measurement Select Working Directory Use a new or empty ki IXTSNRT DATANO7OBO5 142102 directory to work in The Raw Data file and the Post Processed NCOM file will be put in this dir ector y Step 3 of 9 Select Data Source Select Raw Data File Extract Config Files From RD File Base Station Process Page Select Fields Output Config Output File Finish Page Confidenthy Accurately a E Somes lE D 111031 14a0 lt Back Cancel Either enter the directory name in the edit box or use the button to select the working directory If the directory does not exist then it will be created It is possible for the software to extract the configuration files from the RD file To do this check th
39. tion 1 GPS Week The GPS Week starting with 6th January 1980 as week 0 The value in this field is always larger than 1023 so it includes the first GPS roll over The satellites only transmit 10 bits for the week 2 GPS Time of week This is the number of seconds into the week The transition for GPS Time starts between Saturday night and Sunday morning 3 Latitude stdev The estimated standard deviation of latitude in degrees 4 Longitude stdev The estimated standard deviation of longitude in degrees 5 Altitude stdev The estimated standard deviation of altitude in metres 6 Velocity North The estimated standard deviation of velocity in the north direction stdev in m s 7 Velocity East stdev The estimated standard deviation of velocity in the east direction in m s 8 Velocity Down The estimated standard deviation of velocity in the down direction stdev in m s 9 Accelerometer X The bias or offset applied to the accelerometer in the IMU X axis bias in m s 10 Accelerometer X The estimated standard deviation of the bias of the accelerometer bias stdev in the IMU X axis in m s 11 Accelerometer Y The bias or offset applied to the accelerometer in the IMU Y axis bias in m s 12 Accelerometer Y The estimated standard deviation of the bias of the accelerometer bias stdev in the IMU Y axis in m s 13 Accelerometer Z The bias or offset applied to the accelerometer in the IMU Z axis bias in m s 14 Accelerometer Z The estimated standard
40. ues and a lt CR gt lt LF gt at the end of each line Each line represents one time epoch Table 11 lists the fields in the KP file All of the fields in the file are mandatory Table 11 KP file format Column Field Description 1 GPS Week The GPS Week starting with 6th January 1980 as week 0 The value in this field is always larger than 1023 so it includes the first GPS roll over The satellites only transmit 10 bits for the week 2 GPS Time of week This is the number of seconds into the week The transition for GPS Time starts between Saturday night and Sunday morning 3 Quality number This field is not used by blended exe 4 Number of satellites This is the number of satellites used in the solution 5 Latitude degrees The degrees component of latitude 6 Latitude minutes The minutes component of latitude 7 Latitude seconds The seconds component of latitude 8 Longitude degrees The degrees component of longitude 9 Longitude minutes The minutes component of longitude 10 Longitude seconds The seconds component of longitude 11 Ellipsoidal Altitude The ellipsoidal altitude in metres 12 North stdev The standard deviation of the latitude in metres 13 East stdev The standard deviation of the longitude in metres 14 Altitude stdev The standard deviation of the altitude in metres 15 Velocity North The velocity in the north direction in m s 16 Velocity East The velocity in the east direction in m s 17 Velocity Up The
41. xact times of the event input The other measurements are aligned to the GPS clock The 000 button shown next to the filename edit box for the Auto Increment file can be used to set the value appended to the filename for the first file that is output The button can be used to select the filename Export to Trigger file This option can be used to write a file with one line records for every event input For example the event input may be connected to the shutter of a camera and each time the camera shutter closes an event occurs probably a falling edge followed by a rising edge and a line can be written to the Trigger file The Trigger file can be written using the falling edge the rising edge or using the camera output on the Inertial or a combination of all three EJ Oxford Technical Solutions RT Post process User Manual QOoxrs Finish page The Finish page gives the option to open the directory where the output file was written after the wizard closes Check the Launch Explorer on Completion to open the folder when Finish is pressed Revision 111102 a Vaxrs Requirements for Combined forwards backwards processing When processing backwards there are some tips needed in order to get the best results Many files will process backwards correctly but some will not Here is a list of things that can improve the processing or stop it from working A file that ends in a garage can cause prob
42. xample if data should be skipped at the start of the file etc The Output Configuration page is shown in Figure 13 a Oxford Technical Solutions RT Post process User Manual QOoxrs Figure 13 Output Configuration page RT Post Process Wizard Set Conditions RT2000 Inertial Free ET Seconds to skip at start Y fo Measurement Duration in seconds oo In which units do you System wish to measure acceleration Step 7 of 9 Output data rate 100 Hz AEG Velocity Units km h Select Raw Data File Working Directory Distance Units metres Base Station Process Page Select Fields Choose configuration settings for output Acceleration Units ms v Time Reference Units GPS v Output File For invalid measurements Blank z Finish Page Confidenthy Accurately B a_E__a F Sees Dev ID 110713 14a0 lt Back i Cancel Write status value as Text The RD file may contain a lot of data and only a short section may be required The top two lines can be used to crop the file The first line selects where the output file will start Three options exist as listed in Table 2 Table 2 Output Conditions Start Time Condition Description Seconds to skip at start This is the number of seconds that should be skipped after the start of the NCOM file This will include any time when the RT was not initialised Start Time hh mm ss This is the start time of the day in the Time Re
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