This guide will outline the general work flow of post processing your data using OxTS's processing engine wizard, RT Post Process. Topics covered in this guide will include:
- Arranging the files properly for processing
- Using a base station file with your data set
- Exporting data in the format you require
2. Preparing for processing
2.1 Getting the files off your system
All the data that you have recorded during your measurement is stored on the system's own internal storage. Getting those files off your system is as simple as typing the IP address of the system into a windows explorer address bar. A typical explorer window of a system should look similar to this is:
- The files ending with .rd are the raw data files that contain a variety of information including configuration, raw GNSS information etc.
- They are tagged with the GPS time and date at the start of measurement for easy reference.
- You can drag these files off to your working folder for processing
All the other files contain the last known configuration sent to the system.
2.2 Preparing your folders for processing
Post processing a single file can generate a large number of output files so it is recommended to create folder with the name of the rd file and process within it, to avoid confusion and conflicts when processing the data.
3. Processing the rd file
In order to process the files, you need to have the latest version of NAVsuite installed. You can find it at this link: http://www.oxts.com/software/NAVsetup.zip.
RT-Post Process will then automatically associate itself with your .rd files.
3.1 Options to start the process
Once installed you have several options to process your data:
1) Double click RD file…
This will open your file ready to be processed
2) Open the post-process wizard directly…
whilst connected to the RT,
Direct the wizard to your RD file
Direct the wizard to an NCOM file (for CSV output) skip to step 5 if using this option
3.2 Set your working directory
- Choose the folder you want to extract configuration files to and the location of your soon to be processed files. Remember to extract these configuration files, otherwise the system will not have the information regarding your particular set-up:
3.3 If using a base station to supply RINEX corrections (skip this step if no base station was used)
- Select the corrections file from your working directory
- These will either be downloaded from a local service, or logged in real-time
- For RINEX files only the observation file is needed for most systems (the .**o file)
- More detail on processing with a RINEX file can be found here
3.4 Processing tab options
- Choose whether to process using one of two options:
3.4.1 Simulated (real time) recreate the behaviour of the system in real-time
- Good for diagnosis analysis and good GNSS environment conditions
3.4.2 Combined (forwards/backwards) - blends two results to crate the best output
- Good for bad GNSS environments and optimum performance
- This option should be used with good initialisations, at both the beginning and end of testing, as bad initialisation at either end may output bad results, in comparison to the simulated (real-time) option.
For example: At the end of a testing session, a driver parks their car in a garage and GPS signal is lost, but the device is still on for a reasonable amount of time until they power off the device. As a result, the measurements drift off due to no GPS signal to correct it. Now once the combined processing algorithm begins the backwards calculations, it skips much of the data and results in the algorithm taking an unsuitable point for initialisation, thus producing a bad output. This is due to the algorithm taking an average of selected points from both the forward and backward files, as illustrated below
You must avoid this problem by driving in a straight line before turning the device off and entering any garage or any area that may cause drifts, at the end of your testing as shown
3.4.3 Choose additional options
- Output MCOM file – outputs an NCOM file with additional “Heave” measurement for marine use
- Clean-up directory after processing – remove all files created during processing apart from the resultant NCOM file. Uncheck this if you want to analyse individual processing results (i.e. forwards and backwards NCOM files)
- Display results in NAVgraph after processing – automatically open NAVgraph once processing is complete
- Enable advanced smoothing apply an additional filter the the combined processed data, this will take longer but produce smoother results with less innovations.
3.5 NCOM file processing
Once processed, an NCOM file will be outputted and you have the following options:
- Select the variables you wish to output data for
You can use the post-process wizard to output the data to a file type for use with other software:
- Select the output variables for the file, like output rate, and units of measurement