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What are the additional files that are created when post-processing?

There are many different files that are used while post-processing. The input to post-processing is the RD file. The RD file has raw GPS and raw inertial measurements in it. The post-processing software blends the GPS and inertial measurements together and outputs an NCOM file. Then the post-processing software will convert the NCOM file to CSV, or the NCOM file can be loaded in to RT-View.

There are other files that the post-processing software creates when it is blending the GPS and inertial data. Most of these files are used to verify the algorithms and debug the data. We use them a lot at OxTS to check customer’s data, improve configurations and get better results.

Here is a list of the files and their functions. The file names assume that the RD file is called “mobile.rd”; any file that starts with “mobile” will be named differently if the RD file has a different name.

File Description
mobile.acr This file gives accuracy information in the vehicle co-ordinate frame (apart from the inertial sensor information, which will be in the IMU frame)
mobile.acy This file gives accuracy information in the IMU frame. This is used for algorithm debugging; it is easier to use the mobile.acr file for most applications.
mobile.ata This is an input file, it specifies the accuracy of the dual-antenna angles compared to the RT.
mobile.att This is an input file, it specifies the angles of the dual-antenna system compared to the RT.
mobile.cfg This is an input file, it is the main configuration file for the post-processing software.
mobile.gap This is an input file, it specifies the position of the primary GPS antenna compared to the IMU. It is in the IMU reference frame.
mobile.gpa This is an input file, it specifies the accuracy of the measurements in the mobile.gap file. It is in the IMU reference frame.
mobile.ncom This is the main output file for the post-processing software. It can be converted to CSV format using the post-processing software. It can be loaded in to RT-View. There are C-code drivers to interpret the file. There is a document describing the file format and the data in it.
mobile.nsa This is an input file, it specifies the accuracy of the data in the mobile.nsp file.
mobile.nsp This is an input file, it specifies the position of the non-slip point for Advanced Slip.
mobile.prn This is an output file from the post-processing software. It is a text based format. The inertial measurements are in the IMU frame. It is easier to use the mobile.rot format, where the measurements are in the vehicle frame. The file format is described below.
mobile.qcf This is an output file. It lists all the Quick Config commands that were sent to the RT in real-time.
mobile.rot This is an output file from the post-processing software. It is a text based format. The inertial measurements are in the vehicle frame. The file format is described below.
mobile.vaa This is an input file, it specifies the accuracy of the measurements in the mobile.vat file.
mobile.vat This is an input file, it specifies the mounting angles of the IMU in the vehicle.
result.* These files are produced by the post-processing software. They are calibration information for bootstrapping the post-processing. After post-processing once, these files can be renamed from result.* to mobile.* (or whatever name the RD file has), then the post-processing software can be re-run. It will improve the accuracy of the post-processing, particularly in the warm-up period. The improvement is marginal and we do not normally use it in the office.

 

Format of the mobile.prn and mobile.rot files

These files are in text format, space separated between the columns. Each row represents a different time epoch. The columns are:

Column

Description

1

GPS Week (Weeks since 6th January 1980)

2

GPS Time (seconds since midnight Sunday)

3

Latitude (degrees)

4

Longitude (degrees)

5

Altitude (m)

6

North Velocity (m/s)

7

East Velocity (m/s)

8

Down Velocity (m/s)

9

X-Acceleration (m/s2, IMU frame or vehicle frame)

10

X-Acceleration (m/s2, IMU frame or vehicle frame)

11

Y-Acceleration (m/s2, IMU frame or vehicle frame)

12

Z-Accelerations (m/s2, IMU frame or vehicle frame)

13

Heading (degrees)

14

Pitch (degrees)

15

Roll (degrees)

16

X-Angular Rate (deg/s, IMU frame or vehicle frame)

17

Y-Angular Rate (deg/s, IMU frame or vehicle frame)

18

Z-Angular Rate (deg/s, IMU frame or vehicle frame)

These are the basic measurements that the RT outputs. All the other measurements can be derived from these measurements using suitable transforms and rotations.

Note: This FAQ was created on 28/11/08 and is not kept up to date. If you find some of the information is out of date then please email support and we will let you have the latest information.

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