Sources block

Description

The source block lets you manually select, for each input which channel should be selected such as GNSS1/GNSS2 and also specify/override from which files data should be imported.

The following data inputs are supported by Qinertia:

• IMU data
• PVT trajectory data
• RAW GNSS data
• GNSS differential corrections (RTCM)
• HDT true heading data
• Odometer velocity data
• DVL water velocity data
• Event markers

Please read the Input formats to get more details about supported files format.

Files selection

If you have specified a project to import in the Project block, Qinertia will try to read all inputs from it. However, for each input, the sources block lets you list the files to import data from. You can thus easily override, for a  specific input, the Project block settings with a list of files.

If no project has been defined in the Project block, you have to list from which files Qinertia should read the data and this for each input you would like to use in the processing. The files have to be contiguous and should share the same mission/time interval. Qinertia will detect automatically the input file format to make sure it's consistent with the input data type.

You can safely list the same files for different data inputs if you would like to extract, for example, IMU and RAW GNSS data from files containing both.

Channel selection

Some input files can contain more than one data type. For example, SBG Systems INS can have up to two GNSS receivers and both receivers measurements are stored in a single binary sbgECom file. You should thus tell Qinertia if it should import data from the GNSS 1 or the GNSS 2.

You can even decide to completely discard a type of data and, for example, set the odometer.channel parameter to none.

JSON Block Sample

Import Project

In this example, an input project has been setup in the Project block and Qinertia will try to load all available data type from it. For instance, the IMU data will be loaded from it as well as the real time GNSS 1 PVT trajectory.

However, we explicitly tell Qinertia to load true heading data (hdt) from the GNSS 2 and not the default GNSS 1 and to ignore any available DVL data.

We also override the GNSS raw data and instead of using the data present in the input project, we load a RINEX file from an other GNSS receiver.

"sources": {
  "rawGnss": {
    "files": ["rover/rinexData.20O"]
  },
  "hdt": {
    "channel": "gps2"
  },
  "dvl": {
    "channel": "none"
  }
}

Empty/manual project

This is a typical example to support a third party IMU that is using generic files format. No input project has been specified in the Project block so each data type has to be set manually in the source block.

The following JSON asks Qinertia to import IMU from an ASCII file, RAW GNSS data from a Septentrio GNSS receiver using the binary sbf file format and input event markers from a simple CSV like text file.

"sources": {
  "imu": {
    "files": ["imu/imuData.txt"]
  },
  "rawGnss": {
    "files": ["rover/gnssRaw.sbf"]
  },
  "events": {
    "files": ["lidarEvents.txt"]
  }
}

Block Specification

Please find below the list of all available inputs supported by Qinertia. No input is mandatory to create a project as it depends on the processing modes you would like to use:

• GNSS only, requires rawGnss data and optionally events
• INS Tightly coupling, requires IMU and rawGnss data, all other inputs are optionals
• INS Loosely coupling, requires IMU and pvt trajectory information, all other inputs are options.

Parameter	Type	Optional	Description
imu	object		IMU data source configuration. See below for object details.
pvt	object		Trajectory data source configuration. See below for object details.
rawGnss	object		GNSS raw data source configuration. See below for object details.
hdt	object		True Heading data source configuration. See below for object details.
odometer	object		Odometer data source configuration. See below for object details.
dvl	object		DVL data source configuration. See below for object details.
events	object		Events data source configuration. See below for object details.
diffCorrStream	object		RTCM corrections received in real time data source configuration. See below for object details.

If you have not specified an input project in the Project block, you should specify in each data source you need the list of files to import.

Data source block

Parameter	Type	Optional	Description
files	array		Optional array of files to import. Those files will override any input project that could have been configured in the Project block.
channel	string		Channel to import within the file. The list of choices depends on the data and input file type. The option none is always available to completely discard a data type. Please see channel values to get other possible values.

Contiguous files

If you specify more than one file, please make sure they are contiguous and correctly ordered from oldest to newest.

Relative Paths

Relative paths are referenced to the JSON process file unless you have specified a base path with the --input option while invoking Qinertia command line.

Available Channel Values

The list of available values for the channel parameter depends on the data type and the selected input file format.

sbgECom files

SBG Systems products support up to two GNSS receivers and the channel parameter can be used to either import data from the GNSS 1 or the GNSS 2.

The following channel options are applicable to the PVT, HDT and RAW GNSS data types.

Septentrio files

Septentrio INS products are using sbf binary files format. It can contain IMU data for serial port.

The following channel options are only applicable to the IMU data type.