This article describes how to mix gx/ix and receiver mode on old versions of the firmware which do not have this functionality built in. In new firmware (starting 1803xx/1804xx) mixing the 2 modes is a feature of the firmware enabled through configuration (in current revision by -auto_control_on) and should be used instead of the method presented below.
Currently, GNSS control receiver and gx/ix modes are mutually exclusive (NAVconfig 170712am or earlier). For advanced users the settings can be changed to mix gx/ix and receiver modes on position and velocity. Generally, gx/ix velocity is better than receiver's provided that the raw data rate is high enough for the test (e.g., at least 4 Hz). At the same time currently receiver's position RTK mode is present more frequently than gxInteger, as the receiver uses GLONASS satellites as well. This guide shows how to configure gx/ix velocity and receiver position mixed mode.
Fig 1. GNSS configuration in NAVconfig.
Instructions to set gx/ix velocity and receiver position modes:
- Configure the system in gx/ix mode (see Fig 1.) and save the configuration in a folder.
- Open the main configuration file mobile.cfg previously saved and edit it.
- Locate the gx/ix configuration section, see Fig 2. The setting is off for receiver (rcv) position and velocity, on for gx/ix position and velocity, and enables ix (gpsrng_mode/gpsdop_mode).
- Modify the gx/ix settings: enable receiver position and disable gx/ix position as shown in Fig 3.
- Optional: increase the raw data rate o 4 Hz. This will be needed on RT3000/4000 systems where the raw data rate is only 2 Hz. All other systems have raw data rate of at least 4 Hz and this step is not needed. Locate the GNSS primary receiver configuration line and change the period from 0.5 seconds (Fig 4.) to 0.25 seconds (Fig 5.).
- Upload mobile.cfg file to the unit using FTP (make sure the new file replaces the file existent on the unit).
Fig 2. Gx/ix setting in mobile.cfg.
Fig 3. Edited file with receiver position and gx/ix velocity.
Fig 4. Raw data rate for GPS1 is 2 Hz (0.5 seconds).
Fig 5. Raw data rate for GPS1 is 4 Hz (0.25 seconds).
Reverting back the changes
The best way to make sure that the changes have been reverted back is to open the mobile.cfg file, locate the GNSS configuration settings and change them fully to gx/ix or receiver mode. In receiver mode the configuration is shown in Fig 6, in gx/ix in Fig 2.
Fig 6. Configuration for receiver mode
NAVconfig may also be used to change the settings but its behaviour cannot be guaranteed in the future revisions of the siftware. Currently the mixed mode is not a valid state for NAVconfig, therefore any configuration exported by NAVconfig will be either fully in receiver mode or in gx/ix mode. The current version (170712.14am) interprets the mixed mode from Fig 3 as receiver mode, so the file is back written in fully receiver mode (as in Fig 6). Alternatively, gx/ix can be selected from NAVconfig and the file will be configured as fully gx/ix mode (as in Fig 2.). Future versions of NAVconfig may be able to work with mixed modes and preserve the mixed setting.
If the data rate has been changed as well, NAVconfig interprets the new line (Fig 5) as an advanced option and when saving the configuration will add standard configuration (2 Hz, Fig 4) and the 4 Hz configuration as Advanced Setting at the end of the file, see Fig 7. The 4 Hz setting takes priority because it appears later on in the file. To revert it back using the text editor, change the period from 0.25 to 0.5. To revert it back to 2 Hz using NAVconfig delete the option from NAVconfig->Options->Advanced.
Fig 7. The 4 Hz raw GNSS data logging shown as Advanced Setting by NAVconfig.
If using NAVconfig with a mixed configuration it is recommended to save the configuration in a folder, open mobile.cfg and confirm the desired configuration.
- Testing the configuration can be done based on the position/velocity status modes in NAVdisplay/NAVgraph. Fig 8 shows the effect of configuring receiver position and gx/ix velocity.
Fig 8. Mixed mode navigation.
- Navconfig does not recognize the mixed mode and any file saved with the current revision of NAVconfig (170712.14am) will either be in gx/ix or receiver mode. This may change in future NAVconfig revisions.
- When post-processing data with RT Post Process and adding RINEX files, RT Post Process overrides the GNSS modes to fully gx/ix.