In order to receive DGNSS corrections from the Base Station, the VBOX will need to be connected to a Racelogic telemetry modem that matches the type used in the Base Station setup. Example connections for VBOX 3i and VBOX II are as follows.
VBOX receives RTCM correction data from radio module. The radio module acts as receiver for information transmitted by Racelogic DGNSS Base Station. Racelogic also provide solutions to use SATEL radio modems for long range applications on large test sites. The connection to the VBOX will be the same in this instance, but an RLCAB096L would be used which has a 15 way D-Sub connector for connection to the SATEL radio modem.
Example of Local DGNSS Operation With VBOX 3i
Example of Local DGNSS Operation With VBOX Touch RTK
Example of Local DGNSS Operation With VBOX II
In addition to connecting the radio modem to the VBOX, it is also necessary to inform the GNSS engine that it must use the correction data in its calculations.
VBOX Setup software has options to enable the DGNSS corrections in any VBOX II, VBOX III, VBOX 3i or VBOX 3iSR connected to it. The mode selection will be chosen to reflect the Base Station mode that is being used, and the baud rate to reflect the type of radio modems and data baud rate being used. If your VBOX is not enabled for RTK (2 cm) or 20 cm then this will not work and an error message will confirm this. Once configured, you can then close the software program before disconnecting the VBOX.
To enable DGPS in a VBOX II, VBOX III or VBOX 3i, simply run the VBOX Setup software and select the COM port that the VBOX is connected to. VBOX Setup then automatically connects to the selected device.
The software will take a few seconds to communicate with the VBOX and open the VBOX Setup screen shown on the right. Once this appears, click on ‘GPS’, and then on the 'Settings' tab set the correct DGPS ‘Mode’ and ‘RS232 baud rate’ shown in the area highlighted red.
A VBOX Manager can also be used with VBOX II, VBOX III, VBOX 3i or VBOX 3iSR to enable the correct DGNSS mode. Within the menu, enter 'SETUP', select 'VBOX' and then 'DGPS MODE'. Select the correct DGPS mode from the available options. Select 'BACK' and then select 'DGPS RS232 RATE' within the 'VBOX' menu. Choose the correct DGPS baud rate and select 'EXIT' to return to main menu.
VBOX Touch RTK
VBOX Touch RTK is pre-configured to receive serial RTK correction messages, however the GNSS receiver settings can be changed using the touch screen if required.
If you would like to change the settings, ensure the unit is powered, press the Settings Button , choose the Serial Port Settings and then navigate to 'RTK Input'.
Ensure NTRIP Mode is 'Disabled' and then select the correct baud rate, this setting should be either 115200 kbit/s for a Racelogic blue boxed radio or 38400 kbit/s for a Satel grey boxed radio. Tap the buttons to change the settings.
It is also possible to change the 3rd tracked constellation between Beidou and Glonass if required by navigating to 'GNSS Selection' within the 'General Settings' screen. More information on this is available here.
Checking You Have DGNSS Lock
VBOX Test Suite
Can be used with any connected VBOX II, VBOX III, VBOX 3i or VBOX 3iSR.
|DGNSS (inc RTCMv2 40 cm) fix|
|Receiving data but not yet fixed|
|2 cm RTK fix|
|GNSS receiver position is fixed/locked|
|Position is being computed from the Kalman filter as GNSS is lost|
From approximately July 2004, all VBOX units have been shipped with DGNSS reception enabled. However, VBOX units supplied before this date will require a small hardware modification to be carried out by Racelogic to accept the DGNSS information via the radio modem. Please contact Racelogic for more information.
VBOX Touch RTK1
The status of the DGNSS lock within a VBOX Touch RTK can be seen on screen via the Satellite Icon.
|Flashing Red - No satellite lock||Solid Green - Standalone positional accuracy; Code Diff/SBAS positional accuracy|
|Solid Orange - RTK Float||Solid Purple - RTK Fixed|
The status is also available within the GPS Status area of the Diagnostics menu.
- SEARCHING FOR SATELLITES: The unit is searching for a valid satellite lock.
- STANDALONE: Position computed from GNSS only.
- CODE DIFF: Position computed from assisted SBAS corrections.
- RTK FLOAT: Position computed from GNSS corrected by RTK. Float means the GNSS receiver is still calculating the integer ambiguity, a small error will be present on the position computation at this time.
- RTK FIXED: Position computed from GNSS corrected by RTK. Fixed means the integer ambiguity is established and the optimum position correction is applied resulting sub 2 cm relative accuracy in good conditions.