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RACELOGIC Support Centre

06 - VB3iS DGNSS / RTK Modes

For more information on what DGNSS is and how it works, click here. For more information on RTK, click here.

VB3iS supports an RTK connection using NTRIP. For more information on how this is set up, click here.

How to enable DGNSS Modes

VB3iS must have the correct DGNSS mode enabled via the VBOX Setup Software, the Front Panel of the unit or using the VBOX Manager before it is capable of receiving and using the DGNSS correction information transmitted by a Local Base Station or NTRIP service.


Available modes:

  • SBAS - SBAS differential corrections are received from the nearest Geo-stationary SBAS satellite.
  • RTCM - RTCM corrections are received by the VB3i via a Racelogic telemetry module and a locally placed Base station. Contact Racelogic or your local agent for more details.
  • CMR - 2 cm correction (Trimble standard message type).
    Only selectable with VB3iSR RTK variant.
  • RTCM v3 - 2 cm correction (RTCM standard message type).
    Only selectable with VB3iSR RTK variant.
  • MB Rover - Mode for use in Moving Base ADAS applications.
    Only selectable with VB3iSR RTK variant.
  • MB Base - Mode for use in Moving Base ADAS applications.
    Only selectable with VB3iSR RTK variant.
  • NTRIP - Internet based subscription service, more information on this can be found here.
    Only selectable with VB3iSR RTK variant.

VBOX Setup

  1. Ensure VB3iS is powered.
  2. Connect VB3iS to a computer using the supplied loom, connect the serial plug labelled 'Config' to the computer's serial port, this can be done via a serial > USB convertor if required.
  3. Open VBOX Setup and connect to VB3iS by selecting the correct COM Port.
  4. Select the 'GNSS' menu and then the 'Settings' tab.
  5. Choose the desired DGPS Mode and RS232 baud rate settings from the 'DGPS' options.
     

VB3iS GNSS VBS.png
 

  1. Select 'Write to unit' to save the settings.

Front Panel

  1. Press the 'OK' button to enter the menu, navigate to 'GNSS' and press the 'OK' button.
VB3iS Coldstart Front Panel1.png  
  1. Navigate to 'DGNSS Mode' using the 'Up' and 'Down' arrows. It will display whichever mode has been previously set.
VB3iS Dynamic Modes 1.png VB3iS DGPS Rate5.png
  1. If you would like to change the setting, press the 'OK' button then select the desired option using the 'Up' and 'Down' arrows.
VB3iS DGPS Rate6.png VB3iS DGPS Rate7.png
  1. Press the 'OK' button again to confirm.
VB3iS DGPS Rate8.png  
 
  1. Navigate to 'DGNSS Rate' using the 'Up' and 'Down' arrows. It will display whichever mode has been previously set.
VB3iS DGPS Rate1.png  
  1. If you would like to change the setting, press the 'OK' button then select the desired option using the 'Up' and 'Down' arrows.
VB3iS DGPS Rate2.png VB3iS DGPS Rate3.png
  1. Press the 'OK' button again to confirm.
VB3iS DGPS Rate4.png  
 

Using with Local DGNSS Base Station

When VB3iS is used in conjunction with a local DGNSS Base Station, the positional accuracy can be improved from the standard 3 m 95 % CEP.

There are two available Base Station options:

40 cm positional accuracy:

If VB3iS/VB3iSR is used with an RTCM-V2 enabled Base Station, then the positional accuracy is increased to 40 cm 95 % CEP. The height accuracy is improved to 1 m 95 % CEP.

2 cm positional accuracy:

If VB3iSR is used with an RLVBBS4RG or RLVBBS5 Base Station, then the positional accuracy is increased to 2 cm.

  • CMR 2 cm correction (Trimble standard message type).
  • RTCMv3 2 cm correction (RTCM standard message type) RECOMMENDED.
     

RTCMv3 is recommended as the default RTK 2 cm correction type. This message format is a globally recognised type and more resilient to data loss caused by radio errors.

Solution type lookup table

Solution Type  Definition
0 None
1 GNSS only
2 GNSS DGNSS (inc RTCMv2 40 cm)
3 RTK Float 
4 RTK Fixed
5 Fixed position
6 IMU Coast (Kalman Filter)

0 = None

GNSS receiver cannot compute a solution for position.

1 = GNSS only

Position computed from GNSS only.

2 = GNSS DGNSS

Position computed from assisted GNSS, this includes SBAS and Base Station DGNSS corrections.

3 = 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.  

4 = 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. The maximum period of time that the unit will remain in an RTK fixed state after it last received a valid RTK correction message is 15 seconds. After this time, the unit will revert to an RTK Float status.

5 = Fixed position

GNSS receiver position is fixed/locked. This is primarily used for base station receivers.

6 = IMU Coast

Position computed from the Kalman filter when GNSS is lost, inertial data from the IMU is used to maintain a solution for position until the GNSS is re-established. This solution type can be maintained for a maximum time of 600 seconds (10 minutes) when using Wheel Speeds, or 120 seconds (2 minutes) without wheel speeds, after which the solution type will change to 0.

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