For Slip and Pitch measurements
Required equipment (All supplied as standard unless specified):
- Place VBOX in vehicle then mount the GPS/GLONASS antennas on the vehicle roof in-line with the direction of motion, and clear from any obstructions. Connect the primary antenna (normally at rear of vehicle) to 'Port A', and the secondary antenna to 'Port B' on the VB3iD/VB3iDR.
Note: It is important to connect the antennas to the VB3iD/VB3iDR before power is connected. The VB3iD/VB3iDR adjusts the signal gain to the antenna based on the current incoming GNSS signal strength.
See these articles if having difficulty obtaining satellite lock: Satellite elevation mask GNSS Cold start
- Note that any alignment error can be zeroed using the ‘ALIGN ANTENNAS’ option on VBOX Manager.
- Make sure the antennas are rotated so the wires exit in the same direction as each other.
- Accurately measure separation distance to the nearest 5 mm, for best accuracy measure from the point at which the cable exits the antenna.
- For normal operation, place the primary antenna (Port A) at the rear of the car, and the secondary antenna (Port B) at the front. All measurements are made from the primary antenna.
- Power up VB3iD/VB3iDR.
- Connect VBOX Manager to VB3iD/VB3iDR port dedicated to Racelogic CAN bus (determined in CAN tab of VBOX Setup).
- Go into SETUP>DUAL ANTENNA>SEPARATION and enter the separation of the antennas.
- Allow the unit time to acquire full satellite lock. The number of satellites in view is indicated by the ‘SATS’ LED; the total of green flashes indicates GPS count, whilst an orange flash indicates the GLONASS satellite count. If the VBOX has not been used for a long time, or the location where it is being tested has changed drastically, a GNSS coldstart may be required.
- Move forward in a straight line, in an open area, and the 'DUAL' LED should turn green to indicate dual antenna lock has been obtained. Once the 'DUAL' LED is lit (green) you are ready to begin testing.
Note: It takes around 30 – 60 seconds to reach full accuracy on the pitch measurement.
For Slip and Roll measurements
- Follow the same steps as ‘Slip & Pitch measurement’ guide, but mount the antennas 90° to the true heading of the vehicle such that the primary antenna (Port A) is on the left hand side of the roof. Minimum recommended separation between the antennas is 0.5 m on a level plane, but the greater the separation distance, the better the accuracy.
- Using VBOX Manager, go into SETUP>VBOX>DUAL ANTENNA and tick ‘ROLL MODE’.
- Go into SETUP>VBOX>DUAL ANTENNA>SEPARATION and enter the separation of the antennas.
- Try to avoid placing the antennas close to the edge of the roof as this may result in poor dual lock. This is because reflections from the ground will disturb the signals.
- Driving forward should now bring on the green 'DUAL' LED.
Note: If the IMU integration feature of the VBOX 3i is to be used refer to this article ‘IMU Integration’
Dual Antenna Placement
Careful attention must be paid to placement of the antennas.
It is essential that the separation of Antenna B from Antenna A is exactly the same as the separation value set inside the VBOX 3i via VBOX Manager, or within VBOX Setup. If the separation is incorrect, data may not be given or may be inaccurate.
Where possible, antennas should be placed on a level plane. The measured distance between the antennas should be the 2D distance between the antennas as viewed from above. It is not the straight-line distance between the antennas, regardless of the mounting angle.
The supplied tape measure will help ensure an accurate antenna separation.
Antenna A is the primary antenna, from which all calculations are based (unless using IMU Integration). Therefore the primary antenna should be placed relative to where you wish to make your measurements from. For example, If you wish to make measurements from the centre of the vehicle, this can be achieved by placing the primary antenna at the centre of the vehicle. You may also like to take slip measurements from other locations on the vehicle, for instance the centre of gravity or slip over the wheels. This can be set using the slip angle translation function in VBOX Manager.
Note: If you are using IMU integration, calculations will made from the antenna/ IMU offset.