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RACELOGIC Support Centre

Quick Start - Speed Sensor Dual Antenna


For Slip and Pitch measurements

Required equipment (All supplied as standard unless specified):

  • VBSS100SL                                                                                         
  • Connecting Loom (RLCAB093-C)                                               
  • VBOX File Manager + RLCAB005-C
  • 2 x GPS & GLONASS antenna (RLACS156)
  • Tape measure
  1. The Speed Sensor unit needs to be mounted flat inside the test vehicle. Failing to do so will have an impact on the accuracy of the calculated slip channels.
  2. Mount the GPS/GLONASS antennas on the vehicle roof in-line with the direction of motion, and clear from any obstructions (see image below). For normal operation, place the primary antenna (Socket A) at the rear of the car, and the secondary antenna (Socket B) at the front. All measurements are made from the primary antenna.
  3. Make sure the antennas are rotated so the wires exit in the same direction as each other.
  4. Accurately measure separation distance to the nearest 5 millimetres, for best accuracy measure from the point at which the cable exits the antenna.
  5. Power up VBSS100SL.
  6. Connect VBOX Manager to VBSS100SL via Lemo CAN connector on RLCAB093-C.
  7. Through VBOX Manager, go into VBOX->DUAL ANTENNA->SEPARATION and enter the separation of the antennas.
  8. 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 Speed Sensor has not used for a long time, or the location where it is being tested has changed drastically, a GPS coldstart may be required. Note that VBOX Setup Software must be used to do this.

ant1 (1).jpg

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 0.5m on a level plane, but the greater the separation distance, the better the accuracy.


Using the VBOX Manager, go into VBOX->DUAL ANTENNA-> and tick ‘ROLL MODE’.

Go into 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.

In order to get a useful slip angle in Roll mode you will need to follow the slip translation guide. The slip angle is calculated from the primary antenna position which in roll mode is off-centre and will give inconsistent measurements. Translating this position back to the centre of the car will make the slip measurement consistent when turning both ways.

Antenna Placement

Whilst installation and use of the VBSS100SL is intended to be fast and simple, 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 Speed Sensor via the VBOX Manager, or  VBOX Setup Software. If the separation is incorrect, data may not be given or may be inaccurate. The measured distance between the antennas should be the straight-line distance between the antennas regardless of the mounting angle. It is not the 2D distance between the antennas as viewed from above.

The supplied tape measure will help ensure an accurate antenna separation.

Antenna A is the primary antenna, from which all calculations are based. 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 or translating the position using the slip angle translation function in the Vbox Manager.

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