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RACELOGIC Support Centre

02 - VB3iS Antenna Placement

Introduction

The GNSS antenna supplied with VB3iS (RLACS156) is a 5 V active antenna. For the best possible signal quality, it is important to maintain a clean connection between the antenna and VB3iS. Before fixing the antenna to VB3iS, ensure that there are no dust particles in either connector. Replacement antennae are available by contacting your VBOX distributor.

The antenna is a magnetic mounting type for quick and simple mounting to the vehicle roof. For optimum GNSS signal reception, make sure that the antenna is fitted to the highest point of the vehicle away from any obstructions that may block satellite reception. The antenna works best with a metal ground plane underneath (a metallic vehicle roof is perfect for this).
 

setup1 (1).png
 

GNSS antennas require a ground plane to operate correctly. This helps to reduce unwanted reflections of the GNSS signal caused by nearby objects, and usually the metal roof of a vehicle performs this function. However, if a test requires an antenna to be placed either off the vehicle, or on a vehicle that does not have a metallic roof, a special ground plane antenna must be used. This has an internal ground plane and can operate perfectly without the need for mounting on a metal surface. Ground plane antennas are available from your VBOX distributor.
 

setup2 (1).png


Please also note that when using any GNSS equipment, a clear sky view is important. Objects in the surrounding area such as tall buildings or trees can block the signal causing a reduction in the number of satellites being tracked, or introducing reflected signals that can decrease the accuracy of the system. Note that clouds and other atmospheric conditions do not affect the VBOX’s performance.
 

setup3 (1).png
 

Satellite Elevation Mask

This feature can be used to improve GNSS signal quality when nearby obstacles like trees and building are reflecting or temporarily obscuring the signal from satellites at low elevation. Raising the mask will cause the GPS engine to ignore satellites below the mask angle, so must be used carefully as it also reduces the total number of received satellites.
 

sat_elevation_mask (1).png
 

The elevation mask value can be changed between 10 – 25° (10º by default) via the VBOX Setup Softwarethe Front Panel of the unit or using the VBOX Manager.

VBOX Setup Software

  1. Ensure VB3iS is powered.
  2. Connect VB3iS to a computer using the supplied loom, connect an RLCAB001 cable to the 'CONFIG' lead and connect the serial plug to the computers 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. Use the dropdown menu within the 'GNSS settings' options to choose the desired angle.
     

VB3iS VBOX Setup GPS Elevation Mask.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 'Elevation Mask' using the 'Down' arrow. It will display whichever mode has been previously set.
VB3iS Dynamic Modes 1.png VB3iS Elevation Mask 1.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 Elevation Mask 2.png VB3iS Elevation Mask 3.png
 
  1. Press the 'OK' button again to confirm.
VB3iS Elevation Mask 4.png  

GNSS Coldstart

A coldstart may be required when:

  • The GNSS engine has locked up
  • VB3iS is struggling to acquire satellite lock


A coldstart forces the GNSS engine to reset its downloaded almanac of current satellite positions. This can be useful if VB3iS is having trouble locking onto satellites, which typically occurs if the speed sensor has not been used for several weeks or if it was last used a long distance (over one thousand miles) away from the current location.
 

After performing a coldstart, leave VB3iS powered up in a static location where the antenna has an unobstructed view of the sky until the display reads 'OK'.

Once VB3iS has downloaded the new almanac, it will reacquire satellites in noisy situations (such as near trees, buildings and under bridges) much quicker. It will also acquire satellites much quicker on power-up.

The VB3iS can be coldstarted via the VBOX Setup Softwarethe Front Panel of the unit or using the VBOX Manager. All GNSS settings are retained after the process.

VBOX Setup Software

  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.
 
  1. Select 'GNSS coldstart' from the GPS information section.
     

VB3iS Coldstart VBS.png

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 'GNSS Coldstart' and press the 'OK' button. 'In Progress' will be displayed, showing that the coldstart has been performed and the GNSS engine is now not locked onto any satellites.
VB3iS Coldstart Front Panel2.png VB3iS Coldstart Front Panel3.png
  1. After approximately 30 – 45 seconds, the display will read 'OK'.
VB3iS Coldstart Front Panel4.png