VBOX Touch has the ability to conduct Accel and Decel performance tests. If you are conducting a test and the run gets aborted before the end conditions are met, the most likely cause is that a drop in satellites has invalidated that run.
VBOX Touch will only present accurate results rather than attempting predicting to predict data. So if VBOX Touch detects no satellite signal during a test run, that run will get aborted in order to provide only correct data. The data from before the run was aborted will still get recorded to the SD card for later analysis.
It is crucial to ensure that VBOX Touch is provided with the optimum conditions for recording data, please follow the guidance below to avoid performance tests from being aborted in the future.
Using Internal Antenna
VBOX Touch has an internal patch antenna, meaning that in many circumstances where the unit has a clear view of the sky, an additional antenna is not required. However, the satellite signals can be influenced from various factors.
The unit should be mounted on the windscreen in a suitable location and adjusted as necessary. Any potential interference from features such as roof bars and windscreen wipers should be minimised as much as possible.
Some modern cars are fitted with a special windscreen that cuts down the amount of UV (Ultra Violet) rays that will be transferred through the windscreen which help cut down on glare. These windscreens are called athermic, or UV Coated and will dampen/reduce GPS signals coming through the windscreen, so if you have an athermic windscreen, it means you will not receive the same quality of signal as you would do by taking the VBOX Touch outside of the car.
To tell if you have an athermic windscreen, you can either contact the manufacturer of your vehicle, or talk to the main authorised dealer who may be able to tell you. If you cannot receive a firm yes or no, then another way to check is to power up VBOX Touch and hold it outside of the vehicle, receive a satellite fix and use the Diagnostic Settings screen to see how many satellites you can see. Once you have noted this down, move the unit inside the car and see if the GNSS signal drops by 2-4 sats. If it does this immediately, then you probably have an athermic windscreen.
Using External Antenna (RLACS262)
If you are using an external antenna (RLACS262) and the unit is having trouble locking onto satellites, then please follow the checklist below for typical solutions.
Common problems with GNSS antennas is due to damage to the cable and the connector. The cable should be placed in a position that avoids tight angles being inflicted on the cable, as this can damage the thin core.
- Ensure that the antenna is placed in a position where it has an unobstructed view of the sky (see GNSS Antenna Placement below).
- Check the antenna connection with VBOX Touch; only small amounts of dirt in the socket can cause a significant reduction in signal strength. Also check the cable at the plug and along its length for any damage.
- If possible try another known working antenna, to confirm antenna functionality.
- Perform a GPS Coldstart and then leave the unit powered up in an open static position for at least 15 minutes.
GNSS Antenna Placement
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 GNSS antenna works best with a metal ground plane underneath, silver foil, or a metal plate beneath the antenna can improve reception significantly if you don’t have a large metal roof.
Click here for more information on antenna placement.
Tall buildings or trees can block GNSS signals, causing a reduction in the number and quality of satellites being tracked, leading to inaccurate position measurements and a noisy velocity signal.
GNSS works best in open areas/ Avoid tree lined roads
If VBOX Touch is struggling to acquire satellite lock, a GPS coldstart may be required. This may be necessary when the unit hasn’t been used for a number of days or has dramatically moved location since its last use.
To perform a coldstart, press the COLDSTART button within the Diagnostics Settings menu.
When the button has been pressed, the unit will make an audible sound and a ‘PLEASE WAIT’ message will be displayed on the screen which will count down from 3. The number of satellites will then be displayed as '00' and GPS status will show ‘SEARCHING FOR SATELLITES’ until satellite lock has been acquired. It will take approximately 25 – 30 seconds for the unit to reacquire satellite lock.