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02 - VBOX LapTimer - GPS

Obtaining the best GPS quality

Placement of the GPS antenna is crucial to the quality of the data recorded by VBOX LapTimer. Any metal close to a GPS antenna can disturb the signal in an unpredictable way due to interference from reflections of weak GPS signals.

For the best results, use the antenna in the centre of a metal roof away from any roof bars or radio antennas. Do not mount the antenna close to the edge of the roof as reflections from the ground may interfere with the signals. Avoid the edges as reflections from the A-pillars will cause problems.

Mount the antenna as high up as possible and keep above any roll bars. Pieces of metal close to and above an antenna will badly disrupt the GPS signal.

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If the vehicle being used does not have a metal roof, then place the GPS antenna on a flat piece of metal at least 10cm in diameter. If this is not possible, copper or aluminium foil can be used to create a shaped ground plane underneath the antenna. For example, on a fibreglass roof, mount the antenna on top of the roof, and 

place some adhesive backed metal foil underneath, on the inside of the roof.

 

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Acquiring Satellite Lock

Tall buildings or trees can block GPS signals, causing a reduction in the number and quality of satellites being tracked, leading to inaccurate position measurements and a noisy velocity signal.

 

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GPS works best in open areas                                                        Avoid tree lined roads

 

GPS Coldstart

If VBOX LapTimer 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 cold-start, select MENU > GPS OPTIONS > COLDSTART.

Note: The GPS Options menu cannot be accessed when the LapTimer is being used in OLED mode. In this instance, the coldstart must be done on the connected unit.  

 

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Last modified
11:52, 11 Jan 2017

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