Creating A Circuit Overlay; Aligning Circuit Overlays And Laps - Racelogic DriftBox Instruction Manual

Racelogic Ltd

Creating a Circuit Overlay

A circuit overlay is a file created to map the outer and inner bounds of a circuit.
Note: It is best to use an external aerial to get maximum position accuracy
• Power up DriftBox and let it acquire satellites for at least 5 minutes.
• Drive to the left hand side of the start of the circuit.
• Place the antenna on the left hand side of the roof.
• Insert the SD card, ready for logging.
• Drive round the left hand side of the circuit.
• Stop back at the place you started.
• Move the aerial from the left hand side of the roof to the right hand side slowly,
being careful not to cover the aerial – let it see the sky at all times.
• Drive at right angles across the track to the opposite side.
• Drive round the right hand side of the circuit.
• Load the logged file from the SD card using 'File' -> 'Load All'
• Save using 'Save', select 'Save as type' and pick 'Circuit file' ('.cir').
The .cir file can be now be loaded into the Graph screen and viewed in the Map window:

Aligning Circuit Overlays and Laps

The standard positional accuracy of DriftBox is 3M 95% CEP for Longitude and Latitude.
CEP = circle error probable.
95% CEP means 95% of the time the position readings will be within a 3M diameter circle
of the true position. This error is due to the changing state of the ionosphere, constantly
changing the time taken for the satellite signals to reach the earth.
This means that overlaid laps may appear to miss the edges of the track, especially if the
laps or overlay were logged several hours apart. In order to be able to view true drive
lines, right-click on the Graph Map. The option to align either the lap data or overlay
appears – using the keyboard cursor keys the runs can be correctly aligned.
DriftBoxTools Software
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