Carlson Field can use an external Light Bar for determining elevation
differences and centerline offsets. Light Bars can indicate whether your
current position is in cut, fill or on-grade when set vertically. When set
horizontally, Light Bars can give centerline left/right offsets. Currently
Carlson Field supports a light bar made by Mikrofyn named RD-4 1137551, as well as
by Apache, that has arrows for up/down, or left/right, and a row of lights
for on-grade. The Light Bar must be connected to a separate serial port
than the GPS.