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 Apache,
as well as by Mikrofyn, 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.