One part of a data acquisition system is not located on the race car, but positioned trackside. As the race car passes the beacon, the data logger is signaled that a lap is completed and starts recording the next lap's data. Most systems can provide straightaway and corner segment times for each lap even though a single beacon is used. Typically, a motorcycle battery or regular car battery provides power for larger units such as this one. Lower speeds on short tracks may not require larger beacons, but if you run at Daytona, bigger is better.