GPS Lap Timing
In circuit racing nowadays a GPS unit can be a cost effective alternative to the traditional lap timing system. The position of the start/finish line can be marked either by a push button operated by the driver when passing the line or by entering the coordinates directly into the data acquisition system. This position can then be used by the logger or display as a beacon to calculate the lap time and by the data analysis software to indicate the start of each lap.
Traditional Lap Timing System
MoTeC's lap timing system consists of one or more Beacon Transmitters (BTX) mounted beside the track and a Beacon Receiver (BR2) fitted in the vehicle. The Beacon Receiver is connected to a MoTeC display, data logger or ECU.
The lap timing system marks the beginning and end of each lap in order to record and display lap times and lap numbers. If several Beacon Transmitters are mounted around the track it can also generate split times. This information can be used by the data system for calculations such as lap gain/loss, where the current lap times and split times are compared to a reference lap. This can indicate to the driver whether they are faster or slower than before.
Code Numbering System
Each beacon transmitter is configured to a particular code number by a set of 3 internal rotary switches. The BR2 receives all BTX signals and sends them over CAN to the data logger, which is then programmed to look for a particular beacon number as its main or ‘lap’ beacon. Other beacon IDs can then be ignored or used as split beacons depending on the configuration. This allows for use of multiple transmitters at a track without interference (if each team has a BTX).
The Beacon Receiver will only pick up the Beacon Transmitter with the matching code number and will ignore all other transmitters. Theses code numbers are programmable, allowing one transmitter to be set up as a master beacon for all MoTeC customers at a particular race meeting.