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By Greg Bartlett

Time Speed Distance rallies are car races which are conducted on the open, public road. Usually there are many cars and they have to be started on a time delay, in a staggered fashion. These are very complicated races. The competitors, usually a driver and a navigator, have to follow instructions given out by the rally master. These instructions can be of the form: ‘drive in as straight a line as possible’ or, ‘turn right on the next road.’ The winner is the car who achieves the lowest score. That is, they follow all the instructions exactly and incur no points at all.

In the olden days, the winners were calculated using extremely old fashioned equipment such as maps and slide rules. Marshalls along the length of the track took time and location readings. These were conveyed to the race organizers. Later computers and calculators were used to work out who was the elusive zero-hero. Complex equations and calculations and expensive and delicate on board odometers were used.

A GPS tracking system is not only useful for finding the position of something, but also for tracking its movement across a certain distance. They work by using signals from satellites in space which transmit exact data at synchronized intervals. Because each satellite transmits the signal at exactly the same time, a receiver on Earth can judge its location by extrapolating differential information.

The Time Speed Distance rallies need to have absolutely accurate information to be useful in judging who has won. Each distance and time recorded must be precision correct. Arriving early is just as bad as if the drivers arrive late. Just such computations can be worked out using GPS tracking technology. Initial tests have been conducted to compare the tracking technology with data provided by the expensive on-board odometers. By conducting these tests it was hoped to examine whether GPS tracking can work out accurate enough data in real-time.

It has been found that both systems can provide incredibly accurate information which can be used to compare two cars and see which one has won the race. The only difference has been that the on board odometer is very expensive and does provide real-time information, but this all happens after the race has been run and computers are used to perform the calculations. Using real-time GPS technology, the winners can be decided seconds after the race has been run.