There is currently no way of being completely sure. Which means that time and again a goal is wrongly allowed or disallowed. And as football fans know, even with hindsight it is often impossible to tell whether a goal should or should not have counted.
To help avoid incorrect goal decisions, Fraunhofer IIS has developed a radio-based system called GoalRef™. Using low-frequency magnetic fields, it reliably determines whether or not the whole ball has passed over the goal line.
GoalRef™ is a radio-based sensing system that uses low-frequency magnetic fields to detect if a goal has been scored.
FIFA’s Laws of the Game state that “a goal is scored when the whole of the ball passes over the goal line, between the goalposts and under the crossbar, provided that no infringement of the Laws of the Game has been committed previously by the team scoring the goal.” However, when it comes to deciding whether all of the ball was over all of the line, the naked eye can be inadequate. This is where GoalRef™ comes in.
The system uses low-frequency magnetic fields. One field is created in the goal area, the other is created in and around the ball whenever it approaches the goal. This is achieved through magnetic induction, which in turn is made possible by a passive electronic circuit embedded in the ball. The interaction between the main field around the goal and the field induced around the ball is picked up by coils attached to the goal.
By measuring and analysing changes in the magnetic field around the goal, it is possible to determine whether the ball has completely crossed the line. The data is processed using software developed by Fraunhofer IIS, yielding a clear, accurate result that removes any doubt about whether a goal has been scored.
The result is wirelessly transmitted to the referee’s wristwatch, and a message is displayed in real time, coupled with a vibrating alert. The information is encrypted to prevent eavesdropping or tampering.
“Products based on the GoalRef™ technology have enormous market potential. Apart from football, they can be used in other team sports at both professional and amateur levels”, says project leader Ingmar Bretz.
Following the go-ahead from FIFA, the system is to be gradually introduced in professional football leagues.