ABOUT GOAL-LINE TECHNOLOGY

The International Football Association Board
requires that goal-line technology does not
interfere with the game, and as such only the
match officials receive a signal on their watches to
indicate whether the whole of the ball has crossed
the goal line.
This information is transmitted within one second,
which ensures an immediate response from the
referee and that there are no stoppages or other
forms of interference in the game. The match
officials are the only ones to receive a signal.
Unless the competition organiser decides to show
a replay, this information is only available to the
match officials.

The Principles of the Goal-Line Technology system

Camera-based:

Several approved systems work with cameras that
detect the ball and use software to evaluate the
footage from all the cameras. In this way, the
system can determine whether the whole of the
ball has crossed the goal line. Currently licensed
systems work with seven cameras per goal
installed as high up as possible within the stadium
structure.

Magnetic fields:

Several systems operate with magnetic fields. For
these systems, cables are placed underground and
around the goal, and the ball has elements of the
technology inside. The interaction between the
receptors in the ball and the magnetic fields
created through the underground cables allow the
software to calculate the exact position of the ball
and determine when a goal has been scored.