I have been following discussions about the use of goal-line technology in football.
A Special Meeting of the International Football Association Board (IFAB) on 5 July 2012 had goal-line technology as the first item on its agenda.
An IFAB report of the meeting noted:
Following the conclusion of a nine-month test process that began in August 2011, led by EMPA (Swiss Federal Laboratories for Materials Science and Technology), the IFAB unanimously decided to approve in principle both companies that took part in Test Phase 2: GoalRef and Hawk-Eye. This approval is subject to a final installation test at each stadium before the systems can be used in “real” football matches, in accordance with the FIFA Quality Programme for GLT.
The IFAB noted that the technology will be utilised only for the goal line. Revisions to the wording of specific Laws of the Game will be made, relating to: Law 1 (The Field of Play); Law 2 (The Ball); Law 5 (The Referee); and Law 10 (The Method of Scoring).
These are the goal-line technology specifications that guided the IFAB discussion of the technology.
Edgar Alvarez points out that:
GoalRef uses “electromagnetic antennas around the goal posts and crossbar to transmit a signal to a referee’s watch as soon as the entire ball crosses the line”.
Hawk-Eye “requires six to eight high-speed cameras — that shoot at 500 fps — to grab multiple images of the match ball and quickly process them to identify if it indeed crossed the line completely — this is also helped by black-colored dots on each goal post which aid the cameras gain a better overall precision”.
A second item on the agenda considered additional assistant referees (AAR) following a two-year experiment in the UEFA Champions League, Europa League and EURO 2012, as well as the AFC President’s Cup and competitions in Brazil, France, Morocco and Qatar. The IFAB agreed unanimously that the use of two additional assistant referees be approved. An amendment will be made to the Laws of the Game, “with a separate section concerning additional assistant referees. It was also approved that communication equipment be permitted between match officials in the Laws of the Game“.