‘C’mon! You can’t be serious?!’ How often have we heard this phrase in sport? Fortunately at the elite level of tennis, cricket and soccer, this expression is gradually being phased out thanks to patented technology.

One of the first and probably most widely adopted officiating aids is the versatile goal net, which was patented by John Alexander Brodie in 1890 (Patent application no. 19,112). The net was designed to help determine whether a ball had passed between two posts, in response to a disputed goal in a fiercely contested match

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between Everton and Accrington in 1889. Since 1890, goal line and ball tracking technology has become more sophisticated and numerous patents have been submitted which incorporate the use of electromagnetic sensors, signals, and high speed imaging.

However, it was not until approximately 10 years ago that these more sophisticated patented technologies have been used as officiating aids in elite sports, making the treasured sporting codes safer, and more engaging. These inventions have circumvented passionate disputes, and maintained a certain degree of world peace by giving us definitive answers to some very important questions such as ‘Was it in or out?’, ‘LBW?’ (Leg Before Wicket), and ‘Did it cross the line?’.

Current patented technologies

The Hawk-Eye System

(Patent no. WO200141884)

The ‘Hawk-Eye’ System is by far the most commonly used technology by broadcasters and officiators in elite sport. It commands the respect (and at times ire) of players, officials and crowds alike in cricket, tennis and soccer, amongst other codes. The system was developed by Dr Paul Hawkins, an avid cricket fan. It was originally designed to track and predict the trajectory of a cricket ball to analyse LBW decisions. 

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The ‘Hawk-Eye’ System is software that relies on the principle of triangulation using visual images and timing data provided by a number of high-speed video cameras placed at different locations around an area of play. Images are processed in real-time by a number of computers and sent to a central computer programmed to process and analyse the data according to set parameters relevant to the sporting code. In each camera frame, the system identifies the cluster of pixels that corresponds to the image of the ball, whereby only 25% of the ball needs to be visible. For each frame, the system calculates the threedimensional position of the ball by comparing the ball’s position at the same instant in time captured by the different cameras. A succession of frames builds up a record of the path along which the ball has travelled. Using this information, the system is able to track and predict the trajectory of a ball, even if the ball has hit an obstruction. The system is extraordinarily accurate and performs with an average error of 3.6mm!

GoalControl-4D (Patent no. WO2014059971)

Following a blatant mistake by the officiators at the 2010 FIFA World Cup, where England’s Frank Lampard was denied an obvious goal, FIFA decided to introduce goal line technology at the 2014 FIFA World Cup in Brazil. ‘GoalControl 4-D’ was installed in all World Cup stadiums.

The system is made up of 14 cameras placed around the rim of the stadium, and are positioned to focus on the goals. The cameras are connected to a powerful image processing computer system which tracks the movement of the ball by analysing triangulation data sent from the cameras which capture approximately 500 images per second. Once the ball has crossed the goal line, a vibration and signal is sent to the referee’s watch. The system has an accuracy of goal detection of up to 5 mm, which is much more accurate than a linesman standing approximately 25 metres away!

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Goalminder (Patent no. WO2012038746)

The ‘Goalminder’ system was developed by Harry Banes after seeing his beloved Bolton Wanderers relegated from the English Premier League because of a disputed goal. The system comprises fibre optic cameras built into the crossbar and posts of a goal, which record images at 2,000 frames per second to track the trajectory of the ball. When the ball crosses the line, the information collected by the cameras is processed by a computer which uses threedimensional imaging software to map the trajectory of the ball in real-time. Once the ball has crossed the goal line, the referee is sent a visual display confirming the goal.

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Cairos GLT system (Patent no. WO2008119479)

In its first foray into goal line technology, FIFA trialled the ‘Cairos GLT System’ at the 2005 Under-17 World Championship. The system involves embedding thin cables in the turf of the penalty area and behind the goal line. The electrical current that runs through the cables generates a magnetic field, which is divided up into grids. The ball incorporates a sensor which measures the magnetic grids and transmits data about the ball’s location. When the ball completely crosses the goal line, a radio

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signal is transmitted to the referee’s watch instantaneously. Despite being satisfied with the performance of this technology, FIFA decided against its use in subsequent tournaments, controversially insisting it was only ‘95% accurate’, and expressing concern that the chips in the ball may be displaced by the magnificent force exerted by a Cristiano Ronaldo kick!

GoalRef (Patent no. WO2009046722)

Similar to ‘Carios’, ‘GoalRef’ uses magnetic fields to detect if a goal has been scored. The system requires a weak magnetic field to be created at and behind the plane of the goal. In essence, this creates the radio equivalent of a light curtain at the goal. The strength is monitored by sensors linked to a computer. A weak magnetic field is also created around the ball through the use of a passive circuit embedded as an interior layer. When the ball completely penetrates the curtain, a change in the magnetic field is detected and the computer automatically sends a signal to the referee’s watch. Unlike the ‘Cairos’, the ball does not act as a sensor. The System has passed FIFA’s stringent testing criteria and has been approved for use at elite competition level.

Unfortunately, there’s still a long way to go before we see these exciting and innovative

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technologies used in semi-professional and amateur competitions, as the cost is somewhat prohibitive. Until then, we have to rely on the versatile goal net, the umpire and referees.