How Does The Goal Line Technology Work?

By Matthew

30 December 2020 • 0:15GMT

 Since its introduction in the Premier League's 2013/14 season, Hawk-Eye's Goal Line Technology system has failed just once in over 9000 matches that it has been in operation. Of no doubt, the Goal Line Technology (GLT) has refined football, and so, how does it work?

GLT is basically a cluster of technologies that together monitors the path and movement of the ball and spots when it crosses the goal line. There are 4 major systems of the GLT approved by FIFA and the International Football Association Board (IFAB) which operate mainly by either camera tracking or magnetic field sensors.

•GoalControl

At the 2014 FIFA world cup, Brazil, GoalControl was the GLT system used. The German Company gained approval and certification just before the Hawk-Eye system. Before it was used at the world cup, it was successfully tested at the Confederations Cup and at the FIFA club world cup, 2013.

GoalControl uses camera tracking. 14 high speed cameras are mounted on the stadium roof (7 cameras per goal mouth) to capture the position of the ball in the air and on the ground. The referee receives a notification via his watch when the ball crosses the line.

•Hawk-Eye

Just like GoalControl, Hawk-Eye uses camera tracking. 7 cameras are installed at each goal, usually at the roof of the stadium. A software gathers the information from all cameras and then, tracks the ball in relation to the goal line. A signal is sent to the referee's watch within a second when the ball crosses the line. Ten seconds after, a graphical display of the ball's location is ready to be broadcasted.

Hawk-Eye is the present GLT system of the English Premier League and has been around since 2013.

Seven High Speed Cameras per goal mouth

•GoalRef

German Company, Fraunhofer IIS is the creator of GoalRef, a company that specialises in wireless communications. This GLT system uses magnetic field sensors built into the goal frames to detect the passing of the ball.

•Cairos GLT system

Cairos technologies and Adidas are the producers of this GLT system which also uses magnetic field sensors. In this system, a magnetic sensor is put into the ball. This sensor detects the magnetic field produced by thin wires underneath the penalty box. A computer then tracks the position of the ball using the sensor.

Another GLT system is GoalMinder which uses cameras built into goalposts and crossbars.

The Sheffield United Incident

A foul is being committed. It's a free kick to Sheffield on their left flank. Oliver Norwood is standing over the dead ball, ready to take the free kick and Aston Villa's defence is getting organised. Norwood sends a beautiful ball in, but Villa's goalie, Ørjan Nyland claims the ball in the air. As Nyland reaches for the ground, teammate, Keinan Davis bumps into him and then he is pushed together with the ball beyond the goal line. Nyland quickly presses the ball unto the goal frame, Sheffield United players are celebrating, the ball clearly crossed the line already.

Nyland is seen to have crossed the line with the ball. Photo Credit: Sheffield United TV

To their surprising disappointment, Referee, Michael Oliver doesn't award the goal, his wrist watch hasn't indicated, by vibration, that the ball crossed the line. Inevitably, this decision sparks a lot of controversies.

Hawk-Eye, the company that runs the league's goal line technology, after the match said that the view of the seven cameras were obstructed by the combination of the goalkeeper, defender and the post. Its statement read:

"During the first half of Aston Villa v Sheffield United match at Villa Park, there was a goal line incident where the ball was carried over the line by Aston Villa goalkeeper, No. 25 Nyland.

"The match officials did not receive a signal to the watch nor earpiece as per the Goal Decision System (GDS) protocol. The seven cameras located in the stands around the goal area were significantly occluded by the goalkeeper, defender, and goalpost. This level of occlusion has never been seen before in over 9,000 matches that the Hawk-Eye Goal Line Technology system has been in operation.

"The system was tested and proved functional prior to the start of the match in accordance with the IFAB Laws of The Game and confirmed as working by the match officials. The system has remained functional throughout. Hawk-Eye unreservedly apologises to the Premier League, Sheffield United, and everyone affected by this incident."

In 2013, when it was introduced to the Premier League, it was said that Hawk-Eye's high speed cameras had the ability to remove any player's picture obscuring the ball. It is still not understood why it didn't in this match.

After the match, Sheffield United's coach, Chris Wilder said he didn't know if he had to laugh or cry as he was deeply hurt by the decision. It cost them two points.

Sometimes, there are errors with all the technologies around but Goal Line Technology has been a huge success since its inception.

Park Chu Young, Arsenal's Biggest Flop?

 By Matthew

25 December 2020 • 1.08GMT

What if the Lille officials got to the hotel room just before the phone call? Or what if the second part of the medicals weren't needed to finalise the transfer deal? Probably, the nadir of his career wouldn't have started at that time.    

Relegated Monaco had to sell some of their fine players in order to cope with the financial implications the club would face. It turned out to be that Park Chu Young was one of their finest players. Lille were interested in signing him and having agreed a fee of £2.7 million euros with Monaco, they were pretty sure Park was a new player of theirs. Everything went smoothly and Park had completed the first part of his medicals - medicals are a essential part of transfers, if a player fails his medicals, the transfer would breakdown.

He was waiting in his hotel room, Lille officials were on their way, they had a second part of the medicals to finish. Then Park's phone rang while he was waiting, who was on the line? Well, it wasn't his girlfriend wanting to congratulate him on his potential move to Lille, it was Arsene Wenger, yes Wenger, the manager of Arsenal as at that time. Why would Wenger give him a call? He wanted Park to sign for Arsenal. I can imagine Park wondering if he was in a dream or something. He walked out of his hotel room and headed to the Eurostar Terminal. Of course, he was going to the Emirates, London. Lille officials got to his hotel room, but Park was gone. Somehow they tracked him down and found him at the terminal where Park told them he was going to London to sign for Arsenal.

As a 26 year old South Korean, Park had to return to his country for millitary service before the end of 2013 - every able-bodied Korean man must undergo two years in the country's armed services before the age of 28. So Park had to deliver for Arsenal as quickly as he could.

When Park finally arrived at the North London club just before the close of the transfer window in 2011, he was given the legendary No 9 shirt. In a league cup game against Bolton Wanderers, Park scored the winner for Arsenal. But later on, Park would reveal himself as one of Arsenal's biggest ever flops. November 2011, a Champions League match against Marseille was Park's Champions League debut in which he was replaced after 60 minutes due to him being very terrible, his pace was nothing close to a manageable one, it was terribly bad." He did very well last week. Tonight you could see that he lacked the pace of the game a little bit because he has not played enough games" - words of Arsene Wenger on Park after the match. Due to his poor form, he played only six times in the 2011/12 season, one of those were in the Premier League and that single Premier League appearance would go on to be the only English League appearance in his career.

In January 2012, Arsenal re-signed Theirry Henry - a club legend. Phenomenal winger, Robin Van Persie was converted to a striker - Park's original position - and Lukas Podolski was already on his way to Arsenal. Podolski arrived in the summer of that year and the No 9 shirt that Park wore was given to Podolski. Park's new shirt number was 30. With all these, there was no way Park would play since his position was already occupied by better players - based on statistics. What next for Park? He was loaned out to Celta Vigo where he scored four times in 26 outings.

The loan spell at Celta ended and Park was back at Arsenal for the 2013/14 season. October 2013, Arsenal faced Chelsea in the League Cup and of course, Park didn't make the starting XI but luckily he made it to the bench. 81 minutes gone already, Park was subbed on in the game they went on to lose 2-0 and those few minutes he played were the only first team action he was part of for the whole season. His Arsenal career was over and he never played for the Reds again. 

Arsenal released him at the end of the season and he signed up as a free agent for Al-Shabab, a Saudi Arabian club. Presently, he is 35 and plays for FC Seoul in South Korea, his country.

I wonder what part of all these he regrets the most, the part that he signed for Arsenal or the part that he delayed his millitary service for 10 years by obtaining a 10 year Monaco residency visa just to play for a club that he wouldn't make anything out of, well except for the fact that he got richer even though he didn't play, I mean he was on more than £40,000 euros a week. Park's Arsenal career wasn't just a walk in the park afterall.

NOTICE!!!

By Matthew

23 DECEMBER 2020 • 00:17GMT

Hello there, I'm Matthew. Welcome to the Football Correspondent blog. A sports blog dedicated to providing in-depth analysis into European Football.

This blog used to be SM10 Sport, but in order to fully articulate the purpose and contents of the blog and to clearly express the game, Football Correspondent is the new name.

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