Throughout the past decade we have seen the gradual - but fast - integration of more technologically advanced systems into sports. Some have been used in tennis as early as 2009 and some are more recent additions as in the last half-decade. These include the likes of GLT, EPTS and the infamous VAR.
 
VAR (video assistant referee), simply, uses cameras to monitor stadium games to aid the referee in decision making. Camera images are watched by a team of VAR officials who, as necessary, communicate via radio with the on-pitch officials. The need for/use of VAR is indicated by the notorious outline of a TV made by the referee (something Anthony Taylor should do much more often). Before the advent of VAR, there were only about 2 cameras in a stadium, managed by a team of 8. But now, with modern-day broadcasting and VAR, there can be more than 30 cameras in a stadium managed by over 100 people. Some cameras operate at incredibly high speeds such as 50 fps.
 
VAR is the most infamous form of "modern technology" in football but another you may see occasionally and which has decided many crucial events is Goal Line Technology (GLT). GLT is used to discern whether or not the ball has actually fully crossed the goal line. Two types of technologies can be used for this. Camera-based GLT or magnetic-based GLT. Camera-based technologies use cameras to discern whether or not the ball has crossed the line. It is the same technology that has been used in cricket and tennis for well over a decade now, such as Hawk-Eye.
 
FIFA currently uses the GoalControl-4D system for the World Cups. There are 14 high-speed cameras around a pitch; seven cameras focused on each goal to catch the ball's position. A computer software analyses the footage to get the ball’s position as x, y and z coordinates. It also includes its speed, meaning the measurement is four dimensions. If the ball fully crosses the goal line, the computer automatically sends a signal to the referee’s watch in less than one second.
 
The computer uses a triangulation method to calculate the ball’s precise position. Triangulation is a method of calculating the position of an object by measuring the lengths and angles of several connected triangles. This entails measuring the length of one side of each triangle and then deducing its other angles and lengths accordingly. The system software then creates a 3D image of the ball relative to the goal line by calculating the ball’s location in each frame by identifying the pixels that correspond to the ball. Camera technology via triangulation produces mostly reliable results even when players’ bodies are obstructing the views of some cameras. Because 3 cameras are present, if the view of one is blocked, the other two can take over quite simply – if needed.
 
The magnetic-based technology for GLT is radio-based systems that use a magnetic field to detect when a goal can be awarded. At the point when the ball crosses the goal line, the magnetic field is disturbed. A signal is generated and transmitted to the system computer, which, in turn, transmits a signal to the referee's watch enabling the 'goal' to subsequently be allowed or disallowed. The whole process all takes place in less than one second. The magnetic field is created either by underground cables and devices installed in the goal frame or with antennae. The balls used with this system contain electronic circuits. Notably, this does not impact the functioning of the ball and is rather seamless. The signals generated are also encrypted to prevent unauthorised access or tampering of information. 
 
Finally, possibly the biggest change to football over the past decade with the help of computers and technology is the amount of player information obtained. Nowadays, in modern sport, whenever a player does anything, it is recorded. From something as simple as a pass to something as complicated as the xA statistic (expected assists). This is now occurring to the extent in most sports that there are hundreds of websites with comprehensive data about what every player and athlete has done, including all of their statistics. One way in which this is achieved is through EPTS.
 
Electronic Performance and Tracking Systems (EPTS), which include camera-based and wearable technologies, are mainly used to track player and ball positions but can also be used with microelectronic devices and heart-rate monitors, as well as other devices to measure data such as heart-rate, distance travelled, passing, pressing, and top speed. It can also track how great the impact of a tackle is. Each team has three EPTS devices; one for an analyst in the stands, another for an analyst on the bench, and a third for the medical team. Optical tracking cameras are used to monitor the players and the ball and to then provide feedback. It works with camera-based systems and wearable technology. 
 
There are three forms of physical tracking devices available currently: optical-based camera systems (OBTS), local positioning systems (LPS), and global positioning systems (GPS)/global navigation satellite systems (GNSS). OBTS simply involves cameras around the pitch to track the players. They use tracking algorithms to ensure they identify players and the ball correctly. It uses a similar but more efficient version of the technology which identifies specific faces in pictures on phones. They are also the most used form of EPTS and were introduced far earlier because they don’t require the players themselves to wear any tracking devices. Since it is able to provide constant data, it is favoured among coaches with a high (desired) degree of precision. There are some downsides though.
 
Most significantly, a good OBTS takes a significant investment to set up with a number of cameras required, and then analysts to sort through and correct data. LPS works in a similar way to OBTS but with one pivotal difference. Instead of tracking the players optically, they track LPS transmitters that players wear which emit high-frequency signals. This means that while the setup is very similar to an OBTS because the pitch is surrounded with sensors (instead of cameras this time), the data can automatically be used without the need for editing as it is impossible to ‘lose’ a player. This enables the data an LPS gathers to be used instantly and provide in-game analysis, which naturally gives it a huge advantage, especially for coaches looking to make rapid decisions. This system is also the most precise tracking system available, being accurate to just 50mm of where each player is. The transmitters players wear on their backs have shown to be barely noticeable by players and fans alike on the field, and LPS have become widely adopted by almost all top-tier teams.
 
Finally, GPS are significantly different to the previous systems as instead of the data being gathered by pitch side cameras or sensors, players wear GPS units that send information all the way up to satellites in low orbit above us, which then record this data and allow the user back down by the pitch to access it. The upsides of this system are obvious: you no longer need lengthy and expensive setups by the pitch, or even a technical operator to work them. All players need to do is put on their GPS unit. However, because the data is being transmitted to space, it is not as good for precise details such as the exact position of your striker relative to the offside line, for example. The GPS devices are also a lot more cumbersome than LPS as they need to provide a far more powerful signal. They are used by lower league teams.
 
But even after all this investment into technology in modern sport, there are still numerous inaccuracies: multiple investigations and studies have revealed that officials analysing VAR tend to be off by about 132 milliseconds. While that may seem to be only a minute discrepancy, in the fast paced game of football, it can (and has) resulted in erroneous calls by VAR, cancelling legitimate goals or failing to call a genuinely offside play. Though, as time progresses, it is already clear that modern computing will play an increasingly major role in the years to come. Not only so in refereeing, but in coaching and developing the next generation of athletes worldwide.