Electronic line judge, an electronic system used in tennis to automatically detect where a ball has landed on the court

An electronic line judge is a device used in tennis to automatically detect where a ball has landed on the court. Attempts to revolutionize tennis officiating and the judging of calls in the sport began in the early 1970s and has resulted in the design, development and prototyping of several computerized, electronic line-judge devices.

The Electroline; the first computerized, electronic line judge device, introduced in 1974. An elec­tronic line judge is a de­vice used in ten­nis to au­to­mat­i­cally de­tect where a ball has landed on the court.