A portable line judge that settles tennis disputes


Gregoire Gentil is a rabid tennis fan but his love of the sport had little to do with his latest invention, which could help reshape the future of amateur tennis.

Gentil, born in Paris and raised on clay, developed a 'Personal Line Call Device,' that fits easier into an equipment bag and can be used on any court.

Gentil attended Stanford during the glory years of men's tennis, culminating with the undefeated 1998 team that featured current Cardinal coach Paul Goldstein and the winningest professional doubles team in Mike Byran and Bob Bryan.

In fact, Gentil has spent the past couple of years visiting the Taube Family Tennis Center nearly every day, using the courts as a personal laboratory. He's even sought out Stanford Director of Tennis Dick Gould (the national Coach of the Year in 1998) for guidance.

"He's been a big help to us," Gentil said from his booth at the Bank of the West Classic at Stanford. "He's been supportive."

During a brief exchange with Gould, he confirmed his support for the product, calling it "outstanding."

"I came to Stanford and I stayed in Silicon Valley," the Palo Alto resident said. "I like to innovate and I'm a tennis player. The technology was there. I just had to put it together."

That's where Tesla entered the picture. It's development of self-driving cars, with software that can recognize the lanes on a road, planted the seed in Gentil's imagination and it grew from there.

Video: a quick demonstration.

"It's the same technology that recognizes the lines on a court," Gentil said. "I started thinking how it could benefit the average tennis player. The technology is already in place and used at tournaments but the cost is prohibitive and its permanently set in place. This you can throw in your bag and carry it around."

The actual gadget has an interesting shape, with the two cameras, one in each 'eye' helping it look a lot like a happy face. It fits in your hand and can be transported in an over-sized tennis ball.

More interesting than making line calls is that it also records where every ball is hitting on the court, which can be downloaded for personal use. It can also play back a replay of the last ball you hit.

Video: Bloomberg report on the device.

"The first thing I wanted to make sure of is that it doesn't cost any more than a tennis racket," Gentil said. "That's about $199. That's what I worked toward."

If it works out for tennis, he'd like to expand it to any sport with a ball, with volleyball coming to mind.

Gentil will be more than happy to demonstrate his device through the closing of the Bank of the West Classic on Sunday. As he puts it, "you can't miss it; it's the only one with red clay."

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