Image recognition – defense against a Lampard replay?

Anyone for GPS?

It would seem that if you can track an iPhone or a stolen laptop using GPS or post your exact whereabouts in a massive city like New York on your phone using Glympse, you could track the position of a ball and 22 players in the relatively small area of a football pitch. Load them up with GPS tracking, and you're off.

Unfortunately, while GPS services can give your general position in a Times Square, they aren't accurate enough for the beautiful game.

GPS needs a line-of-sight to the satellite overhead. Otherwise, you get inaccurate and delayed results as the signal is obscured by buildings or gets bounced around. GPS is accurate to within 50 to 100 feet.

Ted Morgan, chief executive of location-based service provider Skyhook, which powers the iPhone and devices from Dell, Samsung and Motorola, said football would be the worst of all scenarios for GPS. The desert just outside Baghdad is ideal because the lack of structures – and people.

"Human beings are the worst thing to have around because they are full of water - they make the signal bounce like crazy and you have stadium full of metal that acts like a satellite dish. Open fields are awesome," Morgan said.

GPS can be boosted using a couple of techniques. You can triangulate a device's location using information from nearby cell-phone towers – called Assisted GPS. Also, you can use Wi-Fi with a device measuring the strength of signal from Wi-Fi transmitters and triangulating based on the identity of the Wi-Fi transmitter that the receiver has passed near. Skyhook takes advantage of Wi-Fi, GPS satellites, and cell towers plus its own positioning algorithms – and still it's looking at between 30 and 60 feet.

Geoff Glave, product manager with Absolute Software that tracks stolen PCs using GPS and Wi-Fi, puts Wi-Fi's accuracy at between 100 and 200 feet. "If you are holding a device and move 14 inches you are not going to see it - not until you walk a couple of feet will you see a change," Glave said.

Wi-Fi has an added complication. For more accuracy you must map the venue to try and pinpoint an object – a timely and potentially costly exercise that can militate against its use. But again, you're talking about a range of nine to sixteen feet in accuracy, says Skyhook's CEO.

RFID tags could be another potential answer. However, tags are only registered when they are near sensors, so you'd need to cover the ball and players with tags and the pitch with sensors.

Morgan is horribly realistic about the chances for GPS for the foreseeable future. Researchers are chipping down the yards, but the sweet spot for geo-location remains consumer devices where you only need an approximate location – such as the position of a hotel or a restaurant on a street.

"I think technology is overkill. They should try the tennis stuff - that works pretty well," Morgan said of football. He didn't name it, but the chief of a GPS and WiFi positioning company relied upon by millions of iPhone and Android users to plot their positions was talking about Hawk-Eye. ®