Finally, there’s an enormous showoff factor, both for you and for the manufacturer. How on earth did they fit Wi-Fi circuitry into a regular-size SD card, which could hide behind a postage stamp?
In any case, this week, a new model arrives with an even more amazing trick up its sleeve.
You know how your digital camera gives every photo an invisible time and date stamp? Well, the Eye-Fi Explore ($130) card invisibly stamps every photo with where you took it.
That’s right: photo geotagging has finally come to a camera near you. Noting what photo was taken where used to require either tedious manual data entry or expensive add-on gear. Now it comes cheaply and automatically.
Once on your Mac or PC, each such photo shows the city and state where it was taken. You can also click to view either a street-map view or an aerial photo, clearly showing where you were standing when you pressed the shutter button. At long last, technology has reached a point where we don’t need to write “Eiffel Tower, 1988” on the back of the print as a reminder.
Photo Web sites like Flickr, Picasa and SmugMug can display these maps, too. Certain desktop photo programs, like Photoshop Elements 6, Picasa and (for the Mac) Ovolabs Geophoto.
Now, that’s a pretty interesting trick. But finding out how it’s done is even more interesting.
No, it’s not G.P.S. Even the Eye-Fi people can’t yet shrink a G.P.S. receiver to fit the sliver of an SD card.
Instead, this card incorporates a new technology, a rival to G.P.S., called W.P.S.—Wi-Fi Positioning System. A company called Skyhook came up with it. (Skyhook’s first well-known client was Apple. The original iPhone doesn’t have actual G.P.S., but it does have Skyhook’s “locate me” feature.)
Understanding how Skyhook works requires slogging through some tech talk. But it’s fascinating, and it’s also the key to the Eye-Fi card’s strengths and limitations.
At this moment, more than 70 million Wi-Fi base stations are sitting in homes, offices and shops. Each broadcasts its own name and unique network address (called its MAC address — nothing to do with Mac computers) once a second. Although you’d need to be within 150 feet or so to actually get onto the Internet, according to Skyhook, a laptop can detect this powerful beacon signal from up to 1,500 feet away.
Metropolitan areas today are blanketed by overlapping Wi-Fi signals. At a typical Manhattan intersection, you might be in range of 20 base stations.
Skyhook’s big idea: If you could somehow correlate those beacon signals with their physical locations, you could pinpoint your own location, G.P.S.-style, but without G.P.S..
To that end, 500 full-time Skyhook employees have spent the last five years driving every road, lane and highway in every major American city —and, lately, European and Asian cities. Its equipment measures all those Wi-Fi signals leaking out of homes and stores and offices, and marries that information with the car’s G.P.S. location as it drives.
(Note: At no time does this equipment, or any iPhone or Eye-Fi card, actually connect to these base stations. They’re just reading the one-way beacon signal, which is broadcast even by password-protected base stations.)
So far, Skyhook’s database knows about 50 million hot spots—and the precise longitude and latitude of each.
And that’s it. Now any Wi-Fi gadget equipped with Skyhook’s software, like the iPhone and the new Eye-Fi card, can get a fix on its own position, accurate to around 100 feet.