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Navigating the Notion of Pedestrian Dead Reckoning

Dead reckoning. Unless you’re a pilot, you probably haven’t heard the term in a while. Refresher: It’s a navigational term, used to deduce (the “ded” of “dead reckoning”) where you are and where you’re going, using the last known information about your location.

Charles Lindbergh deadreckoned his way over the Atlantic to Paris in 1927 using its basic formula — distance equals speed multiplied by time.

Now, dead reckoning gains a new and kind of odd prefix: pedestrian dead reckoning. It’s a way of using WiFi and the sensor-enabled stuff in our gadgets to find other stuff indoors — like how your Garmin used to navigate you to physical addresses, outdoors (before your phone’s map app did).

In short, pedestrian dead reckoning — abbreviated “PDR” — is a little bit GPS (global positioning system), a little bit WiFi, a little bit accelerometer and a little bit magnetometer.

Refresher: GPS works over satellite, with predictable results once you drive into the parking garage. WiFi is WiFi. Accelerometers measure, well, acceleration. They’re what’s inside your FitBit, Fuelband, or other digital pedometer. Magnetometers power your phone’s compass app.

Put it all together, with an app on top, and suddenly Costco could offer a “mobile butler” that senses when you’ve entered the store, and when you’ve stayed still for a time. It could ask: Can I help you find something? Paper towels? Follow me — I’ll show you the way. Then your sensor-equipped gadget (meaning your phone) and app does just that.

That’s but one example in what has to be dozens of use cases that blend WiFi, pedometer and compass. Pedestrian Dead Reckoning: It’s coming, and it’ll either save us time, or drive us nuts. Maybe both!

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