Wifarer, based in Victoria, B.C., Canada, produces smartphone apps for indoor positioning based on Wi-Fi signals. One of the company’s custom apps guides visitors around the Royal BC Museum (also in Victoria), assisting them in finding their way around and understanding the exhibits.
The Rescue Wand
Firefighters may have to wait a couple of years to get their hands on true indoor location technology. In the meantime, David Cyganski at the Worcester Polytechnic Institute (WPI) has engineered an alternative rescue tool named Mantenna that is much closer to commercialization.
To use it, firefighters would wear radio transmitters that they can activate in a crisis or that will turn on automatically if they stop moving for 30 seconds. The system ensures that transmissions reach rescuers inside or outside a building by using carrier waves between 170 and 200 kilohertz. These very low frequencies penetrate metal and concrete much more easily than do the high-frequency signals that indoor tracking systems use.
While searching for a fallen colleague, rescuers would carry a wandlike, meter-long receiver tipped at each end with a magnetic loop antenna. Up to about 20 meters from the transmitter, the wand falls within its “near field.” The boundaries of a typical building—the strengths of the magnetic fields fall off much more quickly than radio waves at greater distances. in this zone. The wand is allowed to detect the difference in signal amplitude between the two antennas without requiring a preposterously long pole to separate them. Knowing this distance, it can determine when it’s pointing toward the transmitter and calculate roughly how far away it is. It would convey this information to the rescuers with changing tones, flashing lights, and accelerating beeps.
WPI engineers aim to sell a Mantenna transmitter and wand for less than US $1000. They expect to have a prototype within six months.