Hardware and Networking

Thanks to the substantial prior experience of our project team, developing the hardware and software for You Are Here was not the ground-up endeavor it might have been. Sarah Grant, our project lead, had already developed subnod.es, a self-contained wireless server that runs on a Raspberry Pi and offers basic chat room and digital bulletin board system (BBS) functionality.

While You Are Here built on the subnod.es technology, says Grant, “that project was really only designed to work well in-room.” By design, however, You Are Here was meant to reach into public spaces—in this instance, parks—and therefore required significantly more range.

“We had to make sure that the network range extended beyond just the room,” she says. Though the particular model of Raspberry Pi used to build You Are Here includes a built-in wireless antenna, an external hardware amplifier and antenna were needed to generate a wireless signal strong enough to extend outdoors. Because wireless signals are easily blocked or weakened by physical obstacles, determining how to extend the signal was something of a trial-and-error process.

“There was one antenna that was fifteen decibels that I really wanted, so I just bought it,” says Grant. “When it arrived—it takes up the entire length of my kitchen.” She eventually settled on a nine-decibel antenna that is about a foot long.

A view into the You Are Here hardware unit. The smartphone-looking device toward the left is actually a battery used to power the gray Wi-Fi signal amplifier inside the box just to its right. In the final installed version, we simply plugged in this amplifier. As you can see, all of the components fit easily into an inexpensive black plastic box, in which we easily drilled holes for the antenna and power cords using a standard drill bit.

In our final configuration, the reach of the You Are Here station node is about half a city block in every direction, depending on the nature and number of physical objects surrounding it. “If you’re in a flat, open field, you can get awesome range,” says Grant. “But if you’re in a park where there’s trees or statues or lampposts, all these things block the signal.”

Another goal of You Are Here was to make the physical station small enough to install in a wide range of locations, which placed additional limitations on how powerful the signal could be. At the Tompkins Square Park site, for example, You Are Here had to fit behind the door at the Blind Barber—a well-known barber shop by day and popular watering hole by night. While ensuring that the station’s signal reached as much of the park as possible was a key goal, “There’s also that balance of not showing up to a host with a fifteen-foot antenna,” says Grant. “There are ways to make [the signal] super powerful. But I think the compromise was: we can still cover a good quarter of the park.”