GoTenna creates a cell network out of thin air anywhere on Earth

The Brooklyn-based startup is offering a solution for off-the-grid travelers who need low-cost connectivity for their smartphone -- and it doesn't rely on satellites.

Nick Statt Former Staff Reporter / News
Nick Statt was a staff reporter for CNET News covering Microsoft, gaming, and technology you sometimes wear. He previously wrote for ReadWrite, was a news associate at the social-news app Flipboard, and his work has appeared in Popular Science and Newsweek. When not complaining about Bay Area bagel quality, he can be found spending a questionable amount of time contemplating his relationship with video games.
Nick Statt
5 min read

GoTenna is a pocket-size communication tool that lets smartphones talk to one another without cell service. GoTenna

Our modern, wired society often romanticizes going off the grid. Pack-toting hikers bravely venture into areas without electricity or -- gasp! -- cell service, unfortunately inhibiting the posting of that picture-perfect Instagram shot.

While few discount the benefits of unplugging now and again, it's not necessarily safe to trek miles into the wilderness without a backup plan -- or for that matter to live even in urban areas potentially crippled by a natural disaster. That's why people often shell out anywhere from $500 to $1,500 for a trusty Globalstar or Iridium satellite phone.

GoTenna, a Brooklyn-based hardware startup, has a modified, smartphone app-based approach to staying in touch at a lower cost when cell service is shaky, no satellite connection required. The device, a thin 2-ounce wand that can be strapped to a backpack or belt loop, connects to a smartphone app via Bluetooth low energy (LE). Slide out the antenna and power on the device and you'll then be able to send messages and GPS coordinates from your smartphone to others connected to a GoTenna. The company offers downloadable, high-resolution offline maps for referencing transmitted location data.

GoTenna doesn't give your smartphone LTE-style data, so no Twitter scrolling or Facebook browsing. What it does is create a low-frequency radio wave network for its iOS and Android app that can last around 1 mile in skyscraper-filled urban areas, but up to 9 miles in most outdoor situations like hiking and camping. If you're climbing or, say, out skiing, it shoots from 9 miles to as high as 50 miles once you start ascending to higher elevations.

GoTenna is 5.8 inches in length and weighs 2 ounces. When the antenna is extended, which is required for use, the length extends by 2.2 inches. GoTenna

"That's just the science of radio waves. We are operating at the limits of physics," said GoTenna co-founder and CEO Daniela Perdomo. "If the Earth was curved a different way, you could get more miles than that."

The idea is to allow text messaging both between fellow off-the-gird participants and someone located within the net of reliable cell service in the case of an emergency. There's also a function, called Shout, that lets you transmit information to any GoTenna devices in range. Messages are end-to-end encrypted and not stored anywhere. They also can be set to self-destruct once the recipient reads it.

"You get delivery confirmation," Perdomo said. "Unlike walkie-talkies where you send something out into the void, there's no guess work here." Bridging the gap between WhatsApp and a satellite phone is the point.

"The experience of using this should be the same as a messaging app on your smartphone," she said, though it comes with a bit more juice. A GoTenna can last up to a year and a half on a single charge if it remains off, and its lithium-ion battery will last for 72 hours of occasional use, Perdomo said.

GoTenna is taking preorders starting Thursday. For $149, you get a pair of devices. Following the first batch of sales up to $50,000, GoTenna plans to raise the price to $299 per pair.

Bootstrapped in Brooklyn

Not often does a hardware startup go from product inception to full-blown company without a major financial backer. Yet GoTenna managed to hatch out of Brooklyn's NYC Resistor hacker space -- where 3D printer company MakerBot got its start -- without the footing provided by a venture capitalist. Prior to a much-needed funding round late last year, led by firms Andreessen Horowitz and Bloomberg Beta, GoTenna was completely self-funded for much of its first year.

The brainchild of Perdomo, a former journalist and startup product manager, and her brother and now-CTO, Jorge Perdomo, the company was born from the connectivity nightmare following 2012's Hurricane Sandy. In the aftermath of the storm that devastated the tri-state area that fall, many residents were facing downed cell towers that left them out of contact with friends and family.

That's precisely why GoTenna isn't aimed solely at off-the-grid trips like hiking and camping. Its other use cases are traveling abroad without a dedicated SIM card, attending large-scale events like concerts and sports matches, and during natural disasters that leave cell service crippled and unreliable.

GoTenna's iOS and Android app can sync with your phone's contact list -- or rely on an anonymous ID -- to send messages and location data. goTenna

Now that it's on sound financial ground, the team of six -- four additional engineers alongside the Perdomo siblings -- are using a presale campaign to gauge demand for their first batch of GoTennas. The road here, however, was complicated and not without failure.

"Our first device worked on the 900 Mhz band and was huge and worked over the audio jack," Daniela Perdomo explained. GoTenna was originally conceived as a kind of phone case that would forgo the need for a wireless accessory. However, that frequency -- allocated for amateur (also known as ham) radio and some walkie-talkie equipment -- wasn't reliable enough. It cost the company more than just a few product design iterations to maneuver to something wireless.

"We are now at a device that is Bluetooth LE-enabled that works on the 151-154 MHz range," Perdomo said. "The propagation characteristics of these waves are so fantastic. They like to turn corners, go over mountains, they interact with matter well."

Even more challenging than designing a slide-able, tiny antenna, and ensuring that the device's own circuitry wouldn't interfere with its capabilities, was creating their communication network. It needed to be one that could operate without talking to a server and wouldn't choke on itself as it expanded.

"Some of the more interesting and novel stuff we're doing is on the network layer," Perdomo said. "The No. 1 thing is how do we make this work without any central server -- every one single person being their own autonomous node."

Then there's the matter of increasing the distance and number of devices while avoiding interference, often a problem with mesh networking apps that attempt to create Bluetooth webs using the limited native antenna inside a smartphone. "Even if there's a million people hitting send in the same area of influence at the same second, how do they not all step over each other?" Perdomo said.

The team decided that asynchronous bursts of text, instead of real-time voice, was the way to go and relied on rigorous testing to ensure it could be sustained at scale. "People have been using radio frequency technology for a century. That's easy to model out," Perdomo explained. Still, the company has put hundreds of devices within range of each other. And on the virtual side, many more.

"We've been running simulations with not hundreds, but thousands and thousands of people," she added. "We learned a lot. It's hard to work with these invisible things and getting to be really power-efficient and transmitting at the range you want, and getting to the right people."

Boiled down singularly, the scrappy team that backed their hardware startup with their own money thousands of miles from the heart of Silicon Valley learned the oft-quoted tech lesson: Hardware is hard.

"Radio frequency engineering is really hard. It's truly a black art," Perdomo said. If all goes according to plan, GoTenna's black art will be what powers a seamless experience that, like most modern technology, we often use as if it really were magic.