Radio waves

How to explore the hidden world of radio waves all around you

One day this fall, in an old factory in Brooklyn’s Bushwick neighborhood, a row of ’90s pagers chirped and buzzed. Next to their dimly lit screens was a receipt printer – like the one you might find in a cash register – spitting out long spools of paper. As my eyes scanned the prints, I couldn’t believe what I was seeing: they were pager messages from dozens of doctors and hospital workers, filled with very personal patient information.

The Holypager Art Project. Image: Brannon Dorsey

The installation this year Radical networks conference was part of a work called holypager by Brannon Dorsey who used a programmable radio to listen to traffic for pager messages. While you might think this would require the skills and resources of a spy agency, it’s actually quite simple for even the most modest tech savvy.

When pagers became popular in the 1990s, very few people understood how they worked and the technology they depended on was extremely expensive. The designers of the pager network therefore got away with sending each message unencrypted, relying on the pagers themselves to display only the messages addressed to them. Today, however, following readily available instructions and using a cheap USB radio, almost anyone can build a pager that receives all messages broadcast in their area, not just those addressed to them.

Dorsey’s project is part of a larger movement in which artists and journalists are using new radio technologies to explore the politics and implications of the design and use of hidden infrastructure.

While the radio may seem like an outdated technology, it’s actually an ubiquitous part of modern life. Radio signals from Wi-Fi routers, GPS satellites, Roku remotes, wireless water meters, Bluetooth keyboards, weather stations and even echoes of the big bang all saturate the air around us.

Until recently, it was relatively difficult to explore this vast and unseen world. AM/FM radios have been cheap and readily available since the popularization of the transistor in the 1960s, but devices that let you tune off frequencies like the 88MHz-108MHz band of FM radio were hard to come by and usually cost thousands of dollars. dollars.

Everything changed in the early 2010s. A group of pirates discovered than the chips that powered many cheap USB digital TV tuners could be reused to tune an incredibly wide frequency range, from 24 MHz to over 1000 MHz. Today, these Software Defined Radios (SDRs) can be picked up for about $20 on Amazon and are supported by a active open source community.

The opportunities this new technology has provided for investigative journalists and socially engaged engineers have proven vast. For example, Buzzfeed News published a major story in August that revealed the extent to which law enforcement is using Stingrays (devices that pretend to be cellphone towers and are used to surreptitiously track people) by analyzing data from radio signals that planes use to report their location.

Artist Surya Mattu has also used Software Defined Radios in a recent work shown at the Whitney Museum of American Art in New York which revealed the names of all the Wi-Fi networks our phones connected to. While the engineers who designed Wi-Fi thought it would be useful for our phones to try to automatically connect to a network, they unwittingly built a system that leaked intimate information about us into the air, like the name of a hotel visited on a recent trip or the network at an ex’s apartment.

Agree in oneself

It has never been easier for anyone to explore the radio spectrum. All you need to get started is $20 software defined radio— essentially a USB stick with an antenna that allows your computer to tune into the radio waves around it.

Once you have a physical radio, you will need to use different software to make sense of the signals you are picking up. Audio transmissions are the easiest to use.

Image: Screenshot/Marc DaCosta

GQRX is a popular open source radio receiver that works on Mac, Windows and Linux. Open it up and type in 91.1 MHz and, if you’re in the New York area, you’ll be treated to eclectic tunes from the alternative radio station. WFMU. However, if you type in 476.68750 MHz, you can listen to radio traffic from the NYPD 94th Precinct, which serves the Williamsburg and Greenpoint neighborhoods of Brooklyn.

Knowing which radio frequency to tune into can be as difficult as knowing which URL to type into your browser, but there are plenty of resources that can help.

Communities of police scanner enthusiasts have published frequency lists you can go online for years, but the real goldmine of information (at least in the US) is maintained by the Federal Communications Commission (FCC).

While today the FCC is best known for dismantling net neutralityit was originally created to regulate radio transmitters partially in response to the sinking of the Titanic in 1912. The ship’s distress calls had been drowned out by interference ashore, contributing to its demise.

This broad mandate gives the FCC some control over everything from microwave ovens to satellite uplink transmitters. A benefit of this regulation for amateurs is that anyone wishing to use a radio that transmits above a certain signal strength must obtain a license, and all such licenses are public data.

This image shows how all pieces of the radio spectrum are allocated by the FCC. Image: US Department of Commerce

Different portions of the radio spectrum are reserved for different uses such as FM radio, aeronautical navigation, and satellite transmissions, among others. Image: US Department of Commerce/annotations added by author

The FCCs License View Database is a great resource for finding out who is likely using radio waves in your area. Taxi dispatchers, UPS sorting facilities, McDonald’s drive-thrus, maintenance radios in office buildings, even wireless microphones like the one that Donald Trump sadly forgot was on— are all reflected in the FCC data.

Enigma Public provides a more user-friendly experience for finding FCC licenses. Image: Screenshot/Riddle

The FCC website will allow you start research through licenses, but the interface is limited. Public Enigma—a public data search and discovery platform I helped launch—also archived the FCC data and enables a more feature-rich and user-friendly experience. For the more daring, you can download the entire database of almost 20 million licenses to work directly (if you have database experience I also made a library which facilitates geographical research).

Dig into data

Beyond simply listening to voice conversations, there is also a lot of interpretable data circulating on the airwaves. A strong open source community has created specific software that allows you to transform signals broadcast on particular frequencies into readable data.

Here is a selection of the types of things you can do:

When I was a child, I remember being totally amazed when I learned that the visible light we can see is the same thing – the same electromagnetic radiation – as radio waves or X-rays which we cannot no see. What kind of eyes would it take to see that other stuff, I wondered.

Last year, China completed construction of the the largest radio telescope on the planet, making it the world leader in the search for extraterrestrials. As the Earth spins through space, the telescope’s antenna is pointed into the depths of the universe, hoping to hear a bit of conversation from a distant world. While a radio plugged into the side of a laptop might have a more limited range, it promises to open up new realities to explore.