Radon Lets You Share Your Links with Friends using … Ultrasound?

Radon Lets You Share Your Links with Friends using … Ultrasound?

We’re all familiar with the various wireless technologies that are available to us to transmit data between our various devices. Most commonly, we use either WiFi, Bluetooth, or NFC on our smartphones.

In the future, it might be ZigBee or DECT. Whatever technology you use, they each have their benefits. However, one drawback of all of these communication technologies is security. And not because they’re all insecure communication methods — rather, they’re too secure!

shareLet’s say you’re at a gathering with a group of your friends and found an awesome link you want to share. You’re not sharing some super secret banking or investment account detail to your friends, so it’s not like you care about this data being intercepted. In fact, you want everyone around you to receive this link!


How do you do that? Using WiFi would require you to all be connected to the same network. Bluetooth won’t work because you can only pair a few devices at a time. NFC only allows one-to-one communication. In this case, we can use ultrasonic waves to transmit the data we want. A new app called Radon does just that, and it allows you to automatically beam links and text to all nearby Android device that has the app opened up.

How does it work?

The human ear can pick up frequencies in the range of about 20Hz to 20KHz. Any frequencies above or below this range cannot be heard by the vast majority of people (think – dog whistles). Most consumer media devices (ie. our smartphones) are designed to transmit audio in this frequency range. In fact, the maximum output sampling rate of many devices is 44.1kHz, which means the peak frequency can be theoretically as high as half of that or 22.05kHz. In other words, barely outside of our hearing range.


In the real world, many people can’t hear frequencies as high as 20KHz (hence why many children can hear some sounds their parents cannot) and the frequency output of the device’s speaker doesn’t hit the theoretical maximum. But this ends up working out in our favor as we can beam data between 17kHz and 18kHz and most people won’t be able to hear it at all. This is what researchers at Azoft R&D theorized and they developed a mobile application for iOS demonstrating its use.

Although their work didn’t gain much mainstream attention (likely due to the fact that ultrasound isn’t a suitable method of transmitting large amounts of data in a timely manner), it caught the eyes of Google who silently implemented it in their Nearby APIs.

Nearby uses a combination of Bluetooth, Bluetooth Low Energy, Wi-Fi and near-ultrasonic audio to communicate a unique-in-time pairing code between devices. The server facilitates message exchange between devices that detect the same pairing code. When a device detects a pairing code from a nearby device, it sends the pairing code to the Nearby Messages server for validation, and to check whether there are any messages to deliver for the application’s current set of subscriptions.

Sharing using Ultrasound

These APIs were made available to all developers in Google Play Services 7.8, but it doesn’t look like anybody really took advantage of the ability to send near-ultrasonic audio, until now that is.

The moment you open the app, it asks you to enable it to use the Nearby API. Then, it will start scanning for any content being beamed over near-ultrasonic frequencies.

You can quickly send a link or some text by using the share menu and clicking on “Beam with Radon” in order to push the data over. Open up the Radon app on the device(s) that you want to receive the data in, and it will automatically be received and automatically open it up in a browser if it’s a URL. I disabled WiFi, Bluetooth, and NFC on both of my test devices and it shared the URL just fine.

You won’t be able to share images or video files over ultrasound due to the limitations of ultrasound here, but the app will fallback to WiFi or Bluetooth to transmit the data.


Don’t have Radon? No problem! You can share Radon to another device within the app itself. (Go ahead, scan that barcode. I know you want to). No need to mess with pairing anymore, just install the app and you’re good to go.

What do you think of this app? Try it out and let us know how it works for you!

About author

Mishaal Rahman
Mishaal Rahman

I am the former Editor-in-chief of XDA. In addition to breaking news on the Android OS and mobile devices, I used to manage all editorial and reviews content on the Portal.

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