Developed by the team at aicodix GmbH, Rattlegram brings together advanced digital signal processing and clever open-source software to let your phone do something truly unique: send and receive messages through sound, much like how old-school modems used to—but way more modern and mobile-friendly.

What Is Rattlegram?

Rattlegram is an innovative app that turns your smartphone into a two-way audio communicator for text. It uses a method called COFDMTV (Coded Orthogonal Frequency Division Multiplexing with Time Variation) to encode text into sound. Your phone’s microphone and speaker become the only tools needed to “hear” or “speak” messages.

You can try it out yourself on both iOS and Android:

• Download for iOS
• Download for Android

And if you’re curious about how it works in action, check out the short demo and community videos here:

How Does It Work?

Rattlegram relies on several open-source projects developed by aicodix:

• OFDM Modem
  Core engine for encoding and decoding messages:
  github.com/aicodix/modem
• Polar List Decoder
  Used for reliable error correction:
  github.com/aicodix/code
• DSP Library
  Handles the nitty-gritty of digital signal processing:
  github.com/aicodix/dsp

All of these are released under the extremely permissive BSD Zero Clause License, meaning the code is not only free to use—it’s free to build upon with zero restrictions.

Respecting Your Privacy

Because Rattlegram listens for sound-based messages, it does require access to your phone’s microphone. But here’s the good news: your privacy is fully respected.

• The app does not record or store any audio.
• It uses a temporary buffer in memory just long enough to decode the signal.
• Only the final decoded text message is saved to your device’s storage.

You’re in full control, and everything happens transparently and securely on your device.

Why Try Rattlegram?

Whether you’re a tech hobbyist, amateur radio enthusiast, or just curious about sound-based communication, Rattlegram is worth exploring. It’s open, experimental, and surprisingly fun. You can even use it offline—in a noisy room, at a hackathon, or to communicate without the internet.

So go ahead—send your first message over sound and experience digital communication in an entirely new way.

Visit aicodix.com for more information or to dive deeper into the technology behind Rattlegram.

Let your messages rattle through the air—with Rattlegram.

The post Rattlegram – The Sound of Digital Messaging appeared on Hamradio.my - Amateur Radio, Tech Insights and Product Reviews by 9M2PJU.