On your phone? Tap the button above. On a computer? Scan this with your phone:
Short text messages sent as sound — through the phone's speaker and microphone, a cable to a radio, or wirelessly over Bluetooth to a BTech UV-Pro / Vero VR-N76. No Wi-Fi or cellular network needed.
Rattlegram Plus Plus is an independent fork of Rattlegram Plus by BI3BJU, which itself builds on Rattlegram by aicodix. It installs alongside Rattlegram Plus (it has its own app ID) and uses the same over-the-air format, so messages, pings and encrypted messages (with the same password) should work between the two apps.
| Encrypted message | Encrypted picture | Wipe All Data | Danger Zone |
|---|---|---|---|
 |
 |
 |
 |
- 🕵️ Hide your call sign (new in 1.2) — Danger Zone → Password → "Hide my call sign in encrypted messages". Encrypted messages, locations, pictures and acknowledgments then go out as ANONYMOUS; your call sign travels inside the encryption, so only stations with the password (and 1.2 or newer) see who sent them. Off by default; a "🔒 Call sign hidden" note shows under the Encrypt box while it applies. Amateur bands require station identification, so use it only where that is legal.
- 🧨 Wipe All Data (new in 1.2) — the red button in the top bar erases everything the app has stored (messages, pictures, locations, password, call sign, contacts, settings) after one confirmation, removes the app from Recent apps and closes it.
- 🔒 App lock (new in 1.2) — Danger Zone → Lock App on Open. When the app is opened fresh it stays covered until you confirm with the phone's fingerprint, face or screen PIN; screenshots and the Recent apps preview are blocked while it is on. Needs a screen lock on the phone; off by default.
- 🔓 Unlock later (new in 1.2) — encrypted messages that arrived before you had the right password are decrypted as soon as you enter it, including hidden call signs and locked pictures.
- 🔁 Safer resend (new in 1.2) — long-pressing a message now asks before sending it again, encrypted when a password is set, and warns when it can only go out unencrypted.
- 🖼️ Pictures (new in 1.1) — Compose → Picture: take a photo or pick one, choose Small/Medium/Large, optionally Robust and Encrypt. It goes out as a series of ordinary Rattlegram messages with spare parts, so a few lost parts are rebuilt automatically. Photo metadata (GPS location, time, camera) is removed; only the pixels are sent.
- ✅ Acknowledgments (new in 1.1) — Menu → Acknowledgments: Off, Messages addressed to me (
@CALL ...), or All messages. The sender's message gets "✓ Acknowledged by …". Your radio transmits the short ACK on its own, so it is off by default. - 🔐 Remember password (new in 1.1) — optional; stored encrypted with a key that never leaves the phone and excluded from backups.
- 📍 Encrypted location sharing (new in 1.1) — the Encrypt box now works for locations too; the map pin is labelled with the sender's call sign.
- 📻 Bluetooth radio audio — Menu → Bluetooth Radio connects to a paired BTech UV-Pro (and, by the same protocol, Vero VR-N76). Receive and transmit go over Bluetooth; the radio keys while it receives audio and is always unkeyed afterwards. No cable or DigiRig.
- 🔇 Automatic radio speaker mute — while connected, the radio's speaker is muted and its volume restored on disconnect (also after an unexpected drop).
- 🪖 SALUTE report — a form for Size, Activity, Location, Unit, Time, Equipment. Location from GPS as Lat/Long, Maidenhead or MGRS (or typed); time in UTC or local; a live byte counter so the report fits, including in encrypted messages.
- 🔑 Password by QR code — show the encryption password as a QR code, scan it on the other phone, or paste it. No more typing 64 random characters.
- ☑️ Encrypt checkbox remembers its last setting.
- 🗑️ Delete Messages on Close (optional, Danger Zone).
- 🧩 Fixed overlapping buttons in the password dialog.
- 📡 Audio-based messaging (audible or ultrasonic)
- 🔐 Optional end-to-end encryption (AES-256-GCM, password based)
- 📍 Location sharing, opened in any map app
- 🔁 Repeater (relay) mode, 🕊️ loop beacon, 📶 spectrum analyzer
- 👤 Contacts, 🌙 night mode, persistent message history
- 🎚️ Sample rate, channel, audio source, carrier frequency and leading-noise settings
- Download the latest APK: RattlegramPlusPlus.apk (always the newest version; older ones are on the Releases page).
- Allow your browser or file manager to install unknown apps when Android asks.
- Install and open it, then allow the microphone (needed to receive) and, if you want GPS features, location.
Requires Android 7.0 or newer.
The early
v0.1-testbuild used Rattlegram Plus's app ID. If you installed it, uninstall it before installing Plus Plus.
- Pair the radio once: put the UV-Pro in pairing mode (its light flashes red and green — see the radio's manual), then pair it in Android's Bluetooth settings. It shows up as
UV-PRO. (Menu → Bluetooth Radio → Connect / Disconnect → Pair new radio walks through this.) - Close other apps that use the radio, such as HTCommander — the radio allows one connection at a time.
- Menu → Bluetooth Radio → Connect / Disconnect, pick the radio, tap Connect. The status shows Listening via UV-PRO.
- Send and receive as usual. While connected the microphone is off and the audio rate/channel settings are locked.
Tested with a UV-Pro (firmware 0.9.3) and Samsung Galaxy A15 phones. The Vero VR-N76 uses the same protocol but has not been tested yet — reports welcome.
Compose → Picture, then take a photo or choose one. The preview shows the size, the number of parts (plus spare parts) and about how long it will take. Tips:
- Small is usually enough; a detailed photo is around 2–5 KB and takes 1–3 minutes.
- Tick Robust on weak links. It is slower but needs a few dB less signal.
- The receiver needs Rattlegram Plus Plus 1.1 or newer; other Rattlegram apps show the parts as text.
- If parts are lost beyond the spares, the receiving bubble says how many are still needed; the sender can tap the picture and choose Send again.
Danger Zone → Password: Generate Random Password, then Show QR on one phone and Scan QR (or Paste) on the other, and tap Okay on both. Anyone who sees the QR code can read your encrypted messages, so only show it to people you trust. The password is only kept between launches if you tick Remember password on this phone.
git clone https://github.com/doodlecomms/Rattlegram_Plus-Plus.git
cd Rattlegram_Plus-Plus
./gradlew assembleDebugOpen it in Android Studio, or build from the command line as above (needs the Android SDK and NDK 28.2).
Release builds are signed with the key described in a keystore.properties file in the project root (it is git-ignored and never committed):
storeFile=/path/to/your-release-key.jks
storePassword=...
keyAlias=...
keyPassword=...Without that file, ./gradlew assembleRelease falls back to the debug key.
| Permission | Why |
|---|---|
| Microphone | Receive messages through the microphone |
| Location | GPS for location messages and SALUTE reports |
| Bluetooth (nearby devices) | Connect to a BTech UV-Pro / Vero VR-N76 |
| Camera | Scan a password QR code (asked only when you tap Scan QR) |
| Internet | Map display for received locations |
- Rattlegram — Copyright 2022 aicodix GmbH, BSD Zero Clause License. Modem, polar codes and DSP: aicodix/modem, aicodix/code, aicodix/dsp.
- Rattlegram Plus — BI3BJU: encryption, location sharing, contacts, beacon, Material UI.
- Rattlegram Plus Plus — doodlecomms: the additions listed above.
- Bluetooth protocol details from HTCommander by Ylian Saint-Hilaire (Apache-2.0). The code here is an independent implementation.
- Third-party libraries and their licenses: see THIRD_PARTY_NOTICES.md.
This project is released under the BSD Zero Clause License, see LICENSE.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE. Transmit only on frequencies and with content you are licensed for. Many amateur radio rules do not allow encrypted messages — check your local regulations.