MeshSat

Status: pre-release. This is a prototype under active development, not a finished product. It has never been deployed to a real user and has never been used in an actual emergency. See What works, and what does not before you rely on it for anything.

Install

The app comes in two editions. The full app, SMS included, is what the releases here and F-Droid carry. The Google Play edition is the same app without SMS, because Google Play does not allow SMS in an app that is not the phone's SMS app; it is on Google Play and nowhere else. Both are net.meshsat.android, but Play signs its edition with its own key, so a Play install and a GitHub or F-Droid install cannot update each other: to switch, uninstall one and install the other, and provision with the Hub again.

1. Download the APK for your phone from the latest release. There is one per processor: take arm64-v8a unless you know otherwise, since nearly every phone since 2016 is that. armeabi-v7a is for older 32-bit phones, x86 and x86_64 for emulators, and universal works on all of them. A per-processor download is about 47 MB, the universal one about 67 MB. Settings > About phone, or an app like Droid Hardware Info, tells you which one a phone is.
2. Let your browser or file manager install unknown apps. Android asks the first time.
3. Open the APK and tap Install. Play Protect may warn about an unknown developer, because this APK does not come from the Play Store: tap More details, then Install anyway. The APK is signed, and you can check the signature first.
4. Open MeshSat and allow Bluetooth, location, SMS and notifications. Android needs location for Bluetooth scanning.

You need Android 8.0 or later.

Coming from 2.8 or older? Since 2.9.0 the app is net.meshsat.android (it was com.cubeos.meshsat), so Android installs it as a separate app and nothing carries over. Uninstall the old one, install the new one, and provision it with the Hub again by QR code.

Getting started

1. Pair your node. In Setup, open Your MeshSat node, tap Scan for Meshtastic devices, then Connect next to your node and enter its Bluetooth PIN. The scan lists every Meshtastic device in range, so pick the node by its name (a v0 node advertises as MSIR_ plus four hex digits). A plain Meshtastic radio pairs the same way.
2. Satellite. With Use the node's modem on (the default), the app uses the node's RockBLOCK while it is connected. Setup > Satellite shows the modem, with Poll Signal and Check Mailbox, and a Node health card with what the node reports about its own modem: who holds it, its last signal reading, sessions and their results, and the node's own satellite routing. After a restart the app reconnects to the same node and takes the modem back by itself.
3. Hub (optional). Setup > Hub > Scan the Hub's QR code, with the QR code from the Hub. That sets the Hub address, credentials and client certificate.
4. SMS. In Setup > SMS, tap Allow SMS and fill in the Kit phone number.
5. Emergency contacts. In Setup > Safety, add the people an SOS goes to by SMS, then tap Test the alarm to see every route work.
6. Send something. In Messages, tap New message and pick who it is for: a node, everyone on the mesh, a phone number or the satellite. For a satellite message the compose bar shows the bytes and credits before you send. Home shows each way out: a solid line works, a dotted line is not available, and an orange dot is a message on its way.

On first launch a welcome page says what each Android permission is for before Android asks, and Home keeps a Getting started list of these steps until they are done.

Routing rules (Setup > Advanced > Routing rules) decide what is forwarded between links automatically, for example mesh messages out by satellite.

What it does

• Mesh. Meshtastic over Bluetooth LE with the official protobufs: text, positions, telemetry, waypoints, node info, traceroute and more. A reply to a node goes to that node, not to the whole channel. People lists the nodes you hear, with a button to message one or show it on the map, and Mesh topology draws how they are linked from their neighbour info. Region, channels and transmit power are under Setup > Mesh radio settings; the app only sends back values it has read from the radio.
• Satellite. Iridium SBD through the node's RockBLOCK 9603, up to 340 bytes out and 270 bytes in. Messages wait in a queue and are retried until they go out, and a message that arrives during any satellite session is stored straight away. The app opens a satellite session only when there is something to send, when the modem rings, when the gateway holds a message and the modem sees a satellite, or when you tap Check Mailbox. It never checks on a timer and never because it reconnected to the node, because every session costs a credit. If Bluetooth drops in the middle of a session, the node finishes it on its own and the app treats the message as possibly sent and retries it after the modem's 3-minute pause. Passes are predicted on the phone from orbit data that ships with the app and is refreshed when there is internet, and the signal shows as an icon in Android's status bar.
• RockBLOCK 9704 (Iridium IMT), with messages up to 100 KB. A MeshSat node can carry one instead of a 9603. The node says which modem it has, and with Modem on the node on Auto (Setup > Satellite, the default) the app picks the matching driver; 9603 and 9704 override it. A send that sees no satellite within 150 seconds is cancelled in the modem before the app tries again, so the modem never holds a message twice. Through an HC-05/06 Bluetooth serial adapter the code is there, but it has not been tested on hardware.
• SMS through the phone's own SIM, optionally encrypted per conversation with AES-256-GCM. Mesh and SMS messages are compressed with MSVQ-SC by default. It is lossy: what arrives means the same, but may not be word for word what was sent.
• APRS through a KISS TNC over TCP (Direwolf, for example) or directly to APRS-IS, with smart beaconing and acknowledged messages.
• Hub. MQTT with a client certificate. The phone shows up in the Hub's fleet like a field kit, reports health and positions, and takes remote commands: send a message, flush the queue, update config, rotate keys, reboot. When a field kit cannot be reached directly, the app can reach it through a tunnel via the Hub.
• Field kits on your network. Setup > Field kits on your network keeps each kit the phone reaches directly: a name, its address on the LAN (port 6050 unless you say otherwise) and, when the kit has one, its API token. A kit whose operator set a token (MESHSAT_API_TOKEN, or PUT /api/auth/token on the kit) answers a direct request only with Authorization: Bearer <token>; the phone keeps the token in its encrypted preferences, never in a settings export or a log line, and sends it on every direct request to that kit. Check asks the kit for /api/status: a kit that answers 401 gets one line under its card, "This kit asks for its API token: enter it above and check again." Through the Hub's tunnel no token is needed, there the tunnel is the credential.
• Warnings. A MeshSat kit in range puts the public warnings for its area on the mesh (on ALERT_APP and as a text with its relay line). The phone sounds the alarm for each one, vibrates, fills the screen with it while the app is open, and keeps it under Setup > Safety > Warnings until the kit's cancel or a newer warning of the same event; a TEST warning says so and uses the normal notification sound. See docs/WARNINGS.md.
• TAK. What the Hub delivers of your team's TAK picture appears on the map: the phones on your TAK server and your other kits. With Enable TAK on, the phone also sends its own position (once a minute, moving or not), an SOS, a missed check-in and its chat to the Hub as TAK, and the Hub passes them on to your TAK server. The phone needs no TAK server address of its own.
• Reticulum. The phone is a Reticulum transport node and an LXMF endpoint: it exchanges messages with Sideband, CrossTalk, NomadNet and MeshChat over Reticulum, Direct, Opportunistic or Propagated through a propagation node it can also sync from; it finds other Reticulum apps on the same WiFi by itself (AutoInterface) or listens for them on TCP, uses an RNode LoRa radio on USB OTG or Bluetooth, and carries Reticulum over the satellite for an allow-list of addresses, counting the satellite as extra hops so a far client's timeouts cover the round trip. It still relays MeshSat's own traffic between the mesh, both Iridium modems, MQTT and TCP peers.
• Safety. Hold the SOS button on Home for 3 seconds. The SOS goes out on every route the phone has, each one retried until it is sent: by satellite as the Bridge's SOS frame, which the Hub raises as an alarm; as a mesh broadcast, which any MeshSat kit in range relays; by SMS with a map link to each emergency contact; and to the Hub over the internet. It stays on, with a banner on every screen and a line per route saying where it stands, until you cancel it in the app or from the notification. Everyone who got it is then told you are safe. Test the alarm uses the same routes with a text that raises no alarm, and a position report instead of the SOS frame by satellite. A check-in timer sends SOS if the phone sees no activity for too long, and zones, drawn on the map, record when a mesh node enters or leaves an area.
• People you carry. Swap contact cards face to face: one phone shows its card as a QR code under People, the other scans it, and both read the same fingerprint off their screens. The card is signed by the phone that made it, so it cannot be altered on the way, and the fingerprint you read aloud is what says the card is really theirs. A card that arrives as text instead of through the camera is kept, and marked, as imported.
• Records. A message queue with everything waiting, sent or given up, and config export and import in YAML or JSON, in the same format as the Bridge.
• Local API for testing and automation over adb: adb forward tcp:6051 localabstract:meshsat-api, then http://127.0.0.1:6051/api/health. Only adb and the app itself can open it; other apps on the phone are refused.

The map works without internet down to country level, from a world overview built into the app. The gateway runs as a foreground service, so the phone keeps relaying with the screen off; to have it start again after a phone restart, switch on Start after a phone restart in Setup > Advanced > Diagnostics (off by default). Setup > Advanced > Node log shows the node's own log over Bluetooth, the same lines its USB console prints, with pause, clear and share; its switch sets the node's debug log setting, which the node keeps; the node restarts once to apply it. Night mode, the moon on Home, turns the whole app red to keep your night vision.

What works, and what does not

Hardware

Other phones with Android 8.0 or later should work, since the app only uses the standard Bluetooth, SMS and location APIs. If you try one, an issue with the result is welcome.

Build from source

You need JDK 17 and the Android SDK (compile SDK 35).

git clone https://github.com/meshsat/meshsat-android.git
cd meshsat-android
./gradlew assembleFdroidDebug        # app/build/outputs/apk/fdroid/debug/meshsat-android-<version>-universal-<code>.apk
./gradlew testFdroidDebugUnitTest    # JVM unit tests, no device needed

There are two product flavors: fdroid is the full app and the default, play is the Google Play edition without SMS (assemblePlayDebug, bundlePlayRelease). The SMS permissions and receivers live in app/src/fdroid/AndroidManifest.xml, so the Play manifest never mentions them, and SmsCapability gates every SMS code path on BuildConfig.SMS_INCLUDED.

It is Kotlin 2.1 and Jetpack Compose, with Room for storage, ONNX Runtime for the compression model, osmdroid for maps, Eclipse Paho for MQTT, BouncyCastle for Ed25519 and X25519, and NanoHTTPD for the local API. Library versions are in app/build.gradle.kts.

Release signing

Releases are built and signed in CI, with the signing key held in OpenBao, and published on the Releases page. To check an APK before you install it:

apksigner verify --print-certs meshsat-android-2.19.0-arm64-v8a-1172.apk

Every release since 2.8.0 shows:

Signer #1 certificate DN: CN=MeshSat, OU=CubeOS, O=Nuclear Lighters, L=Leiden, ST=South Holland, C=NL
Signer #1 certificate SHA-256 digest: 8ca78b6c33bd9796bb05f40fec2a0ab801e0297e7565960d42f5e6af821c9f66
Signer #1 certificate SHA-1 digest:   9040570a7bf4d33890bf82ad85a7debf24fa57ab

All releases use the same key, so a new version installs over the old one. The one exception is the 2.9.0 rename described under Install. Debug builds are signed with the Android debug key. The Google Play edition is signed by Play with a different key, so it neither updates nor is updated by these releases.

Troubleshooting

The scan does not find my radio. Location must be allowed, Bluetooth must be on, and the radio must not be connected to another phone.

The app stops in the background. Some phone makers kill background services. Set MeshSat's battery use to Unrestricted, and see dontkillmyapp.com for your brand.

The satellite shows 0 bars. That is normal between passes and under a limited view of the sky. The app sends anyway and keeps retrying, so a message can wait a while. Setup > Advanced > Message queue shows what is waiting.

A message shows a clock. It is queued and goes out by itself when it can. A tick means sent, red means it failed.

The map only shows countries. Detailed tiles come from the internet. Offline, the map falls back to the world overview built into the app, which stops at country level.

"App not installed". Usually a signature mismatch with a copy that is already installed, or the old com.cubeos.meshsat app from before 2.9. Uninstall it first.

Related projects

• MeshSat, the Bridge: the same gateway on a Raspberry Pi
• MeshSat node and its firmware, meshsat-firmware
• MeshSat Hub, fleet management
• Documentation and the changelog

Contributing

Issues and pull requests are welcome. Run ./gradlew testDebugUnitTest before you open a pull request, and open an issue first for anything large. Report security problems privately to [email protected] rather than in a public issue; see meshsat.net/security.

License

Copyright 2026 Elli and Kyriakos. GNU General Public License v3.0.

The app is GPLv3 because it includes the Meshtastic protobuf definitions in app/src/main/proto/meshtastic/, which are GPL-3.0. Third-party material and its licences are listed in THIRD_PARTY_NOTICES.md and NOTICE.