Meshtastic USA: settings, FCC rules and getting on air

US settings at a glance

With slot 0 (the default), the node picks its frequency from the channel name, so everyone on the default LongFast channel lands on 906.875 MHz. Your region, preset and channel must match the people you want to reach, so check with your local mesh.

What the FCC rules mean

Meshtastic in the US runs unlicensed under FCC Part 15. The band allows up to 1 W, but only for certain kinds of signal, and LongFast isn't one of them.

That's why Meshtastic 2.8, in alpha since September 2026, makes Long Turbo the default when you first set the region to US on the node's own screen: in the developers' words, it uses 500 kHz, "so a new US node starts on a preset that meets the requirement". Upgrading doesn't change the preset you already use, and setting the region from an app or the command line may leave a node on LongFast, depending on the app. Long Turbo and LongFast can't hear each other: Long Turbo's default channel is on 908.750 MHz, LongFast's on 906.875 MHz, so a new node on Long Turbo won't hear a LongFast mesh. Whether a 500 kHz LoRa signal measures 500 kHz at the 6 dB points depends on the radio, so the device's FCC grant is still what decides what's legal. Ask the maker what its grant covers for the mode, antenna and power you plan to use.

Part 15 devices mustn't cause harmful interference and have to accept any they receive (§15.5). There's no duty cycle rule for these modes, but everyone shares the channel, so keep position and telemetry intervals sensible.

Which preset?

All the nodes you want to reach must use the same preset. Each preset's default channel lands on its own frequency, so a mesh on MediumFast won't hear one on LongFast.

Link budgets are Meshtastic's figures at 22 dBm with a 0 dBi antenna. Firmware 2.8, still in alpha, adds more presets, including Medium Turbo and the very narrow Tiny Fast and Tiny Slow. The developers recommend busy meshes, with more than about 60 nodes in range of each other, move off LongFast. The San Francisco Bay Area mesh, for example, moved to MediumSlow.

Licensed amateurs

902 to 928 MHz is also the 33 cm amateur band, where Part 97 allows more power than Part 15. But Part 97 bans messages encoded to hide their meaning (§97.113), so licensed mode turns encryption off and sends your callsign. Licensed nodes can't read encrypted traffic, so they can't fully take part in an ordinary encrypted mesh. Firmware 2.8 adds amateur regions for 2 m, 1.25 m and 70 cm, and signs messages instead of encrypting them.

Getting on air

1. Get a 915 MHz board that Meshtastic supports. The web flasher lists them. Fit the antenna before powering it up.
2. Flash the firmware from the web flasher in Chrome or Edge, choosing your board and a stable release. Many boards come with Meshtastic already installed.
3. Install the Meshtastic app (Android, iPhone or web) and pair over Bluetooth. Screens show the PIN; screenless boards default to 123456.
4. Set the region to US. A new node won't transmit until you do. Use the preset your local mesh uses.
5. Set the TX power to what your device's authorization covers, and decide on position sharing.
6. Say hello on the default channel, and look at the node list to see who's in range.

How Meshtastic passes messages on

Meshtastic uses managed flooding. Unlike MeshCore, every node relays by default, handhelds included. Before passing a message on, a node waits a moment; if it hears another node relay it first, it stays quiet. Nodes that heard the message weakly wait less, so the most distant ones tend to relay first. Each relay lowers the message's hop limit, which starts at 3 and can be set as high as 7. At 0, nobody passes it on.

Direct messages start the same way. Since firmware 2.6, once a reply comes back, the nodes on the way learn the next hop towards each other, and only that node relays later messages. If it goes quiet, the sender falls back to flooding on its last retry.

What a node does is set by its role:

Don't set a handheld or a home node to ROUTER. Badly placed routers relay everything, use up airtime and drain batteries. Talk to your local mesh first.

Channels and privacy

• The default channel (named after the preset, such as LongFast) uses a key everyone knows, AQ==, so anyone can read it.
• Private channels use a key you generate and share by QR code or link. Anyone with it can read the channel. Messages are encrypted with AES; firmware 2.8 adds an option to detect tampering, which every node on the channel has to turn on.
• Direct messages are encrypted with keys only the two nodes can work out, using each node's public and private key.
• Not hidden: the packet header, including who sent it, and anything sent on the default channel, such as your node name and, if you share it, your position.

A text message holds up to about 228 bytes. Up to firmware 2.7, Meshtastic shares your position by default if the node has GPS or your phone provides it. Firmware 2.8 keeps it private by default, with position and telemetry broadcasts off. Whichever you run, check the position settings in the app.

Range and antennas

Height and a clear view matter more than anything else. Mount the antenna vertically, clear of your body and metal, and keep coax short: 5 m (16 ft) of RG58 loses about 2.5 dB at 915 MHz. Stick to antennas your device's FCC grant lists.

When it doesn't work

Meshtastic isn't an emergency service and nobody is guaranteed to be listening. In an emergency, call 911.

Sources

• 47 CFR §15.247, §15.249, §15.5 and §97.113.
• Meshtastic docs: LoRa settings, presets, device roles, mesh algorithm, encryption, switching from LongFast and 2.8 notes.
• Meshtastic firmware source.

Checked November 2026. This is general information, not legal advice. See also Meshtastic UK, MeshCore USA and Meshtastic vs MeshCore.

Questions