What Is MeshCore?

The short version: LoRa is the radio technology, MeshCore is the software that runs on the radio and turns a pile of separate devices into a network, and Nelos is the app that turns that network into something you'd actually want to use - the part you see, touch, and recognize as "your team". Three layers, but only the top one is what you deal with day to day.

The three layers

It's worth being precise about these, because shop listings often blur them together.

• LoRa is the radio technology - the way the signal physically travels through the air. It's designed to go a long way on very little power by sending data slowly, which suits short messages and location coordinates. LoRa uses different frequency bands in different parts of the world, so a device is made for a specific region. On its own, LoRa is just a way to move bits from one radio to another. The guide what a LoRa mesh radio is covers this layer from scratch.
• MeshCore is the firmware and protocol that runs on the radio. It's the part that decides how a message finds its way from one device to the next, handles relaying through repeaters - what makes it a "mesh" - keeps the group's traffic encrypted so it isn't readable by every device that passes it along, and defines the roles a device can play. MeshCore is an open-source project; it isn't owned by any one app maker, and several different apps can talk to a MeshCore radio.
• The app is the layer on your phone: the message screen, the map, the contact list, the settings. It connects to the radio over Bluetooth and shows you what the network is doing. Nelos is one such app, aimed at families and groups; there are others aimed at different users.

What a "MeshCore-compatible device" is

A MeshCore-compatible device is simply a LoRa radio that runs the MeshCore firmware. Some devices ship with it already installed and work out of the box; others ship with different firmware and need MeshCore flashed onto them once, using the project's web flasher, before an app will recognise them. Either way, the device also has to be the right version for your region's LoRa band. The devices guide marks which is which.

The roles a device can play

In a MeshCore network, each device is a node, and a node can be set up for different jobs:

• Companion radio - a handheld paired to a phone over Bluetooth. This is what each person in a group carries; the phone is the interface, the radio does the sending and receiving. By default it doesn't relay traffic for other devices.
• Repeater - a device left running at a high point that does nothing but relay for the others, extending the network's reach. Whether you need one is covered in do you need a LoRa mesh repeater.
• Tracker - a small node with GPS and no phone attached that reports its own location when the app asks for it - useful for a child, a pet, or gear.

Many handheld devices with GPS can be used in more than one role, so you don't necessarily buy separate hardware for each.

How the mesh relaying works

If two devices are close enough, they talk directly. If they're too far apart, the message needs a relay in between: a repeater, or a radio or tracker with Companion Repeater mode switched on. Ordinary companion radios don't forward messages for each other by default, so a spread-out group stays connected only as far as direct range and its relays reach - which is why a repeater at a good vantage point can join parts of a group that otherwise couldn't reach each other.

Trackers on MeshCore

MeshCore isn't only for people with phones. A small GPS tracker running MeshCore firmware can ride on a dog's collar or in a child's backpack, and Nelos asks it for its position over your radio - no SIM, no cell service. That request-and-reply pattern is what features like Find Mode and Safe Zones are built on. How LoRa GPS tracking works explains it, and the SenseCAP T1000-E guide walks through a ready-made tracker.

Why compatible hardware matters

Your phone app speaks to the radio over Bluetooth in MeshCore's "language". A radio running a different mesh firmware won't understand a MeshCore app, and vice versa - so the device has to be running MeshCore, not just any LoRa firmware. And because LoRa bands are regional, a radio bought for another region may not be legal or may not connect with the rest of your group's devices. When in doubt, check the region and the firmware before buying.

MeshCore vs LoRa, in one line

LoRa is the road. MeshCore is the traffic rules and the vehicles that use it. The app is the seat you're sitting in. You need all three for the trip to work.

A note on other protocols

MeshCore isn't the only open-source LoRa mesh protocol - Meshtastic is another, separate one. They aren't interoperable: a given radio generally runs one or the other, and an app built for one won't talk to a device running the other. This article is just about understanding MeshCore itself; for a closer look at Meshtastic and who it suits, see goTenna Mesh vs Meshtastic.

Where Nelos fits

Nelos is a consumer-oriented app for MeshCore radios. It connects to a compatible radio over Bluetooth and gives you group messaging, everyone's latest location on a worldwide offline map, device trackers, and a "Need Help" button - in an interface built for families and outdoor groups rather than for configuring hardware. Nelos is free, needs no account, and did not create MeshCore - it's an independent app that uses it.

If you've got a radio and want to start, the devices guide confirms whether yours is ready or needs flashing, and Getting Started covers pairing it and creating a group. For the wider picture of how this fits among the other ways to communicate off-grid, see the off-grid communication guide.