MeshCore glossary

The words you will run into, in plain English.

Advert: A signed broadcast of a node's name, public key and (optionally) position that lets other nodes add it as a contact. Adverts are not encrypted.
BLE: Bluetooth Low Energy, the Bluetooth link a companion radio uses to talk to the phone app.
BW (bandwidth): How wide a slice of radio spectrum each transmission uses; the US preset uses 62.5 kHz.
Channel: A group chat secured by a shared key, where everyone who has the key can read and post.
Companion: Your personal radio, running firmware that connects to the MeshCore app over Bluetooth or USB.
Companion Repeat Mode: An optional setting that lets a companion relay messages, limited to special off-grid radio settings.
Contact: A saved node in your app; you and another user must add each other as contacts before private messages work.
CR (coding rate): How many extra error-correction bits each packet carries; the FAQ suggests CR5 for stable links.
Flasher: The web tool at flasher.meshcore.io that installs MeshCore firmware on a radio over USB.
Flood advert: An advert that repeaters pass along so it reaches beyond direct range. By default, repeaters stop forwarding adverts after 8 hops.
Hashtag channel: A public group channel with a name that starts with #, such as #test, which anyone on the mesh can create.
Hop: One step a packet takes when a repeater passes it along.
ISM band: A shared radio band; in the US, MeshCore runs in the 902 to 928 MHz part of it.
LoRa: A long-range, low-power radio technology that MeshCore radios use to send packets.
MQTT: A message broker protocol that some nodes use to send the LoRa traffic they hear to an internet server for maps and analysis tools.
Observer: A node that reports the packets it hears to an analyzer service, helping map coverage.
Path (route): The list of repeaters a message travels through; MeshCore learns it from the first delivery and reuses it for later messages.
Path hash (prefix bytes): The first 1, 2 or 3 bytes of a repeater's public key, used to name that repeater inside a packet's path.
Public channel: The default channel every MeshCore user starts with, which anyone on the mesh can read.
Region (scope): A named area set on repeaters, so a sender can limit how far a flooded message travels.
Repeater: A node, usually mounted high, that forwards packets to extend the network's range.
Room server: A node that stores posts like a small bulletin board, so users can read messages they missed.
Sensor: A node type for remote telemetry and alerts that you build and customize from example code.
SF (spreading factor): How long each radio symbol is stretched out; lower values send faster, and the US preset uses SF7.
Zero-hop advert: An advert that only radios in direct range receive, because repeaters do not pass it on.

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