Glossary
Advert (MeshCore): a broadcast announcing a node so others can find it. Repeaters advertise every 12 hours by default.
AES: the encryption standard used for mesh messages. AES-128 and AES-256 differ in key length.
Bandwidth (BW): how wide a slice of spectrum a LoRa signal uses, in kHz. Wider is faster; narrower reaches farther.
Channel (Meshtastic): a named group with its own key. Channel 0 is the primary channel and sets your frequency slot; channels 1–7 are secondary.
Coding rate (CR): how much error correction LoRa adds, from 4/5 to 4/8.
Companion radio (MeshCore): your personal radio, paired with the MeshCore app. It doesn’t relay others’ messages.
dBi: antenna gain compared with an ideal antenna that radiates equally in every direction.
dBm: power on a log scale. 30 dBm is 1 watt; every 3 dB roughly doubles power.
Duty cycle: the share of time a radio may transmit. Limited to 10% in the EU 868 band; not limited in the US band.
EIRP: effective radiated power, meaning transmit power plus antenna gain minus cable loss.
Firmware: the software on the radio. Meshtastic and MeshCore are both firmware.
Flooding: relaying a message by having radios rebroadcast what they hear.
Fresnel zone: the football-shaped region around the straight line between two antennas that needs to be mostly clear for a strong link.
Gateway: a node that links the mesh to the internet, usually over MQTT.
Hop / hop limit: one relay step. The hop limit caps how many relays a message may take.
ISM band: frequencies set aside for license-free devices; 902–928 MHz in the US.
Licensed mode (Meshtastic): ham-radio mode, with no encryption and your call sign sent.
Link budget: how much signal loss a link can survive, in dB. Higher means more range.
LoRa: the long-range, low-power radio modulation made by Semtech.
LoRaWAN: a different networking standard for sensors talking to internet gateways. Not used by Meshtastic or MeshCore.
MQTT: a lightweight messaging protocol used to link meshes to internet servers.
nRF52 / ESP32: the two common processor families. nRF52 boards use much less power; ESP32 boards add Wi-Fi.
Node: any radio on the mesh.
Path (MeshCore): the list of repeaters a message takes, learned from the first exchange.
Preset: a named bundle of LoRa settings (spreading factor, bandwidth, coding rate), such as LongFast.
PSK: pre-shared key, the secret key for a channel.
Repeater: a fixed node that relays traffic for everyone.
Role (Meshtastic): how a node behaves, such as CLIENT, CLIENT_MUTE or ROUTER.
Room server (MeshCore): a node that stores posts like a message board and catches users up when they log in.
SMA / RP-SMA: common antenna connectors. They look alike but don’t mate with each other.
SNR: signal-to-noise ratio. How far a signal stands out above the background noise.
Spreading factor (SF): how long each LoRa chirp lasts. Higher reaches farther but is slower.
SX1262: Semtech’s common LoRa radio chip in modern boards.
UF2: a firmware file you drag onto an nRF52 or RP2040 board to flash it.