Glossary

A list of terminology often used when discussing mesh and radio topics (US-centric):

• 2m/140 band: the band of spectrum from 144 MHz to 148 MHz, allocated to Amateur Radio Service use
• 33cm/915 band: the band of spectrum from 902 MHz to 928 MHz in the US, allocated primarily to unlicensed ISM use, which Meshtastic operates within
• 70cm/440 band: the band of spectrum from 420 to 450 MHz in the US, allocated to Amateur Radio Service use
• airtime: the amount of time a transmission requires from start to finish
• Alfa: a brand of antenna
• APRS: Automatic Packet Reporting System, a digital packet transmission used by amateur radio operators that also functions in a mesh fashion; traditionally operates in the 2m band, but has a new LoRa variant operating in the 70cm band
• attenuation: the decrease in signal strength caused by obstacles such as buildings, trees, bodies, poor connections, and so on
• backbone nodes: infrastructure nodes in key locations with reliable links to each other that form the core of a regional network, typically on towers or mountains
• bandwidth (BW): a continuous range of frequencies a signal occupies
• base (station): a station at a fixed location, often with substantial antenna or power capability
• BLE: Bluetooth Low Energy, a technology for connecting client devices like phones to mesh nodes
• building clutter: the attenuation caused by the general built environment in an area
• callsign: an identifier used by a station, often alphanumeric; used by the FCC to organize licensees
• channel: the feature Meshtastic uses to group messages, using encryption keys; also describes labeled frequencies in general RF contexts
• channel utilization: a measure of how much time a radio spends sending or receiving LoRa packets
• chirp: the fundamental unit of a LoRa transmission that sweeps across frequencies in the bandwidth of the signal
• client: a device and/or software used to connect with and control a node, and interact with the mesh; also a Meshtastic role that conditionally repeats packets
• CLIENT: a Meshtastic role that conditionally repeats packets after ROUTERs
• CLIENT_BASE: a Meshtastic role that conditionally repeats packets after ROUTERs, with additional behaviors intended for fixed nodes
• coding rate (CR): the amount of redundant bits included in a LoRa transmission, increasing signal resiliency at the cost of airtime
• dB: Decibel, a measure of signal power ratios
• dBi: a measure of antenna gain in dB with respect to a dipole antenna
• dBi: a measure of antenna gain in dB with respect to a theoretical isotropic radiator
• dBm: a measure of power in dB with respect to milliwatts, 30 dBm equals 1 Watt
• digipeater: an APRS node that repeats packets
• dipole: a type of antenna with two electrical radiators that operate at opposite ends of an alternating current
• duty cycle: the percentage of a given time window a radio spends transmitting, some jurisdictions limit this by law
• EIRP: Effective Isotropic Radiated Power, the final power output from an antenna after combining transmitted power, feed line loss, and antenna gain
• feed line: the path the signal takes from the transmitter to the antenna, often coaxial cable
• feed point: the point of the antenna the feed line connects to
• filter: a device used inline that reduces interference from signals on
• fixed node: a node installed in specific, unmoving location
• flash: the process of updating the firmware of the node
• flasher: the tool used to update firmware
• FRS: Family Radio Service, a channelized portion of UHF spectrum allocated for unlicensed use, “walkie talkies”
• gateway: a node that uplinks packets to, or downlinks from, MQTT
• GMRS: General Mobile Radio Service, a channelized portion of UHF spectrum licensed by the FCC
• ham: someone with an Amateur Radio License, aka Ham Radio (not an acronym or initialism)
• Heltec: a manufacturer of node hardware
• HT: Handheld Transceiver, a portable radio
• iGate: an APRS gateway
• infill nodes: infrastructure nodes that provides a second level of coverage and function to bridge street level with the backbone, typically on high rooftops
• ISM: Industrial, Scientific, and Medical; describes bands of spectrum dedicated to this generally unlicensed purpose
• LNA: low noise amplifier, use to increase receiver input
• LongFast (LF): one of the Meshtastic LoRa radio presets, sometimes combined with a frequency slot such as LF20 for the default slot
• LoRa: Long Range, a proprietary RF modulation technology that mesh nodes use to transmit signals to other nodes
• LoRaWAN: a networking protocol on top of LoRa typically used for collecting sensor data
• MC: MeshCore
• MediumFast (MF): one of the Meshtastic LoRa radio presets
• MediumSlow (MS): one of the Meshtastic LoRa radio presets
• mesh: a network of radio nodes that relay messages to propagate them
• mobile (station): a radio transceiver attached to or associated with a vehicle
• MQTT: a protocol for queuing and distributing messages; used by Meshtastic to aggregate packets over the internet
• MT: Meshtastic
• Muzi: a node manufacturer and parts seller
• narrow: when describing LoRa radio settings, typically refers to narrow bandwidths like the default MeshCore setting of 62.5 kHz
• net: a scheduled meeting of radio operators over RF, generally conducted by a designated controller
• node: a LoRa radio and microcontroller running Meshtastic or MeshCore firmware, the physical unit of a mesh
• N-type connector: a common weatherproof RF connector used for larger antennas, typically intended for base stations and outdoor installations and connected to node PCBs using pigtails and coaxial cable
• PA: power amplifier, used to increase transmitter power output
• packet: the base unit of data for Lora, each transmission consists of a complete packet that includes metadata describing how it should be routed, along with a payload
• PCB: printed circuit board
• pigtail: a short cable typically converting one type of connector to another, such as uFL to N-bulkhead
• portable (station): a radio transceiver made to be carried by hand, like a walkie-talkie
• preset: a particular set of radio parameters
• RAK: a manufacturer of node components
• repeater: in MeshCore, an infrastructure node role that repeats packets, typically placed in high locations; also a legacy, deprecated Meshtastic node role
• ROUTER: in Meshtastic, an infrastructure node role that repeats packets before other roles, typically placed in high locations
• ROUTER_LATE: in Meshtastic, an infrastructure node role that repeats packets after clients
• RF: “Radio Frequency” radiation or energy, the electromagnetic radio waves created by alternating current that are the medium of the mesh
• RP-SMA: A variant of SMA connector that inverts which threading has the pin and socket, originally used by manufacturers to comply with FCC rules in the early days of WiFi
• Rokland: a retailer of RAK hardware and other parts
• RSSI: Received Signal Strength Indicator, the power of an incoming signal typically expressed in dBm
• rubber duck: a style of short, flexible, often poor antenna, typically included with node kits and consumer grade radios
• RX: reception or receiver
• RTL-SDR: a popular brand and model of SDR
• SAW: Surface Acoustic Wave, usually referring to a type of bandpass filter that operates using this phenomenon
• SDR: Software Defined Radio, a type of radio that can be controlled by computer, often used to scan different frequencies
• Seeed: a manufacturer of node components
• ShortTurbo (ST): one of the LoRa radio presets
• (frequency) slot: a numeric label representing a specific center frequency for a Meshtastic node to use, based on dividing the ISM spectrum by a particular bandwidth, such as 20 for 906.875 MHz when using 250 kHz bandwidth
• SMA: a common type of RF connector used by smaller antennas or other components like filters, often connected to a PCB via pigtail but may be directly mounted
• SNR: Signal-to-Noise ratio, the strength of the signal relative to the strength of the background noise, typically given in dB and often negative for LoRa transmissions
• spread factor (SF): the amount of time used for each chirp in a LoRa transmission; higher spread factors increase resistance to noise but decrease data rate
• station: a radio transmitter and/or receiver with an associated identity or callsign
• (V)SWR: Voltage Standing Wave Reflection, a measure of how closely the antenna resonates to a particular frequency and consequently how efficiently it radiates energy instead of converting it to heat; 1 is the ideal value, above 2 is considered poor
• transceiver: a radio capable of both transmit and receive
• tropospheric ducting / 🌈🦆: a phenomenon where atmospheric conditions refract radio signals and cause them to travel much farther than usual
• tuning: the process of adjusting an antenna to achieve resonance at a particular frequency
• TX: transmission or transmitter
• U.FL/IPEX: a type of miniature RF connector used by many node PCBs
• UHF: Ultra High Frequency, the spectrum from 300 MHz to 3 GHz
• VHF: Very High Frequency, the spectrum from 30 MHz to 300 MHz
• VNA: Vector Network Analyzer, a tool to measure characteristics of antennas and other RF components
• whip: a style of antenna, usually thin and flexible, popular for handheld and portable nodes