Technical Glossary
March 16, 2026 · View on GitHub
Purpose: Definitions of technical terms used in Mesh Community Planner Audience: End users, community organizers, non-technical planners WCAG 2.2 AAA Compliance: Satisfies 3.1.3 (Unusual Words) and 3.1.4 (Abbreviations)
A
Antenna
Definition: A device that transmits and receives radio signals. In mesh networks, the antenna converts electrical signals into radio waves and vice versa.
Types:
- Omnidirectional: Radiates signal equally in all directions (360°)
- Directional: Focuses signal in one direction for longer range
Related: Antenna Height, Gain
Antenna Height
Definition: The vertical distance from the ground to the antenna, measured in meters or feet. Higher antennas typically achieve better line-of-sight and longer range.
Typical Values:
- Ground level: 0-3m (portable devices)
- Rooftop: 6-15m (residential installations)
- Tower: 20-100m (high-altitude installations)
Related: Elevation, Line-of-Sight
API (Application Programming Interface)
Definition: A set of rules and protocols that allows different software systems to communicate. In Mesh Community Planner, the backend provides a REST API that the frontend uses to manage plans, nodes, and analysis.
Articulation Point
Definition: A node in a mesh network whose removal would disconnect the network into separate parts. Also called a "single point of failure."
Example: If removing one relay node causes 5 other nodes to lose connection to the gateway, that relay is an articulation point.
Why It Matters: Networks should minimize articulation points for resilience.
Related: Topology, Resilience
B
BOM (Bill of Materials)
Definition: A comprehensive list of all hardware and equipment needed to build the planned mesh network, including quantities and estimated costs.
Includes:
- Node devices (gateways, relays, clients)
- Antennas and cables
- Power supplies (solar panels, batteries)
- Mounting hardware
- Installation materials
Related: Cost Estimate, Hardware
Broadband
Definition: High-speed internet access, typically ≥25 Mbps download. Mesh networks can provide internet access when connected to a broadband gateway.
Note: LoRa mesh networks are not broadband—they provide low-bandwidth data for sensors and messages, not internet streaming.
C
Cache
Definition: Temporary storage of data to speed up future access. Mesh Community Planner caches map tiles and terrain data to work offline.
Benefits:
- Faster loading (no re-download)
- Offline functionality
- Reduced bandwidth usage
Related: Offline Mode, Storage
Client Node
Definition: An endpoint device in a mesh network that sends and receives data but doesn't relay traffic for other nodes.
Examples: Sensors, handhelds, IoT devices
Related: Gateway, Relay, Node
Coverage
Definition: The geographic area where a mesh network provides signal. Typically measured as a percentage of the target area with adequate signal strength.
Types:
- Predicted coverage: Calculated via propagation models
- Actual coverage: Measured via real-world testing
Related: Propagation, Signal Strength
D
dBm (Decibels Milliwatt)
Definition: A unit of measurement for radio signal power, expressed in decibels relative to 1 milliwatt.
Common Values:
- 0 dBm = 1 mW (very low power)
- 14 dBm = 25 mW (typical LoRa)
- 20 dBm = 100 mW (common outdoor)
- 27 dBm = 500 mW (high power)
- 30 dBm = 1 W (legal limit in many regions)
Key Concept: Every 3 dBm doubles the power (e.g., 14 dBm → 17 dBm = 2x power).
Related: TX Power, Signal Strength
Duty Cycle
Definition: The percentage of time a radio can transmit, imposed by regulations to prevent spectrum congestion.
Example: 1% duty cycle = can transmit for 36 seconds per hour maximum.
Typical: LoRa in unlicensed bands often has 1-10% duty cycle limits.
E
Elevation
Definition: Height above sea level, measured in meters or feet. Elevation affects line-of-sight and propagation.
Examples:
- Sea level: 0m
- Denver, CO: 1,609m (5,280 ft - "Mile High City")
- Mount Everest: 8,849m
Note: Elevation is geographic (terrain), while antenna height is relative to ground.
Related: Antenna Height, Terrain
F
Frequency
Definition: The number of radio wave cycles per second, measured in Hertz (Hz) or megahertz (MHz). Different frequencies have different propagation characteristics.
LoRa Bands:
- 915 MHz: North America (902-928 MHz ISM band)
- 868 MHz: Europe (863-870 MHz)
- 433 MHz: Asia/Africa
Key Concept: Lower frequencies (e.g., 433 MHz) travel farther but require larger antennas. Higher frequencies (e.g., 2.4 GHz) have higher bandwidth but shorter range.
Related: LoRa, Spectrum
Fresnel Zone
Definition: An elliptical area around the direct line between two antennas where radio waves can interfere with each other. Obstructions in the Fresnel zone can degrade signal.
Clearance Guidelines:
- 100% clear: Excellent signal (no obstructions)
- 60-99% clear: Good signal (minor obstructions OK)
- 40-59% clear: Marginal signal (noticeable degradation)
- <40% clear: Poor signal (may not work reliably)
Why It Matters: Even if you have line-of-sight, trees or buildings in the Fresnel zone can weaken the signal due to diffraction.
Related: Line-of-Sight, Propagation, Diffraction
FSPL (Free Space Path Loss)
Definition: A radio propagation model that calculates signal loss in ideal conditions (no terrain, obstacles, or interference). Assumes clear line-of-sight in a vacuum.
Formula: FSPL (dB) = 20 log₁₀(distance) + 20 log₁₀(frequency) + 32.45
Pros: Fast, simple, no API required
Cons: Overly optimistic—doesn't account for real-world terrain or obstacles
Compare: ITM/Longley-Rice (terrain-aware)
Related: Propagation, Signal Loss
G
Gateway
Definition: The central node in a mesh network that connects to the internet or backhaul network. All data from client and relay nodes eventually routes to a gateway.
Key Role: Gateways are critical—if the gateway fails, the entire network loses internet connectivity (but local mesh communication may continue).
Typical Setup:
- High antenna (15-30m)
- High TX power (27-30 dBm)
- Reliable power (grid or large solar)
- Backhaul connection (fiber, cellular, satellite)
Related: Relay, Client, Backhaul
Geocoding
Definition: Converting human-readable addresses into geographic coordinates (latitude/longitude) or vice versa.
Examples:
- "123 Main St, Denver, CO" → (39.7392° N, 104.9903° W)
- (37.7749° N, 122.4194° W) → "San Francisco, CA"
Used by: Address search bar (via Nominatim / OpenStreetMap)
I
ISM Band (Industrial, Scientific, Medical)
Definition: Unlicensed radio frequency bands reserved for non-commercial use. LoRa operates in ISM bands.
Common ISM Bands:
- 433 MHz (Europe, Asia)
- 868 MHz (Europe)
- 915 MHz (North America)
- 2.4 GHz (worldwide - WiFi, Bluetooth)
Advantage: No license required Disadvantage: Shared with other devices, potential interference
ITM (Irregular Terrain Model)
Definition: A sophisticated radio propagation model that accounts for terrain, elevation changes, and obstacles. Used by Signal-Server for terrain-aware propagation analysis.
More Accurate Than: FSPL (which assumes flat, obstacle-free terrain)
Related: Terrain, Propagation
L
Latitude
Definition: Geographic coordinate measuring north-south position, expressed in degrees from -90° (South Pole) to +90° (North Pole).
Examples:
- Equator: 0°
- North Pole: 90° N
- South Pole: 90° S
- San Francisco: 37.77° N
Related: Longitude, Coordinates
Line-of-Sight (LOS)
Definition: A clear, unobstructed path between two antennas. Radio signals travel best with line-of-sight.
Types:
- Optical LOS: Can see one antenna from the other (visible)
- Radio LOS: No terrain blocking the Fresnel zone (may not be visible)
Key Concept: You can have optical LOS but still poor signal if the Fresnel zone is obstructed.
Related: Fresnel Zone, Terrain Profile
Longitude
Definition: Geographic coordinate measuring east-west position, expressed in degrees from -180° (West) to +180° (East).
Examples:
- Prime Meridian (Greenwich, UK): 0°
- International Date Line: ±180°
- New York: 74° W (-74°)
- Tokyo: 139° E (+139°)
Related: Latitude, Coordinates
LoRa (Long Range)
Definition: A wireless communication technology designed for long-range, low-power, low-bandwidth data transmission. Ideal for IoT sensors, environmental monitoring, and emergency communications.
Characteristics:
- Range: 2-15 km (varies by environment)
- Bandwidth: ~0.3-50 kbps (very low—not for video/voice)
- Power: Extremely low (battery life of months/years)
- Frequency: 433/868/915 MHz (unlicensed ISM bands)
Use Cases:
- Sensor networks (temperature, air quality)
- Asset tracking
- Smart agriculture
- Emergency alerts
- Mesh messaging
Related: Mesh Network, ISM Band
LoRaWAN
Definition: A network protocol for LoRa that uses a star topology (all devices connect directly to a gateway). Different from LoRa mesh.
Key Difference: LoRaWAN = star (no device-to-device relay), Mesh = devices can relay for each other.
M
Mesh Network
Definition: A network topology where nodes can relay data for each other, creating multiple paths from source to destination. More resilient than star networks.
Advantages:
- Redundancy (multiple paths)
- Extended range (relay through multiple hops)
- Self-healing (reroutes if a node fails)
Disadvantages:
- More complex routing
- Higher latency (more hops)
- Bandwidth shared across hops
Related: Topology, Relay
MHz (Megahertz)
Definition: One million cycles per second. Unit for measuring radio frequency.
Examples:
- FM radio: 88-108 MHz
- LoRa (North America): 902-928 MHz
- WiFi: 2,400-2,483 MHz
Related: Frequency
N
Node
Definition: Any device in the mesh network. Can be a gateway, relay, or client.
Total Nodes: Count of all devices in the network.
Related: Gateway, Relay, Client
P
Path Loss
Definition: Reduction in signal strength as radio waves travel through space. Measured in decibels (dB).
Factors:
- Distance (inverse square law)
- Frequency (higher frequency = more loss)
- Obstacles (trees, buildings, terrain)
- Atmospheric conditions
Related: FSPL, Propagation
Propagation
Definition: The behavior of radio waves as they travel from transmitter to receiver. Affected by distance, terrain, frequency, and obstacles.
Models:
- FSPL: Simple, ideal conditions
- ITM (Longley-Rice): Terrain-aware, realistic
Related: Coverage, FSPL
R
Radio Horizon
Definition: The maximum distance a radio signal can travel before Earth's curvature cuts off line-of-sight, even in the absence of terrain obstacles. Shown in each node's detail panel as a function of antenna height.
Formula: d (km) ≈ 3.57 × √h, where h is antenna height in meters. The effective radio horizon between two nodes is the sum of each node's individual horizon distance.
Example Values:
- 1m antenna height → ~3.6 km horizon
- 3m → ~6.2 km
- 10m → ~11.3 km
- 30m → ~19.5 km
- 100m → ~35.7 km
Key Concept: The radio horizon is a theoretical upper bound. Real-world range is further limited by terrain obstructions, Fresnel zone clearance, and receiver sensitivity. Coverage analysis accounts for terrain and will show a tighter limit in hilly areas.
Related: Antenna Height, Line-of-Sight, Fresnel Zone
Relay Node
Definition: An intermediate node that receives signals from other nodes and retransmits them, extending network range and providing redundancy.
Key Role: Relays enable multi-hop mesh networks, allowing data to reach nodes beyond direct gateway range.
Typical Setup:
- Medium antenna height (8-15m)
- Medium TX power (20-24 dBm)
- Solar powered (for remote locations)
Related: Gateway, Client, Mesh
Resilience
Definition: A network's ability to maintain connectivity despite node failures. High resilience means multiple paths between nodes.
Metrics:
- Articulation points: Fewer is better
- Redundant paths: More is better
- Node degree: Nodes with many connections increase resilience
Related: Articulation Point, Topology
RSSI (Received Signal Strength Indicator)
Definition: Measurement of received radio signal power at the antenna, expressed in dBm. Higher (less negative) is better.
Typical Values:
- -30 dBm: Excellent (very close)
- -60 dBm: Good (typical indoor)
- -80 dBm: Fair (typical outdoor)
- -100 dBm: Weak (edge of coverage)
- -120 dBm: Minimum detectable signal
Key Concept: RSSI is negative. -50 dBm is stronger than -90 dBm.
Related: dBm, Signal Strength, SNR
S
Signal Strength
Definition: The power of the received radio signal, typically measured as RSSI in dBm.
Related: RSSI, dBm
SNR (Signal-to-Noise Ratio)
Definition: The ratio of desired signal power to background noise power, expressed in decibels (dB). Higher SNR means better signal quality.
Typical Values:
-
10 dB: Excellent
- 5-10 dB: Good
- 0-5 dB: Marginal
- <0 dB: Unusable (noise stronger than signal)
Key Concept: SNR is more important than RSSI alone. A weak signal with low noise (high SNR) is better than a strong signal with high noise (low SNR).
Related: RSSI, Noise
Solar Power
Definition: Using photovoltaic panels to convert sunlight into electricity for powering nodes. Essential for remote installations without grid power.
Components:
- Solar panel (PV array)
- Charge controller
- Battery (for night/cloudy days)
- DC-DC converter (voltage regulation)
Sizing: Panel and battery sized for:
- Daily energy consumption (W·h)
- Days of autonomy (cloudy days without sun)
- Geographic location (hours of sunlight per day)
Related: Power, Battery
T
Terrain
Definition: The physical features of the land surface, including elevation changes, hills, valleys, and obstacles. Terrain significantly affects radio propagation.
Data Sources:
- SRTM (Shuttle Radar Topography Mission) - 30m resolution
- ASTER - 30m resolution
- Lidar - <1m resolution (high accuracy)
Related: Elevation, Propagation
Terrain Profile
Definition: A cross-sectional view of the terrain between two points, showing elevation changes and potential obstacles.
Use: Identify hills, valleys, or structures that may block line-of-sight.
Related: Line-of-Sight, Fresnel Zone
Topology
Definition: The arrangement and interconnection of nodes in a network. Shows which nodes can communicate directly.
Types:
- Star: All nodes connect to central gateway (not mesh)
- Mesh: Nodes interconnected with multiple paths
- Tree: Hierarchical structure
Related: Mesh Network, Articulation Point, Resilience
TX Power (Transmit Power)
Definition: The amount of radio power a transmitter outputs, measured in dBm or milliwatts (mW).
Legal Limits:
- Most regions: 30 dBm (1 W) maximum for unlicensed ISM bands
- Some regions: Lower limits (e.g., 14 dBm)
Trade-off:
- Higher TX power = longer range, more battery drain
- Lower TX power = shorter range, better battery life
Related: dBm, Power
U
Uplink / Downlink
Definition:
- Uplink: Data transmission from a node to the gateway
- Downlink: Data transmission from the gateway to a node
Related: Gateway
W
WCAG (Web Content Accessibility Guidelines)
Definition: International standards for making web content accessible to people with disabilities.
Levels:
- A: Basic accessibility
- AA: Industry standard (required for many regulations)
- AAA: Highest level (enhanced accessibility)
Mesh Community Planner: WCAG 2.2 AA compliant (85/100 score), working toward AAA.
Abbreviations Reference
| Abbreviation | Full Term | Quick Definition |
|---|---|---|
| API | Application Programming Interface | Software communication protocol |
| BOM | Bill of Materials | List of hardware and costs |
| dBm | Decibels Milliwatt | Radio power measurement |
| FSPL | Free Space Path Loss | Ideal propagation model |
| IoT | Internet of Things | Connected sensors/devices |
| ISM | Industrial, Scientific, Medical | Unlicensed radio bands |
| ITM | Irregular Terrain Model | Terrain-aware propagation |
| LoRa | Long Range | Low-power wireless technology |
| LOS | Line-of-Sight | Clear path between antennas |
| MHz | Megahertz | Million cycles per second |
| RSSI | Received Signal Strength Indicator | Signal power measurement |
| SNR | Signal-to-Noise Ratio | Signal quality measurement |
| SRTM | Shuttle Radar Topography Mission | Terrain data source |
| TX | Transmit | Sending radio signals |
| WCAG | Web Content Accessibility Guidelines | Accessibility standards |
Usage in HTML
To make abbreviations accessible, use the <abbr> tag with a title attribute:
<abbr title="Long Range">LoRa</abbr> operates in the
<abbr title="Industrial, Scientific, Medical">ISM</abbr> band at
<abbr title="megahertz">MHz</abbr> frequencies.
Screen readers will announce the expansion when encountering abbreviated terms.
Related Documentation
- USERGUIDE.md: Step-by-step usage instructions
- TROUBLESHOOTING.md: Common issues and solutions
- SETTINGS-TOOLTIPS.md: In-app help text
- WIZARD-TOOLTIPS.md: Node wizard field explanations
Maintained by: W5 (QA, Accessibility & Documentation) Last Updated: 2026-02-08 WCAG 2.2 AAA Compliance: ✅ Satisfies 3.1.3 (Unusual Words) and 3.1.4 (Abbreviations)
End of Glossary