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title: How the Meshtastic Signal Meter Works

parent: User Guide

nav_order: 15

last_updated: 2026-08-30

description: How the signal meter rates quality from SNR relative to the LoRa modem preset — spread spectrum, presets, and what the bars really mean.

aliases:

• signal

• signal-meter

• snr

• rssi

The Meshtastic signal meter — the bars or status color next to a node — is calculated differently from the bars on a cell phone or Wi-Fi router. This page explains what it measures and why the same reading can mean something different on another preset.

Every time the LoRa radio receives a message, it reports two measurements:

• RSSI (Received Signal Strength Indicator) — the raw power hitting the antenna.

• SNR (Signal-to-Noise Ratio) — how far the signal stands above the background noise.

│ 💡 Tip: Think of RSSI as how loud a friend is talking and SNR as how easily you can pick their

│ voice out of the noise in the room. A friend shouting at a rock concert can be loud (high RSSI)

│ yet unintelligible (bad SNR), while a whisper in a quiet library is faint (low RSSI) yet

│ perfectly clear (great SNR).

Standard radios such as FM or Wi-Fi lose a signal to static once the background noise is louder than it (a negative SNR). LoRa's spread spectrum modulation lets the radio pull a signal out of the noise even when the noise is louder, so negative SNR values are common and expected in Meshtastic — for example, −10 dB means the signal is 10 decibels weaker than the background noise.

Each modem preset has an SNR limit: the lowest SNR at which that preset can still decode a message. Slower presets tolerate a weaker, noisier signal (a more negative limit, longer range); faster presets need a stronger signal (a less negative limit, shorter range).

The app rates signal quality (None, Bad, Fair, or Good) from SNR alone, measured against the active preset's SNR limit. It does not factor in RSSI: without knowing the local noise floor, RSSI alone cannot say whether a signal is decodable. RSSI is still available — on the node detail screen and in the metrics charts.

Because the rating is relative to the preset, the same SNR rates differently on different presets. An SNR of −16 dB rates Good on Long Fast (SNR limit −17.5 dB) but None on Short Fast (SNR limit −7.5 dB). Let T383838limit be the active preset's SNR limit:

The icon never goes blank, so count the bars carefully: a single bar means None, not a weak but usable link, and Good is a solid wedge rather than a set of bars. A gray three-bar icon labeled Unknown is a different state again — the packet carried no SNR measurement at all, which is not the same as measuring one and finding it too weak.

│ ℹ️ Note: Traceroute hop colors use fixed thresholds (−7 dB / −15 dB); the per-node signal meter

│ uses the preset-relative rating instead.

A great RSSI paired with a one- or two-bar rating (None or Bad) points to local interference, not distance. A cheap power supply, a noisy computer, or a nearby transmitter can create enough static to drown out an otherwise strong signal.

In the app, signal data appears in several places:

• Node list — a signal-bars icon, shown only for nodes your radio heard directly. A node reached through a relay shows its hop count instead, because the SNR your radio measured describes the last hop, not the whole path

• Node detail — SNR, RSSI, and the quality word in the Details card at the top of the screen

• Traceroute — per-hop signal quality for each relay node

• Signal Quality — historical SNR and RSSI data in the metrics charts

!Node list entry showing a Good signal rating: 12.5 dB SNR, −42 dBm RSSI, and the green signal-strength icon

• Nodes — where signal bars appear in the node list

• Node Metrics — SNR/RSSI history and the per-node signal quality reference

• Settings — Radio & User — modem presets and their SNR limits