+++
title = "LoRa Scanner"
description = "Listen to the radio: every packet it hears, a survey of signal strength from 863 to 870 MHz, and captures for Wireshark. It only listens."
weight = 2
[extra]
tag = "LoRa Scanner"
screens = ["sniffer.png", "sweep.png"]
+++

The Scanner uses the **Cap LoRa-1262**. It **never transmits**: it listens and shows.

## Sniffer

The first view lists what the radio hears, newest first: the time, the RSSI (signal strength, in dBm) and the SNR (signal over noise, in dB). For a **Meshtastic** packet it also shows the sender and the receiver (the last four hex digits of their numbers) and the number of hops.

| Key | Does |
|---|---|
| <kbd>Enter</kbd> | The details of a packet: the Meshtastic header, which is never encrypted, and a hex dump |
| <kbd>p</kbd> | Picks one of the 7 Meshtastic presets allowed in EU868 (LongFast by default) |
| <kbd>c</kbd> | Starts or stops a **capture** |
| <kbd>Tab</kbd> | Switches to the Sweep |

The Scanner shows the header and the bytes; it does not decrypt the message itself, which Meshtastic encrypts with the channel's key.

## Capture

A capture records packets into a **pcap** file with LoRaTap headers in `/captures/lora/` on the SD card, to open in Wireshark. It keeps recording with the App closed (the Status Bar shows `CAP`); the radio sleeps when the App is not open and no capture is running. Captures are never deleted unless you ask, in the [Storage App](/guide/storage/), which can also show a pcap's packets on the device.

## Sweep

<kbd>Tab</kbd> switches to the Sweep: the signal strength across **863 to 870 MHz** in 100 kHz steps, drawn as bars with a mark at each peak, and a waterfall under them. The frequency the Sniffer listens on is marked. The Sniffer is paused during a Sweep and picks up where it was. The Status Bar shows `SW`.

## The GNSS receiver raises the noise

The GNSS receiver on the same Cap makes the radio's noise floor about **8 dB** worse while it runs. **Settings → Pause GNSS for LoRa** (off by default) puts the receiver on standby while the radio listens, except while a Track is being recorded.