Title: Scanning
Description: Monitor SubGHz radio activity across frequency bands
URL: /v2.1/subghz/scanning/
Version: v2.1
Section: SubGHz
Search index: /search-index.json

# Scanning

> Monitor SubGHz radio activity across frequency bands

## On this page

- [Prerequisites](#prerequisites)
- [Scanning for signals](#scanning-for-signals)
- [On-device UI](#on-device-ui)
- [Command line](#command-line)
- [Frequency bands](#frequency-bands)
- [Signal strength visualization](#signal-strength-visualization)
- [Notes](#notes)
- [Troubleshooting](#troubleshooting)

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Monitor radio activity across 64 channels in real-time to detect signals on supported frequency bands.
## Prerequisites
- GhostESP device with CC1101 SubGHz hardware (see [Hardware Support](/v2.1/subghz/hardware/))
- Device powered on with antenna attached
## Scanning for signals
### On-device UI
- Open Menu → SubGHz → Capture.
- Select Start from the popup menu to begin scanning.
- The device will scan the current frequency band.
- Signal strength is displayed across 64 channels.
- Use Cycle Frequency to switch between bands (315, 390, 433.92, 868.35, 915 MHz).
- Press Back to stop scanning.
### Command line
# Start scanning on current frequency
subghz start
# Stop scanning
subghz stop
# Pause/resume scanning
subghz pause
subghz resume
# Cycle to next frequency band
subghz cycle_freq
# Check scanner status
subghz status
## Frequency bands
The scanner supports five common SubGHz bands. Cycle through them to find the one used by your target device:
- 315 MHz - Common in North America for garage doors and remote controls
- 390 MHz - Used by some security systems and remote controls
- 433.92 MHz - Most common worldwide for garage doors, gates, and wireless sensors
- 868.35 MHz - European standard for remote controls and alarm systems
- 915 MHz - North America ISM band for various devices
## Signal strength visualization
The scanner displays signal strength across 64 channels within the selected band. Higher bars indicate stronger signals. Use this to:
- Identify active channels
- Find the frequency of a transmitting device
- Verify signal reception before capturing
## Notes
- SubGHz scanning requires CC1101 hardware with CONFIG_HAS_SUBGHZ enabled. CONFIG_HAS_SUBGHZ_REMOTE only enables a display-only remote UI that routes commands to a peer — it does not enable scanning itself.
- Scanning is mutually exclusive with other SubGHz operations; starting a new scan will stop any ongoing capture or transmission.
- Signal strength is displayed as relative levels; higher values indicate stronger signals.
- Some devices transmit intermittently; leave the scanner running for several minutes to detect periodic signals.
## Troubleshooting
- No signals detected: Try different frequency bands or move closer to the target device. Ensure the antenna is properly connected.
- Scanner fails to start: Check that your device has SubGHz hardware enabled. Verify SPI pin configuration in the build config.
- Weak signals: Improve antenna placement or use a higher-gain antenna compatible with the CC1101 frequency range.