SCAN CHANNELS: Find Wireless Activity

Use POOM SCAN CHANNELS to compare Wi-Fi and IEEE 802.15.4 packet activity before choosing a channel for deeper analysis.

Black-and-white pixel-art comic explaining why POOM scans wireless channels before a deeper packet capture. View full screen
SCAN CHANNELS: Find the Traffic Before You Capture

The comic explains that wireless traffic is not distributed evenly across every channel. POOM can scan first to locate busy channels, observe airtime competition, troubleshoot crowded Wi-Fi, choose a cleaner channel on a network you manage, and compare RF activity across places or times before beginning a deeper capture.

POOM lets you explore the radio environment through two different views:

  • Wi-Fi — scans the Wi-Fi bands and channels enabled by the current firmware, band mode, and regulatory configuration.
  • IEEE 802.15.4 — scans the 2.4 GHz channels used by technologies such as Zigbee and Thread.
What this measurement means: POOM ranks decodable packets it receives; it is not a laboratory spectrum analyzer. It cannot measure every RF energy source, duty cycle, retry condition, or non-Wi-Fi interferer. Treat packet share as an activity indicator, not a complete channel-utilization measurement.

Scanner procedure

  1. Open THE BEAST → SCAN CHANNELS.
  2. Use the navigation arrows to select Wi-Fi or IEEE 802.15.4.
  3. Press A to begin capturing and counting packets in real time.
  4. Let the same measurement window run each time you compare two locations or configurations.

The question to answer is: On which specific channels is POOM observing the most network activity?

Read the on-screen results

POOM sorts the results from the highest observed packet activity to the lowest. Each row displays:

  • Channel number — the identifier for the scanned radio channel.
  • Packet count — the total number of supported frames captured on that channel during the current measurement.
  • Percentage — that channel's share of all packets counted in the current scan.
  • Graph bar — a quick visual comparison of relative activity.
Location / timeRadioTop channelPacketsShareNotes
Room A / morningWi-FiRecordRecordRecordNearby APs or traffic burst
Room A / morning802.15.4RecordRecordRecordPossible owned Zigbee/Thread activity
Field note: a strong IEEE 802.15.4 peak on channel 15 indicates active 802.15.4 traffic on that channel. It can help you choose a fixed channel for a deeper authorized capture, but the count alone does not prove whether the traffic is Zigbee, Thread, or another 802.15.4 protocol.

Device controls

  • UP / DOWN: move vertically through the detected-channel list.
  • LEFT / RIGHT: move five rows at a time through the sorted channel list.
  • A: reset all statistics to zero and begin a fresh measurement without leaving the tool.
  • B: stop the current scan and return to the radio-selection menu.

Interpret the result carefully

Use identical scan duration and placement when comparing results. A brief burst can dominate a short scan, while distance, walls, antenna orientation, packet loss, radio coexistence, and channel dwell time can all change the ranking.

On ESP32-C5, 2.4 GHz and 5 GHz support depends on the configured band mode. Automatic band mode does not mean simultaneous dual-band operation. The available 5 GHz channel set also depends on the regulatory domain, DFS policy, firmware configuration, and channel width, so do not assume a fixed number of non-overlapping channels.

Next step: use the highest relevant channel as a starting point for a fixed-channel, authorized PCAP capture later in this lab, then compare whether the longer capture confirms the same pattern.

Technical reference: Espressif's ESP32-C5 Wi-Fi Driver guide documents band modes, channel configuration, bandwidth, regulatory behavior, and DFS scanning.