GoKawiilESPARGOS team finds undocumented SDR mode in several ESP32 chips
The ESPARGOS project, known for a WiFi direction-finding antenna array built on ESP32 microcontrollers, discovered an undocumented feature letting firmware bypass fixed WiFi/Bluetooth hardware to capture raw IQ baseband samples. This turns several ESP32 models into software-defined radios covering 2.2–2.7 GHz (plus 4.8–6.0 GHz on the ESP32-C5), with sample rates up to 80 MS/s. The newer ESP32-S31 can stream continuously at 16 MS/s over Gigabit Ethernet, and a browser-based tool called ESP-WebSDR lets users flash the firmware and view a live spectrum waterfall.
GoKawiil's interpretation of the reporting above, not reported fact.
Because output bandwidth is limited, most ESP32 chips can only snapshot spectrum data rather than continuously demodulate signals, so the practical use case is closer to a spectrum analyzer than a full SDR receiver. The discovery expands ESPARGOS's direction-finding capability beyond WiFi and Bluetooth to any signal in the 2.4 GHz band, and the team says phase-coherent transmission is technically possible but is being withheld over misuse concerns. That multiple independent researchers stumbled on the same hidden feature around the same time suggests it may become a widely adopted low-cost SDR technique for hobbyists.
- Several ESP32 chips contain an undocumented mode for raw IQ baseband sample capture
- ESPARGOS can now direction-find arbitrary 2.4 GHz signals, not just WiFi/Bluetooth
- Only the ESP32-S31 supports continuous streaming (16 MS/s via Ethernet); others offer snapshot-only spectrum analysis
ESP32-DevKitC Development Board — If you want to try out this hidden SDR trick yourself, a basic ESP32 dev board is the cheapest way to start experimenting with raw IQ baseband capture. It's a great way to explore the spectrum analyzer capabilities described in the article without needing dedicated SDR hardware. Perfect for hobbyists who want to tinker with WiFi/Bluetooth chip internals and radio signal capture.”,
See ESP32-DevKitC Development Board on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.Source: rtl-sdr.com — Written By, 2026-10-01
Published there as: “Various Projects Find Hidden SDR Capabilities in ESP32 Microcontrollers”
Read the original report → The summary and analysis above are GoKawiil's own, written from reporting by the source above. Facts and quotes belong to the original publisher.