TL;DR
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Several projects have reported undocumented ways to capture raw IQ samples from ESP32 microcontrollers, turning some models into limited software-defined radio receivers. Most setups can export only snapshots, while one ESP32-S3 prototype uses an FPGA for continuous PC streaming; its clocking currently causes poor phase noise.
Several independent hardware projects have reported that some ESP32 microcontrollers can capture raw in-phase and quadrature (IQ) radio samples, an undocumented capability that could let the chips act as limited software-defined radios. The finding supports spectrum analysis across parts of the 2.2–6.0 GHz range, depending on the model, but most boards cannot stream enough data to a computer for continuous decoding.
The ESPARGOS team said its work uncovered a way for firmware on several ESP32 models to bypass their usual Wi-Fi and Bluetooth functions and obtain raw baseband samples. Reported coverage varies by chip: the source gives 2.2–2.7 GHz for several models and an additional 4.8–6.0 GHz range for the ESP32-C5. Sampling rates can reach 80 million samples per second, with analog bandwidth estimated at roughly 13–54 MHz depending on the device.
Those figures do not mean that every ESP32 board can operate as a conventional, continuously streaming PC radio. The report says that most models have insufficient output bandwidth for that use and can export only short data snapshots. That supports spectrum displays and waterfall visualizations, but not continuous demodulation or decoding on a connected computer using the chip alone. ESP-WebSDR provides browser-based firmware flashing and a live spectrum and waterfall view for many development boards, according to the report.
A separate ESP32-S3 project by Reddit user /u/h0m3us3r, uploaded to GitHub on September 26, uses an FPGA as a USB 3 front end to send IQ data continuously to a PC. That may allow computer-based signal processing, but the reported prototype has poor phase noise because the FPGA clocks the ESP32. The report also describes C5VRX, a project posted on GitHub on August 13 that uses an ESP32-C5 to receive 5.8 GHz FPV video and demodulate it onboard. It outputs analog composite video through a resistor-based digital-to-analog converter and remains unreliable at range.
What ESP32 SDRs Can Do
The discovery could give developers a low-cost way to experiment with radio-frequency measurement and signal processing using hardware they may already own. In ESPARGOS, access to phase-coherent IQ capture means the team says its antenna array can attempt direction finding on arbitrary signals in the 2.4 GHz band, rather than being limited to Wi-Fi and Bluetooth signals. That extends the project’s original use beyond locating familiar wireless transmissions.
For general radio users, the limitation is just as important as the capability: sample capture is not the same as a complete SDR. Snapshot-only output restricts what can be analyzed, while continuous processing depends on additional hardware or a different chip. The S3-and-FPGA experiment points to a possible route to wider use, but its phase-noise problem remains a practical obstacle, and the C5 video receiver is still a work in progress.
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From Wi-Fi Array to Radio Capture
ESPARGOS was previously reported in 2025 as a phased array built from multiple patch antennas, each connected to an ESP32 Wi-Fi microcontroller. Its stated purpose was to estimate the direction from which Wi-Fi signals arrive and render that information as a live augmented-reality heatmap. The newly reported IQ capture changes the range of signals that the hardware may be able to examine.
The October 1 report says the discovery was not confined to one team: at least two other projects appear to have found the same or a similar capability independently, while pursuing different applications. The ESP32-S3 project adds an FPGA to handle continuous data transfer, while C5VRX focuses on receiving and displaying FPV video. The projects are evidence of separate implementations, but the available report does not establish that all three use an identical technical mechanism.
“Phase-coherent IQ sample capture is now possible with their hardware.”
— ESPARGOS team, as described in the RTL-SDR.com report
software defined radio receiver ESP32
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Limits and Open Technical Questions
The report does not provide a model-by-model test table or independent measurements for the stated frequency ranges, sample rates and analog bandwidths. Those specifications are therefore best treated as reported project capabilities, not as verified performance across all ESP32 boards. Exact results may depend on the chip, board design, firmware and test setup.
It also remains unclear when the S3-FPGA prototype’s clocking issue might be resolved, and whether it can deliver stable performance suitable for continuous demodulation. The C5VRX project is described as unreliable at range, with no performance figures supplied. A SoapySDR driver for the ESP32-S31 is reported as forthcoming, but the report gives no release date or independent evaluation of its operation.
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Drivers and Prototype Testing
The next indicators will be whether ESPARGOS releases more implementation details and whether the promised SoapySDR support for the ESP32-S31 becomes available for GNU Radio and gqrx. The report says the S31 can stream continuously at up to 16 million samples per second over Gigabit Ethernet, a feature that could distinguish it from snapshot-based setups.
Further testing will also show whether the ESP32-S3 and FPGA combination can improve its clocking and phase noise, and whether C5VRX becomes reliable enough for practical FPV reception. Until those developments are demonstrated, the projects show promising but varied experiments—not a uniform, plug-and-play replacement for established SDR hardware.
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Key Questions
Can any ESP32 board be used as a general-purpose SDR?
No. The reported capability applies to several ESP32 models, and performance varies. Most setups are limited to exporting snapshots rather than continuously streaming data to a PC.
What frequencies can the reported projects receive?
The RTL-SDR.com report gives a range of 2.2–2.7 GHz for several chips and says the ESP32-C5 also covers 4.8–6.0 GHz. These are project-reported capabilities, not a guarantee for every board.
Can an ESP32 decode signals on a computer?
Most described boards cannot provide the required continuous data stream on their own. An ESP32-S3 project uses an FPGA to stream samples to a PC, but its prototype has a reported phase-noise problem.
What is ESPARGOS using the discovery for?
ESPARGOS says phase-coherent IQ capture lets its antenna array perform direction finding on arbitrary signals in the 2.4 GHz band, rather than only Wi-Fi and Bluetooth signals.
Source: hn
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