---
title: "ESP-SDR turns an ESP32 into a raw IQ receiver"
description: "The ESPARGOS team found a way to capture raw IQ samples from the ESP32 Wi-Fi modem with no extra hardware."
date: 2026-10-01T12:00:00+02:00
lastmod: 2026-11-03T00:46:22+01:00
url: https://klimek.link/posts/2026-10-01-esp-sdr-raw-iq/
author: "Marcin Klimek"
source: https://klimek.link/posts/2026-10-01-esp-sdr-raw-iq/
---

# ESP-SDR turns an ESP32 into a raw IQ receiver

Source: [ESPARGOS, ESP-SDR: Raw IQ Capture with Espressif's ESP32 Chips](https://espargos.net/espsdr/)

The ESPARGOS team found that the ESP32 can capture raw radio samples. An undocumented debug path, probably left in for factory testing, skips the Wi-Fi modem and writes IQ samples straight into the chip's memory, which turns an ordinary dev board into a software-defined radio around 2.4 GHz. They found it by starting from one test function in Espressif's library and reverse engineering it with help from LLMs. There's a browser demo that works over Web Serial with most ESP32 boards.

**TL;DR**

- Undocumented ESP32 modem debug path, raw IQ into SRAM
- No extra hardware; probably left in for on-wafer testing
- Chips: ESP32, C3, C5, C6, C61, S2, S3, S31
- Tuning: 2.2-2.7 GHz; 4.8-6.0 GHz on C5 only
- Up to 80 MSa/s, ~13-54 MHz bandwidth, auto or manual gain
- Sample: 32-bit word, 10-bit I + 10-bit Q + gain index
- Bottleneck: 2,560 Mbit/s off-chip; browser demo works in bursts
- ESP32-S31: continuous 20 MSa/s (USB) or 40 MSa/s (Gigabit Ethernet)
- SoapyESPSDR driver for Gqrx and GNU Radio (experimental)
- ESPARGOS One: 8-channel phase-coherent SDR at 2.4 GHz

Source: https://klimek.link/posts/2026-10-01-esp-sdr-raw-iq/