A developer known as [marble] has released early ESP32 firmware that lets the chip's 2.4 GHz radio transmit as well as receive, extending last week's listen-only software defined radio hacks.
Last week, two seemingly simultaneous projects showed how to get raw access to radio samples from the 2.4 GHz radio found in many ESP32 variants. That turned the chips into receive-only software defined radio (SDR) platforms, which covers only half of what an SDR can do.
Over the weekend, [marble] set out to change that. The developer released an early version of ESP32 firmware that can also transmit, and got it working with the gqrx software. In a demonstration, an ESP32-S3 and an ESP32-C6 communicated with each other using a Hellschreiber mode, something well outside the WiFi specification.
[marble] is not stopping there. Work is under way on 802.15.4 modulation, which could eventually let an ESP32 speak ZigBee.
The project operates in roughly the 2.4 GHz band, though [marble] suggests it may work down to 1.8 GHz. Hackaday corrected an earlier figure of 100 MHz that it had published in error. That leaves some territory still to be explored, and the limits of the ESP-SDR appear to be only beginning to be tested.
The original coverage compared the moment to the early RTL-SDR hacks, which set off a wave of hobbyist experimentation with SDR. Credit goes to [marble] and to the Espargos team, whose original hacks started the effort.
Source: Hackaday
