ESPsoup, the open-source pocket spectrum scanner, has released Beta 0.4 — and it is no longer limited to its own little board. The new version, app 0.12.15 with firmware 0.7.1, can now use external software-defined radios, adds a 60 GHz radar tool, and picks up a set of mapping, recording and lookup features that make it a much more serious instrument. The software is GPL-3.0 licensed and based on ESP-SDR. It still runs on an ESP32-C5 board that costs about 15 to 25 euros, and it still never transmits: it is a receive-only scanner, listening to the radio spectrum between 2.13 and 2.73 GHz and between 4.79 and 5.99 GHz.
External SDRs over WebUSB
The headline change is support for external SDRs. ESPsoup can now connect to an RTL-SDR or a PlutoSDR through WebUSB in desktop Chrome or Edge, showing a live spectrum and waterfall in the browser. That matters because the board’s own receiver covers two bands; an external radio opens up whatever its hardware can hear. The RTL-SDR is the cheapest way into the hobby, and the PlutoSDR covers a much wider range — and both now work with the same interface, the same waterfall display and the same tools. The connection needs no driver install: the browser talks to the radio directly, which is what makes the setup practical on any desktop. For anyone who already owns an SDR, ESPsoup becomes a free front end; for anyone who does not, the board alone is still a complete scanner.
The 60 GHz radar tool
The second new feature is a 60 GHz radar tool. It reports presence, distance and a position trail, and it can even measure breathing and heart rate at ranges from 0.4 to 1.5 metres. It needs the Seeed MR60BHA2 kit, a small millimetre-wave radar module that plugs into the system. The use cases are practical rather than exotic: knowing whether a room is occupied, where someone is standing, or whether a person is breathing — all without a camera, and all from a device the size of a pocket radio. It is a reminder of how far millimetre-wave sensing has come down in price, and how much sensing a tiny board can now do.
Mapping, recording and lookup
Beta 0.4 also fills in the workflow around the scanning itself. Offline OpenStreetMap tiles mean the map works without an internet connection — useful in the field, where coverage is the first thing to go. Diagnostics can now be recorded, including raw I/Q samples in SigMF format, so a signal seen once can be replayed and studied later instead of being lost the moment it stops. Mobile-network blocks are listed per EU country, vendor MAC addresses can be looked up on the spot, and the Find tool has been improved: gain now drops in 10 dB steps, bearings can be taken from body shadow, and the position estimate is terrain-aware. Each of these is a small thing on its own; together they turn a pocket toy into a field instrument.
What it can hear
What the scanner listens to is broad. It decodes Bluetooth LE, Zigbee, Thread, nRF24 and Wi-Fi beacons, reads LTE and 5G cell IDs, and picks up drone Remote ID broadcasts — the signals drones use to announce themselves, which are becoming a first step in drone detection for anyone watching the air. The TV tool shows analogue FPV video across 52 channels at 24 to 28 frames per second, which is how first-person-view drone feeds appear on a spectrum scanner. And through it all, the device never transmits anything of its own: it listens, decodes and displays, which keeps it legal to use in most places and safe to carry anywhere.
Why it matters
ESPsoup matters because it puts real radio-frequency awareness in a pocket for the price of a dinner. For counter-drone work, that means more people can see the spectrum drones use — the control links, the video feeds, the Remote ID beacons — without buying laboratory equipment. The project is also a useful reminder that the radio spectrum is shared: the same bands that carry Wi-Fi and Bluetooth also carry drone links, and anything that can see one can learn to see the other. Cheap, open tools do not replace professional drone detection systems, but they change who can look, and how often. Expect the gap between hobbyist scanners and professional gear to keep shrinking, and expect the ideas from tools like this one to show up in professional equipment next.
Source: ESPsoup