Level 1 · Nothing has to fly

Stachelschwein Scanner

The sky already talks. Most of it talks in a standard you can hear with a 12 EUR board.

01 · What the scanner is

A node that reports a bearing, never a finished position.

That is the protocol rule, and it is also the hardware rule. One roof hears. Several roofs make a track. If your first box tries to be a radar, a camera and a fighter, you will still be soldering in November.

Weekend one: hear Remote ID. Weekend two: hear propellers. Weekend three: speak DETECTION.

02 · Four ears, in this order

A · RID
Bluetooth and Wi-Fi broadcast of operator ID, serial, position, altitude, speed. OpenDroneID. Required in the EU since 1 January 2024 for C1 to C3 in Open and for every drone in Specific. Phone app for zero EUR, ESP32-S3 for about 12 EUR. Hears legal EU drones that actually transmit. Does not hear a Mini in C0, a fibre-optic FPV, a military bird, a dark inbound.
B · Sound
Four ICS-43434 MEMS mics in a small plus, as in VolAnti: a 91 mm box, ESP32-S3, the harmonic comb of a multirotor. This is the ear for aircraft that emit no radio. At that size the array is a sensitivity device, not a direction finder. Bearing comes from several boxes, or from a larger array later.
C · Radio
An RTL-SDR does not hear 2.4 GHz. The R820T2 dies near 1.8 GHz. If you want OcuSync, Lightbridge, analog 5.8 GHz video, you need a HackRF, a Lime, a Blade, or a German professional box from Aaronia. DJI DroneID on OcuSync is a separate family from EU Remote ID. Ruhr-Universität Bochum published a receiver in NDSS 2023.
D · Confirm
A Pi Camera Module 3 looking up. Birds, airliners, insects. Never the first detector. Always the witness.

03 · The German radar question

Infineon is 15 metres. HENSOLDT is a vehicle.

The XENSIV BGT60TR13C is a Munich 60 GHz chip with antennas in the package. Datasheet max range: 15 m. Presence in a room, a drone over the garden table. It is not a city shield. The SPEXER 2000 3D MkIII is the German C-UAS radar: X-band AESA, micro-Doppler, already in Bundeswehr programmes (Boxer C-UAS with Kongsberg, ASUL, HoWiSM, NNbS). Antenna mass about 36 kg. That is layer two: fire brigade, THW, the army. The roof gets ears first.

04 · Weekend bill of materials

Already own a phone
OpenDroneID receiver or Drone Scanner. Walk outside. That is the test of the idea, not of the box.
RID box
ESP32-S3-DevKitC · USB-C cable · weather case · firmware RID_Scanner or OpenDroneID ESP32 example · ~25 EUR
Acoustic box
4 × ICS-43434 · ESP32-S3 · 91 mm printed shell · VolAnti firmware · ~50 EUR
Node brain
Raspberry Pi 5 8 GB · official PSU · case · speaks DETECTION on the LAN · ~110 EUR

The Pi is assembled in Wales, designed in Cambridge. The ESP32 is Espressif in Shanghai. That tension is documented on the supply page. We still start with the ESP32 because it hears RID this weekend. A European MCU path is a ranked item, not a reason to wait.

Fakten-Tabelle · Fact table
Fakt
C0 drones under 250 g (many DJI Mini) often have no Direct Remote ID duty in Open. A RID scanner then sees sky.EASA Open category table from 1 January 2024
Fakt
VolAnti: four ICS-43434, 79 mm corner to corner, ESP32-S3, hears the rotor comb. Breadboard about 40 GBP.github.com/agamrossen/VolAnti
Fakt
Aaronia AARTOS (Strickscheid) is the German professional RF system. Vendor figures: consumer UAV to 40 km, MIL UAV to 80 km. 700+ installs, including Heathrow.aaronia.com · AARTOS product sheet
Hypothese
A roof with RID plus acoustic covers legal traffic and some dark FPV. Confidence: medium. False alarms (blackbird, leaf blower) are the unsolved operations problem.Systementwurf, open point