DIY Passive Drone RF Detector

Concept

This setup uses a Software Defined Radio (SDR) to passively monitor RF spectrum ranges commonly used by consumer drones. You are not decoding encrypted traffic or transmitting anything — only observing signal activity.

Goal: detect presence of drone control / telemetry links by watching spectrum spikes and patterns.

Parts List

Option A — Airspy

• Airspy R2 or Airspy Mini
• Wideband antenna (25–6000 MHz preferred)
• USB extension cable
• Optional LNA (NooElec LNA or similar)

Option B — SDRplay

• SDRplay RSP1A / RSPdx
• Wideband antenna
• USB cable
• Optional external LNA

Common

• Laptop (Windows / Linux / macOS)
• Headphones (optional)
• Tripod or magnetic antenna mount

Software Stack

• SDR++ (recommended)
• SDR Console (Windows alternative)
• GQRX (Linux/macOS)
• Optional: Inspectrum (signal inspection)

Install your SDR drivers first, then install SDR++.

Common Drone Frequency Ranges

• 2.400 – 2.483 GHz (main control band)
• 5.725 – 5.850 GHz (video + control)
• 900 MHz ISM (some long‑range drones)
• 1.2–1.3 GHz (FPV analog, region dependent)

Most DJI / Autel / consumer drones live in 2.4 GHz and 5.8 GHz.

Step‑by‑Step Setup

1. Hardware

1. Connect antenna to SDR.
2. Plug SDR into laptop.
3. Place antenna outdoors or near window.

2. Software

1. Install SDR drivers.
2. Launch SDR++.
3. Select your SDR device.
4. Set sample rate ~10 MSPS.

3. Initial Calibration

1. Enable waterfall.
2. Adjust gain until background noise is visible but not saturated.
3. Verify FM broadcast appears around 100 MHz.

4. Scan for Drones

1. Tune to 2.45 GHz.
2. Watch for hopping carriers or wide digital blocks.
3. Repeat at 5.8 GHz.
4. Mark sudden strong signals that appear/disappear.

5. Pattern Recognition

• Drone links hop rapidly.
• Video downlinks appear as wide blocks.
• Signals move when drone moves.

Optional Automation

• SDR++ frequency bookmarks
• External scripts via TCP control
• RTL_433 style scanning (if using compatible SDR)

Advanced users can build alert scripts based on RSSI spikes.

Important Notes

• This is detection only.
• No transmission.
• No jamming.
• No decryption.

Always follow local RF and privacy laws.

Expected Results

• You detect activity, not identity.
• You see RF presence, not operator location.
• Range depends on antenna and environment.