Radio-frequency (RF) detection is the only technology that identifies the drone and locates its pilot, passively and without line of sight, but it cannot see a drone that flies without any radio link. Radar sees silent drones but does not identify them. Cameras confirm visually but need line of sight. Acoustic sensors work at short range. A robust site combines RF with at least one of the others.
Three questions, not one
“Detecting a drone” hides three distinct questions. Is there a drone? (detection). Which drone is it, and is it authorised? (identification). Where is the person flying it? (location of the pilot). A sensor that only answers the first question raises an alarm; a sensor that answers all three lets a team act.
The table below summarises what each family of sensors brings. The sections that follow explain the trade-offs.
| Technology | Detects | Identifies the drone | Locates the pilot | Line of sight | Emits |
|---|---|---|---|---|---|
| RF detection | Drones with a radio link | Yes (decoded protocols, Remote ID) | Yes (DJI, Remote ID) | Not needed | No |
| Radar | Any flying object | No | No | Needed | Yes |
| Cameras | Objects in view | Visual class only | No | Needed | No |
| Acoustic | Rotor noise, short range | Class only | No | Not strictly | No |
| Remote ID receiver | Compliant drones only | Yes (broadcast ID) | Yes (broadcast) | Not needed | No |
Radio-frequency (RF) detection
Almost every drone in service talks to its remote control by radio: commands go up, video and telemetry come down. RF detection listens to that link. Matching what it hears against a library of signatures, it recognises the protocol, and for some manufacturers (DJI in particular) it decodes the identity: model, serial number, drone position, pilot position and take-off point. It also receives the Remote ID broadcast required in Europe since 1 January 2024.
- Strengths: passive (emits nothing, needs no licence, cannot be detected by the drone), works without line of sight in dense urban terrain, identifies the drone, and is the only family of sensors that reveals where the operator stands.
- Limits: a drone flying a pre-programmed route with its radio link switched off emits nothing to hear; unknown or custom protocols are detected as energy in a band rather than identified; analog FPV drones carry no identity at all, only a video carrier.
Radar
A radar emits and listens for echoes, so it sees any object in the air, including a drone with its radio silent. Modern counter-drone radars track many targets at once over several kilometres.
- Strengths: detects non-emitting drones, gives precise range and speed, works day and night.
- Limits: it does not tell you which drone it is or who is flying it; birds and clutter cause false alarms that must be filtered; it needs line of sight and suffers in dense urban areas; it is an emitter, subject to frequency authorisation.
Cameras (visible and thermal)
Cameras, often PTZ cameras steered by another sensor, give the visual confirmation that operators and investigators expect, and modern video analytics can classify a drone in the image.
- Strengths: visual proof, classification (drone, bird, aircraft), payload observation, and many sites already own the cameras.
- Limits: line of sight only; a small drone occupies a few pixels beyond a few hundred metres; fog, rain, glare and night reduce performance (thermal helps at night); no pilot location.
Acoustic sensors
Microphone arrays recognise the sound signature of rotors.
- Strengths: passive and inexpensive, can hear a drone that emits no radio.
- Limits: short range, typically a few hundred metres, and degraded in noisy environments such as stadiums, cities and industrial sites.
Remote ID receivers
A Remote ID receiver reads the identity a compliant drone broadcasts over Wi-Fi or Bluetooth: identifier, position, altitude, and the position of the pilot or take-off point.
- Strengths: rich, standardised data, cheap receivers.
- Limits: cooperative only. A non-compliant drone, a drone under 250 g or a drone with Remote ID disabled shows nothing. It is a layer, not a system.
How to choose for a site
Start from the threat and the terrain, not from the sensor:
- Events and temporary sites (concerts, sport, official visits): a portable, passive RF system set up in minutes covers the large majority of consumer drones and points teams to the pilot. Handheld FPV detectors protect agents close to the public.
- Permanent sensitive sites (prisons, energy, industry, airports): a fixed RF station on a mast, fused with radar where the threat includes radio-silent drones, and with cameras for visual confirmation.
- Sites that already own cameras: video analytics turn the existing camera network into an additional detection layer.
Whatever the mix, ask for a trial on your own site: range and detection performance depend on terrain, buildings and the radio environment, and figures measured elsewhere do not transfer.
Where SkyKraken fits
SkyKraken is a French company specialised in passive RF detection. SkyKraken Mobile is a portable case for temporary sites; SkyKraken Horizon is a fixed station that feeds C2, VMS, PTZ cameras and radar through an open API; SkyKraken SK-1 is a handheld detector for analog FPV drones on 1.2, 3.3, 5.8 and 6.5 GHz; and SkyKraken Eyes, in development as a pilot programme, adds drone detection to existing cameras in Genetec Security Center and Milestone XProtect. Every detection can be exported as a sealed evidence dossier.
Frequently asked questions
What is the best technology to detect drones?
No single sensor covers everything. Radio-frequency detection is the only technology that identifies the drone and locates its pilot, passively and without line of sight; radar detects drones that emit no radio but does not identify them; cameras give visual confirmation within line of sight. Sensitive sites usually combine RF with radar or cameras.
Can RF detection find the drone pilot?
Yes, for drones whose protocol carries the pilot position, such as DJI drones, and for drones broadcasting European Remote ID, which includes the pilot or take-off position. Analog FPV drones carry no identity, so an RF detector can only warn of their presence and show their video.
Can a drone avoid RF detection?
A drone flying a pre-programmed route with its radio link switched off emits nothing for an RF sensor to hear. Covering that threat requires radar, cameras or acoustic sensors in addition to RF.
Does passive RF detection need a frequency licence?
No. A passive RF detector only receives and emits nothing, so unlike a radar it needs no frequency authorisation. Jamming or taking control of a drone is a different matter: in France it is reserved to authorised state services.