Ukraine’s FENEK acoustic system now detects cruise missiles

A Ukrainian company has expanded its FENEK acoustic detection system to identify Shahed-type drones at ranges up to three kilometers and cruise missiles at up to five kilometers, according to Militarniy.

The FENEK system, developed by a Ukrainian manufacturer, operates on a principle that has become increasingly relevant as the war has driven both sides to develop countermeasures against each other’s electronic detection capabilities: it only listens. The system emits nothing — no radar signal, no radio frequency emissions, no electronic output that electronic warfare systems can detect, locate, or suppress. For a military environment saturated with jamming and signals intelligence, that invisibility is not a secondary feature. It is the system’s core operational advantage.

The architecture behind FENEK is a network of acoustic sensors, each equipped with an array of multiple microphones and an onboard computing module that analyzes incoming sound, filters ambient noise, and determines the direction of a detected signal. The method the system uses — Time Difference of Arrival, known as TDOA — measures the minute delays between the same sound reaching different microphones in the array. Because sound travels at a known speed and each microphone sits at a known position relative to the others, those time differences allow the computing module to calculate the angle from which the sound originated. A single sensor can determine direction but not precise location. That limitation is where the network architecture becomes critical.

When multiple FENEK sensors in a distributed network simultaneously detect the same acoustic source, each providing its own directional data, the system triangulates across those overlapping measurements to calculate the target’s coordinates. The result is not simply “a drone is somewhere in that direction” — it is a position fix, updated in real time as the target moves, displayed on an operator workstation as coordinates, a movement track, heading, and speed. The workstation requires no internet connection to function, which matters for forward-deployed units operating in areas where connectivity is degraded or denied. Operators can also listen to live audio feeds from individual sensors for additional manual verification of what the system has detected.

The specific capabilities the manufacturer highlighted to the Ukrainian outlet Militarny place FENEK in operationally meaningful detection windows. Three kilometers of warning against a Shahed-type drone gives a ground crew or air defense system enough time to engage or take protective measures before the weapon reaches its target — particularly in combination with a broader air defense network that can be cued by the acoustic detection. Five kilometers against cruise missiles is a shorter window given the speed differential, but in a dense sensor network with overlapping coverage, it provides valuable early warning that complements radar-based detection systems.

The capability against fiber-optic controlled drones is the detail that most directly addresses the current state of the war. Fiber-optic drones — unmanned systems that receive control signals through a thin optical cable rather than a radio link — produce no radio frequency emissions at all. They are invisible to electronic intelligence systems that monitor the radio spectrum and immune to the radio frequency jamming that has been the primary electronic countermeasure against conventional drones. A drone that cannot be detected by its radio emissions and cannot be jammed because it has no radio receiver presents a detection challenge that purely electronic counter-drone systems cannot solve. FENEK’s acoustic approach bypasses the entire radio frequency dimension of the problem entirely: regardless of whether a drone uses radio control, satellite uplink, autonomous programming, or fiber-optic cable, it still produces sound from its motors and propellers — sound that FENEK is designed to detect.

This distinction has become operationally significant in Ukraine, where Russian forces have increasingly deployed fiber-optic FPV drones specifically to defeat Ukrainian electronic warfare and radio frequency detection systems. A passive acoustic system that detects the physical presence of the drone through its sound signature, rather than its electronic emissions, represents a category of solution that the fiber-optic countermeasure cannot defeat.

The urban security application the system also supports — detecting explosions, loud incidents, and monitoring security conditions in populated environments — points to a dual-use potential that acoustic detection systems have demonstrated in civilian security deployments worldwide. In the Ukrainian context, that capability means the same sensors protecting a military position can also support civilian emergency response monitoring in the surrounding area.

Acoustic drone detection is not a new concept — it has been explored and deployed by various military and security organizations for several years. What FENEK represents is the application of that concept by a Ukrainian developer in direct response to the specific threat environment of the current war, refined by operational feedback from a conflict that has driven faster tactical and technical adaptation than any peacetime development program could achieve. The decision to prioritize detection of Shahed-type drones, cruise missiles, and fiber-optic controlled systems — exactly the threats Ukrainian forces face every day — reflects a development process shaped by real operational requirements rather than projected threat assessments.

When the first signal of an incoming threat is a sound rather than a radar return or a radio emission, the systems that hear that sound first determine who has time to respond. FENEK is built around that reality.