Lidar News speaks with Chief Scientist and CEO David Hall about Hall Lidar’s recent announcement of its AI-based acoustic drone detection system, the UDL-64 (Ultimate Drone Listener).
Hall Lidar is a U.S.-based developer of advanced sensing and counter-UAS technologies. The UDL-64 system is designed to deliver real-time 3D situational awareness in complex operational environments through passive acoustic sensing.
The system is fully designed, engineered, and manufactured in the United States and is intended to provide an affordable approach to distributed drone detection across a wide range of deployment scenarios.
The Technology
The drone detection system operates independently of RF signals, GPS availability, or visual conditions. It emits no active signals during operation and functions passively through acoustic sensing.
Acoustic signatures serve as the system’s primary detection modality, allowing it to operate without reliance on external emissions such as RF links or satellite positioning. The platform is designed for environments where electronic signals may be limited, degraded, or unavailable.
Integrated connectivity options — including Wi-Fi, Bluetooth, and 5G — allow the system to interface with broader command-and-control architectures when required. In standalone mode, a single unit can detect drones at distances of up to approximately 200 meters. Multiple coordinated units can expand effective coverage to roughly 500 meters, depending on the environment and deployment geometry.
While acoustic drone detection systems have emerged globally in recent years, Hall Lidar’s UDL-64 is fully designed, engineered, and manufactured in the United States. According to CEO and Chief Scientist David Hall, the system was designed to balance performance, adaptability, and affordability across a range of deployment scenarios while supporting supply chain traceability and alignment with federal procurement requirements.
The full press release with more details on the system is available here.
Below, is an exclusive interview with insights from David Hall.
Conversation with David Hall, Head Scientist and CEO of Hall Lidar
How does the UDL work and what sets it apart from other detection systems?
The UDL uses advanced AI in conjunction with acoustical technology to support drone detection at a lower cost than traditional systems. A single UDL unit can be installed on top of a building to listen for incoming drones.
It can determine direction, approximate altitude, speed, and classification using onboard AI processing combined with acoustic sensing.
Why do you call it the UDL?
It stands for the Ultimate Drone Listener. “Ultimate,” implies best in class. The UDL is intended to be the best drone listening technology that anybody will ever be able to produce. It is ultimate because there are no compromises on the quality of the product.
We had a business selling audio, mostly subwoofers, back in the home theater days, and my first product was the ULD18. It stood for Ultra Low Distortion, and we sold it for quite a few years. I had the majority share of the powered subwoofer business called Velodyne Acoustics.
This new acoustical product is a play on that earlier product name. “Ultimate” represents best in class. The ULD18 was the best in class in its day.
How does a network of UDL’s work?
You can have miles of them placed every hundred feet around the perimeter of, say an airport. They would form a ring of listening units to detect incoming drones coming from any direction, miles away. It’s low enough cost that you can afford to build hundreds of these things and have them networking together.
If you wanted to protect a facility—small or large—you would ring it with a number of these units, spaced about 100 yards apart, or even closer depending on the perimeter.
If any one of them detects a drone, and ideally more than one does, the system can confirm the detection across multiple nodes. Once that happens, the network can focus attention on that specific area and gather additional information, while also alerting the rest of the system that a drone has been detected.
You could also deploy two concentric rings: an outer early-warning layer and an inner layer closer to the asset. If a drone moves inward, it is picked up again as it crosses into the second ring, providing continuous tracking.
A network working together in this way can support detection around airports, government compounds, utilities, or neighborhoods. Detection at one location can also be shared with another if a drone is moving across areas.
A key part of the system is classification—distinguishing legitimate aircraft from drones. A significant amount of software processing is involved in handling and interpreting that data.
We can identify a rogue drone by comparing it against known air traffic. The system can query national databases to determine whether a drone is properly registered, and it can also reference aircraft registries to confirm that manned aircraft are known types operating within expected parameters.
These classifications are continuously updated, and there is ongoing database interaction to improve accuracy and isolate targets in real time.
Over time, this can scale into a broader network where any individual sensor can trigger an alert across the system when a drone is detected. As more units are deployed, the system becomes more reliable and more effective, improving both coverage and confidence in detection.
You can also imagine smaller-scale deployments, where neighbors each install a unit and form a local detection network. A handful of devices working together could provide shared awareness of drone activity in a neighborhood.
The longer-term goal is a standardized network of drone listeners, with consistent data formats and communication protocols to support broader interoperability.
How far away can the UDL detect a drone?
Detection range varies depending on the location and the type of drone. Smaller drones can typically be detected at a range of a few hundred meters, while larger systems can be detected at distances of up to five miles or more.
Range is highly dependent on environmental noise and the acoustic signature of the drone. In general, performance varies with conditions.
Larger gasoline-powered drones, such as those used in Ukraine, are often easier to detect because they produce noise comparable to a small aircraft and can be heard at distances of up to several miles.
How is the network connected to a response center?
A user terminal communicates data through the cloud via Ethernet or wireless connections such as Wi-Fi. The interface typically includes a screen and map display, and can be designed to integrate with a broader national network of drone detection systems.
In some deployments, direct satellite communication may also be used.
The system includes a discovery protocol that allows units to identify and connect with other nearby networks. Each unit is assigned a GPS location, enabling it to establish where it is and automatically form a network with neighboring devices.
In this way, units can connect peer-to-peer, linking with nearby sensors to form a coordinated system. Depending on the deployment environment, there are multiple connectivity options and configurations.
How discreet are the units? Are they going to look like the cameras that are now on traffic lights and poles?
The first model is slightly larger because it is designed for maximum sensitivity. However, future versions could be made much smaller—potentially around the size of a Frisbee.
In that form factor, the units could be quite inconspicuous and visually simple, allowing them to blend into their surroundings. They could be mounted on telephone poles, rooftops, and other existing infrastructure without drawing attention.
There is significant flexibility in how and where the systems can be deployed.
What is the next step once a drone is detected?
This is a separate project. Hall Lidar is actively working on a non-lethal method of capturing the drone with a net. This is a separate initiative. Stay tuned.
For pricing, delivery, and more information visit https://halllidar.com/.
About Hall Lidar Inc.
Hall Lidar Inc. is a U.S.-based developer of advanced sensing and counter-UAS technologies focused on protecting critical infrastructure, national security assets, and public environments. By combining innovative engineering with multi-sensor intelligence, the company is redefining how aerial threats are detected and mitigated. Founder and serial inventor David Hall holds more than 100 patents and received the 2018 Inventor of the Year award from the Smithsonian Foundation. He is known for industry-foundational work in LIDAR, acoustics, marine stabilization, electric-magnetic propulsion and AI-enabled detection and neutralization systems.
