Problem

Modern unmanned aerial vehicle (UAV) operations depend heavily on Global Navigation Satellite Systems (GNSS) and radio-frequency (RF) communications for positioning, timing, synchronization, and command dissemination. In military operations, underground facilities, tunnels, industrial plants, warehouses, and disaster-response environments, these signals may be unavailable, intentionally jammed, or restricted, creating a critical vulnerability for autonomous and cooperative UAV missions.

Solution

LunaSonar introduces a GPS-inspired acoustic Positioning, Navigation, Timing, and Command (PNTC) network operating in the ultrasonic frequency range of approximately 20–50 kHz. The system uses synchronized acoustic pseudolites to create a local navigation infrastructure capable of supporting large UAV swarms in RF-denied environments.

Unlike conventional ultrasonic localization systems that focus solely on positioning, LunaSonar provides a combined Positioning, Navigation, Timing, and Command capability through a unified spread-spectrum waveform. The same infrastructure simultaneously delivers navigation references, precision timing, synchronization, and command information required for coordinated autonomous operations.

Innovation

The proposed waveform employs separate quadrature signal components with distinct functional roles. The in-phase (I) channel carries navigation and command data, while the quadrature (Q) channel continuously transmits a dedicated pilot signal used for acquisition, tracking, synchronization, and ranging.

The pilot signal utilizes a tiered spreading-code architecture consisting of primary, secondary, and tertiary codes that combine to form extremely long effective spreading sequences with excellent correlation characteristics. This architecture enables rapid receiver acquisition, robust tracking, high-precision timing measurements, and operation below ambient acoustic noise levels generated by UAV propellers, machinery, and environmental sources.

Each acoustic pseudolite is assigned a unique spreading code, allowing multiple transmitters to operate simultaneously within the same environment. Large families of low-cross-correlation codes enable support for numerous pseudolites and UAV users while minimizing mutual interference. This code-division architecture allows the network to scale from a small indoor deployment to large cooperative swarm operations.

Advantages

The long effective spreading sequences provide substantial processing gain, allowing reliable reception of very weak acoustic signals while suppressing noise, reflections, and interference. The dedicated pilot channel supports accurate time-of-arrival measurements for positioning and synchronization, while the data channel distributes mission updates, swarm-control commands, geofencing information, and system status messages.

LunaSonar creates a local GPS-like navigation infrastructure using spread-spectrum ultrasonic pseudolites, enabling positioning, timing, synchronization, and command distribution for autonomous UAV swarms in RF-denied environments.

Applications

Potential applications include defense operations in GNSS-contested environments, autonomous warehouse logistics, underground and tunnel navigation, industrial inspection, emergency response, mining operations, and coordinated multi-UAV missions. By combining spread-spectrum communications, precision timing, navigation, and command distribution into a unified acoustic waveform, LunaSonar establishes a new class of resilient navigation infrastructure for autonomous systems operating beyond the reach of conventional RF-based technologies.