BVLOS (Beyond Visual Line of Sight) drone operations require accurate and reliable navigation systems to ensure that the drone remains within a defined airspace and avoids obstacles. There are several navigation systems used in BVLOS drone operations, including GPS and visual markers.

1. GPS (Global Positioning System): GPS is a satellite-based navigation system that provides accurate location and time information. BVLOS drones use GPS to determine their location, altitude, and speed. The GPS receiver on the drone communicates with a network of satellites to determine its position, and the information is then sent to the drone's autopilot system, which controls the drone's movement.
2. Visual Markers: Visual markers are physical markers on the ground or in the air that provide a reference point for the drone's navigation. These markers can include painted lines on the ground, reflective markers, or other visual cues that help the drone maintain a defined path. Visual markers are especially useful when GPS signals are weak or disrupted, or in areas where GPS signals are unavailable, such as in urban canyons.
3. LiDAR (Light Detection and Ranging): LiDAR is a technology that uses lasers to measure distances and create 3D maps of the environment. BVLOS drones can use LiDAR to create a detailed map of the area in which they will be operating. This map can then be used to guide the drone's movements and avoid obstacles.
4. INS (Inertial Navigation System): INS is a navigation system that uses accelerometers and gyroscopes to determine the drone's position, velocity, and attitude. INS is useful in areas where GPS signals are weak or disrupted, as it provides a more accurate measure of the drone's movement.

Overall, BVLOS drone operations require a combination of navigation systems to ensure safe and accurate flight. GPS is the primary navigation system used in BVLOS drone operations, but visual markers, LiDAR, and INS can be used to supplement GPS and provide additional information to the drone's autopilot system.