One of the difficulties of locating a radio source, especially in environments with a lot of obstacles (i.e. A city or dense forest) is that even one may estimate the approximate direction with the use of directive antennas, there are several problems difficult to overcome:
- Distance is difficult to estimate as nor the radiated power neither the obstacles between the detector and the source (attenuating the signal) are known.
- Trilateration/Triangulation requires to setup a receiver infrastructure
- Changes in position of the source make difficult tracking the source or using static receivers.
Our proposal consists of mounting receivers in the form of ultra wide band software defined radio front ends over drones. The drone formation will consist of three drones (even this number is not a limitation and may be enlarged) equipped with the radio receiver and a Galileo GNSS receiver. The following figure depicts this architecture.
When deployed over an area, the drones will form a standard formation in the form of regular triangulum parallel to the ground, at a certain altitude. The drones will have radio receivers which shall be configured to monitor a specific frequency so that a first measurement of the received signal strength on each drone is made.
The drones will make use of multilateration techniques and processing of received signal to triangulate the position of the radio source, using this information and each drone position provided by Galileo receivers.
The implementation requires, as already said, Galileo GNSS receivers on each drone as well as radio front end and communications means (which may be standard RF-based or cellular based like 5G).
The system is thought to be a cheap, easy deployable system which allows a user to quickly locate the source within an area of interest. Its applications are in the domains of Search and Rescue, Law enforcement, Site and Border Surveillance and more.