In this case study we demonstrate the integration of a radiological SPIR-Explorer sensor from the company MIRION Technologies and an M 600 Pro from DJI. For radiological sensing applications, the distance between the potentially contaminated area and the control station is typically several kilometers due to safety reasons. In addition, in case of large scale disasters reliable communication infrastructure such as cellular networks cannot be assumed. The sensing system therefore has to provide its own data links.

For this case study two sensing scenarios were investigated:

1. Communication and sensing test of 60 hectares mission area
2. Radiation detection and classification with probe source of Cs-137

In order to support the mapping and analysis process on the ground, the acquired measurements are to be preprocessed and georeferenced in the air.
The application requirements are:

• Onboard preprocessing of sensor data
• Real-time transmission of sensor data
• Communication range larger than 1 km without cellular networks
• Onboard data buffering in case of connection loss and retransmission on reconnect
• Integration of received data into end-user application

Out of the box, no available system on the market meets the above requirements.
The SKIDER Communication and Control System is perfectly suited to address the foreseen application.

The SKIDER Mobile module connects directly to the UAV. In case of the DJI M 600 Pro, SKIDER Mobile is directly powered from the drone. The data connector implements the DJI Onboard SDK which allows full control of the drone to enable application sensitive mission and flight control.

SKIDER Air also directly controls and powers the radiation senor. The received data is enhanced with geo data in real-time and packaged for radio transmission. In this specific use case, SKIDER Link utilizes two redundant communication links operating at 2.4 GHz and 868 MHz. SKIDER Link
continuously evaluates the link performance and decides which data packet should be send over which link. In case of a connection loss, the sensor data is buffered and transmitted upon reconnection. The transmitted data is received by SKIDER Ground and integrated into the MIRION’s SPIR-Mobile analysis software.

In addition, the flight is monitored by the SKIDER-UI.

In this unique setup, it is possible that pilot and data analyst work side-by-side to achieve maximum efficiency.

The implementation was done in cooperation with MIRION engineers within one day shortly before the tests flights with the customer. Fig. 2 depicts the DJI M 600 Pro, the radiation sensor and analysis station as well as the integrated SKIDER system. The system evaluation was performed at two locations in France.

The ranged test showed that the anticipated range of 1 km could easily be achieved in line and non-line of sight conditions.
During line of sight conditions the communication range was at least 3.8 km.

The average delay was below 1s when a connection was established. During the non-line of sight test, the UAV flew about 1.7 km without data transmission. As soon as connectivity was recovered, the buffered data was transmitted at maximum data rate.