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been lowered down until it moved behind trees or the landscape, to rise up again, or to get activated, take o and go up in the air (Fig.12). Note that, prior to the experiment, we had received ight permission required by the amend-ed Civil Aviation Act, in the same way as in the case of the beyond line-of-sight tests of Puma AE.At present, we have not improved our system to carry out image transmissions from a drone beyond line-of-sight. However, we have a plan to conduct trials of image trans-mission using the 920 MHz band. Because the band is not so suitable for image transmission, we will develop and evaluate test systems for low quality/low rate image trans-mission.Currently, our wireless module is equipped with, in addition to a 920 MHz band wireless device, a 169 MHz band wireless device—a type of “unmanned vehicle image transmission system” newly approved by the MIC. We re-ceived a radio station license for the 169 MHz band device on June 14, 2017, soon mounting the device on a multi-rotor type drone. en, on June 17, 2017, although it was a short range such as dozens of meters, we successfully conducted the following trials using 169 MHz frequencies: the rst command transmission and telemetry reception between a drone and a ground station by direct commu-nications (1 hop); conduction of a drone ight by control signal linking by relayed communications (2 hop) via a relay drone. We will leave the details to other articles, and we are going to show our conclusions as follows: as ex-pected, the 169 MHz band is not so promising for a high transmission speed, and moreover, the number of available channels is around four maximum. However, with regard to transmission distances, we will be able to have a long free-space propagation distance from ground to high posi-tions in the air, which is far longer than in the 920 MHz or 2.4 GHz bands. So, the band could be used for backup links in the case where the radio wave in operation is inter-rupted or becomes unstable, and be eective for reliability improvement in drone operations in a visual beyond line-of-sight or radio beyond line-of-sight environment.2. Between-Flying-Objects Location Sharing TechnologiesNear-miss incidents of a drone with a manned helicop-ter have been reported recently. Such an incident could lead to a life-threatening accident to a helicopter pilot or pas-sengers—even if no human damages would occur on the drone side. Moreover, in the future situation of the air expected to be congested with a large number of drones ying for goods delivery or disaster missions, there would be a high risk of human or ground facility damages caused by drone collisions or crashes to the ground.For preparing for such risks, we developed a system that is useful for the avoidance of drone-to-drone or drone-to-manned aircra collisions, where drones or aircras share mutually location information using broadcast-type transmission protocols. We have been conducting proof-of-concept experiments using, similarly to the previously mentioned system, a 920 MHz band special small power radio station. We have named the system “Drone Mapper” [17] (Fig.13). Similarly to the previous system, this system has a multi-hop function and we can describe how it works, taking, as an example, the situation shown in Fig.13, as follows: Operator A does not have, in his line of sight, Drone B’ operated by Operator B. If Drone A’ operated by Operator A is in the line of sight of Drone B, Operator A is able to know the location of Drone B’ via Drone A (relayed by Drone A).Speaking from the technical point of view, the system is based on a ground-based “device-to-device communica-tion network technology” (Section 2-7), which has been FiF13　Drone mapper: flying objects’ location sharing systemSharing location /IDs between the flying vehicles of different or same typeOperator A(yourself)Operator B(another operator)Manned helicopterDrone A’ operated by operator ABLOSGetting the location of drone A’, B’, and a manned helicopterDrone B’ operated by operator BGetting the location of drone A’ and B’FiF12Field test of beyond line of sight relayed control using “Tough Wireless” (June and November 2016, June 2017, at New Aobayama Campus, Tohoku University, Sendai, Miyagi)Relaydrone(cable powered)20mControl stationEnvironment where an operator is unable to directly communicate with a target drone (BRLOS)Launching/lifting a target drone up in the air remotely from a BVLOS and at a time BRLOSTarget droneWe have successfully launched/lifted a drone up in the air remotely from a place beyond visual line of sight (BVLOS) and at a time beyond radio line of sight(BRLOS).Telemetry information of the target drone received through a relay drone672-9 Wireless Communication Technology for Small Unmanned Aircraft Systems ~Towards the deployment of IoT in the Sky~