Definition
UAV (Unmanned Aerial Vehicle, unmanned aerial vehicle) is a drone that performs inspections, mapping, logistics, agriculture, security, and other tasks via remote control or autonomous flight. UAVs include multirotor, fixed-wing, vertical take-off and landing (VTOL) types, and can carry cameras, LiDAR, multispectral sensors, payloads, and more. They are classified by weight into micro, light, small, medium, and large types, each suitable for different airspaces and approval requirements.
UAVs achieve real-time image transmission, remote control, position reporting, flight data feedback, and cloud platform integration through 4G/5G IoT SIM cards. IoT SIM cards provide UAVs with wide coverage and low-latency aerial connectivity, supporting BVLOS (beyond visual line of sight) flight, long-distance inspections, and drone logistics applications.
Technical Features
UAVs are equipped with flight control, GNSS, obstacle avoidance, and image transmission modules. Cellular communication can serve as a primary link (BVLOS) or backup link, forming redundancy with image and data transmission. Drone cloud platforms require UAVs to report position, altitude, speed, and other data in real time, and IoT SIM cards must ensure stable connectivity. Low-altitude coverage and mobile scenarios place high demands on network quality.
Use Cases
UAVs are applied in power inspection, oil and gas pipeline inspection, surveying and mapping, agricultural plant protection, logistics delivery, security monitoring, emergency command, and weather modification. Typical scenarios include UAV inspection, real-time image transmission, beyond visual line of sight flight, and drone logistics. SimtoLink provides UAVs with IoT SIM cards, dedicated APNs, data plans, and drone solutions.
The onboard module reports the state of the aircraft
Here an unmanned aircraft means the machine that flies: airframe, flight controller, navigation, obstacle avoidance, payload, and communication module. If the IoT SIM is on the airframe, the uplink should describe that aircraft, not a router in a ground box. The smallest state set includes position, altitude, ground speed, heading, flight mode, and fix quality, plus the airframe id and the time. Multirotor, fixed-wing, and vertical takeoff and landing have different reasonable speed ranges for stall, hover, and cruise. One set of thresholds for "bad data" marks a fixed-wing's normal cruise as lost, or a multirotor's hover as a fault.
Payload data should be separate from airframe state. Camera, multispectral, and lidar files are large and can go later. Altitude and mode are immediate; if they arrive late they no longer help command. Module sleep, attach, and application reporting are three different things. A successful registration does not mean the flight controller has sent the state on its serial port. Antenna placement has to account for airframe blockage and gimbal motion. An antenna aimed straight down from the airframe may still work in a steep orbit. An antenna inside the battery bay often has throughput only near the takeoff field.
Weight class, the route, and where the SIM is enabled
Aircraft classes by weight map to different airspace and operating rules. Where the SIM is enabled has to follow the route, not the place it was purchased. If it is enabled only for local use at the takeoff and landing field, and the second half of the route needs roaming or another region, commands drop at the boundary. If the return logic depends on the link at that moment, the aircraft stops in the coverage hole. Low-altitude base-station changes are denser than on a road. The module should be allowed to reselect while moving, and it should store state on the aircraft during the handover and backfill by time once coverage returns.
The conditions of use also include a stated airspace and height limit for this flight, a lost-link action already loaded, and a mission sheet that says whether the control link or the cellular link is primary. Without a lost-link policy, cellular should not be the only means. Compared with a UAS, this page is about the module on the aircraft and the state it sends. Ground-station software and the airspace filing process belong at the system layer. A delivery mission should also separate "en route" from "the drop" in the state. The drop position comes from the fix at that moment. A point filled in after landing must not rewrite it.
Antenna facing, the altitude field, and a record that stops halfway
Mixing altitude fields is a common inspection error. The flight controller outputs height above the takeoff point, the platform checks the airspace ceiling as an elevation, and the aircraft is numerically "too high" or "never too high." The message should name the altitude reference. Pressure altitude drifts in strong weather. When it differs from satellite height, keep both, so a later review can tell a sensor problem from a link problem. Still sending a smoothed false position after fix quality has dropped makes the track look continuous when the satellites are already lost.
When the SIM does not cover the later part of the route, the record stops mid-way. If the platform treats the last point as the landing point, it marks an aircraft that is still airborne as mission complete. BVLOS flight has to separate "link lost" from "mission ended normally." When video and state share one SIM, keep the state interval first and send images after. Once images fill the channel, state stops too. The ground side sees a frozen picture and a frozen position, and it is easy to read that as a hover. If SIM-to-device binding was written from the device id used in a ground test, and the binding is not updated after the airborne module is replaced, the new module attaches and still cannot send application data.
After a propeller or a battery change, the center of gravity does not appear in the message, but vibration and attitude from the flight controller do change. Judging the airframe only by how often the link drops records a mechanical problem as a communications problem. When an inspection passes a tower again and again, transmitters on the tower can kick the fix for a short time. Keep the raw jump and mark the quality as worse. Smoothing the jump makes the wire clearance look acceptable the whole time. The time on a photo and the time on the state message have to line up. A one-zone offset labels the defect on the next tower. A position backfilled after landing must not rewrite a drop or photo coordinate that was already recorded.