LR-D1 altitude or distance sensor

The LR-D1 is a 24 GHz radar altimeter from Ainstein, a long-range altitude and distance sensor for large unmanned aircraft that need a height reading over any surface and in any weather.

Because it measures with radio waves, the LR-D1 is not tied to the barometric drift that affects low-altitude pressure readings, to the surface and light limits of laser rangefinders, or to the satellite signal strength that governs GPS height. The maker positions it for industrial UAVs of 85 kg and above, including very heavy lifters that carry water or cargo, tactical and ruggedized aircraft, reconnaissance and surveillance platforms, aerial targets, defense drones and geophysical surveying and terrain-mapping aircraft. It is also used to support advanced take-off and landing, where an accurate height above ground matters most.

The key figures are as follows. The sensor works in the 24 GHz band with 250 MHz of bandwidth, and the wide bandwidth is what gives precision at height. The altitude range is 0.7 m to 500 m with a stated precision of 0.365 m, and the update rate is 40 Hz, which is fast enough for a flight controller or flight-management loop to follow a descent or terrain-following profile. The field of view is 43° in azimuth and 30° in elevation, so the radar reports the strongest return within that cone. Below 0.7 m the unit is in its blind zone and the readings are volatile.

Each reading is accompanied by a signal-to-noise ratio, and the unit also reports an error code, for example for saturation at low altitude. The maker treats a ratio above 13 dB as a high-confidence measurement and one below that value as low confidence, so the host software can reject doubtful samples. The return depends on the size, material and angle of the surface, and other objects inside the field of view can cause errors. Flight tests were run at speeds up to 200 m/s, and the design allows to cope with high bank angles and sharp altitude changes.

For integration, the LR-D1 offers RS-232 and RS-422 serial interfaces and runs from a 10 V to 30 V supply, which covers 12 V and 24 V aircraft power buses. The dimensions are 112 mm x 102.5 mm x 29 mm and the mass is 300 g. The operating temperature range is -40 °C to +60 °C and the enclosure is rated IP67 by the maker's own testing. The front face must be mounted perpendicular to the ground below the aircraft and fixed so that it cannot move, with a clear field of view. Two units at the same frequency can interfere when mounted side by side, carbon fibre generally blocks the beam, and indoor tests produce multipath errors, so trials belong outdoors. Ainstein supplies a data sheet, a technical user manual, a CAD file, a firmware update tool and bench-test software on request, and its components are ITAR free with an EAR99 export classification.

Typical uses are height-above-ground sensing for landing and take-off, terrain following for survey aircraft, altitude hold over water or snow where optical sensors struggle, and height reference for high-speed target and reconnaissance drones.