SF30 altitude or distance sensor

The SF30 is a laser altimeter and rangefinder from LightWare, sold as the SF30/D with a 200 m range. It is a single-beam laser sensor that measures the distance from an unmanned aircraft to the surface below, giving real-time height above ground level (AGL) for flight control, landing assistance and terrain following.

The sensor uses a 905 nm laser and a time-of-flight measurement on a single beam. Measuring range is 0.2 m to 200 m (0.6 ft to 656 ft) on a large target of 80 percent reflectivity, so the usable distance on darker or smaller surfaces will be shorter and should be tested for the intended terrain. The update rate is configurable from 39 up to 20,000 readings per second. A high rate gives the flight controller fresh height data for fast descents and landings, while a lower rate allows more averaging for stability. Over water, the maker documents altitude measurement that relies on the high update rate and on first-pulse and last-pulse detection, which helps when the beam is partly reflected by the surface and returns from below it.

Physically the unit is compact and light: 30 mm x 56 mm x 50 mm and about 31.5 g. It is an open-frame unit with a rating of IP40, and its front face is rated IP65, so the installer should shelter the body from moisture and dust inside the airframe and leave the optical window clear of obstruction.

Integration is through USB, serial (UART) and I2C. The I2C bus is 3.3 V logic and tolerates 5 V, which allows direct connection to most autopilot and companion computer ports. The maker lists compatibility with PX4, ArduPilot, Arduino and Raspberry Pi, and with its own LightWare Studio software for configuration and viewing. An aluminum stand kit is listed as an optional accessory.

The maker gives no certification for the sensor. Its single narrow beam suits altitude hold, precision landing support, terrain following and obstacle distance checks on multirotors, helicopters and fixed-wing UAVs, and in general any installation that needs a light and fast distance measurement to the ground.