DJI D-RTK 3 Multifunctional Station

One box that does three jobs. Set it over a known point and it is a base station. Put it between the aircraft and the pilot and it is a relay that pushes the transmission link out to 40 km. Put it on a pole and it is a survey rover you walk points with. 1.26 kg, IP67, and it runs a working day on its own battery.

Rover accuracy, with the condition attached

The ppm term is the part people skip. It is error that grows with baseline length, so a figure quoted without the distance it was measured over is not a figure at all. At a 10 km baseline the 1 ppm adds a centimeter on its own.

Three modes, and when each one earns its place

• Base Station. Over a known point, broadcasting corrections to the aircraft. This is the mode that makes a mapping flight repeatable rather than merely accurate on the day.
• Relay Station. Sited between pilot and aircraft to extend the link. DJI publishes 40 km maximum unobstructed to a Matrice 400 under FCC. Take "unobstructed" literally: it is a line of sight number, not a range you plan a corridor job around.
• Rover Station. On a pole, walking points. It replaces a separate GNSS rover for occasional control and check shots, which is what makes this better value than its price suggests if you already fly DJI.

Specification, as DJI publishes it

Four constellations on triple frequency plus L-Band matters most where the sky is half blocked. Under canopy, in a street canyon, or against a cut face, the number of satellites a receiver can actually hold is what decides whether you get a fix at all, and the accuracy figure above assumes you got one.

What is in the box

• 1x D-RTK 3 Multifunctional Station
• 4x spare OcuSync directional antennas
• 1x USB-A to USB-C cable
• Hard transit case