Surface Velocity Estimation of Streams Using a 77 GHz Radar Unit

Relying on a multi-channel 77 GHz radar unit, a surface velocity measurement system for streams is introduced. By applying the frequency-modulated continuous-wave approach, the distance between the radar unit and the target, the angle-of-incidence of the radio wave signal, and the target velocity are determined. Thus, interfering reflections resulting from moving as well as stationary scatterers can be separated from the relevant target. Two approaches are analyzed, allowing either to estimate the surface velocity profile for the cross section of the channel, or to simultaneously determine the surface velocity and the height of the radar unit above the surface of the water. To verify the system concept, measurements were carried out under real environmental conditions, showing accurate results for both approaches.