3.4. Rain and Wind

Unlike conventional Doppler radars, whose accuracy can be significantly affected by rainfall, the VX60 uses advanced FMCW radar signal processing. This technology enables the instrument to distinguish between reflections from raindrops and reflections from the water surface. As a result, the VX60 can measure surface flow velocity reliably even during rainfall.

Wind generally has only a minor influence on measurement accuracy and can usually be neglected. The main exception is strong wind. Strong wind can generate surface waves that travel in a different direction than the main water flow. This may introduce deviations in the measured surface velocity.

In locations where strong wind is common, the following measures are recommended:

• Install the instrument at a sheltered location, if possible (for example, under a bridge structure or in a naturally protected river section).

• Avoid installation at wide, open sections where wind can generate significant cross-waves.

• Increase the filter duration (filter length) to improve measurement stability under fluctuating surface conditions. A longer filter duration reduces short-term fluctuations caused by wind-driven waves and improves overall measurement stability.