Fondriest Environmental now offers a completely optical solution for rainfall measurement applications. The RG-11 optical rain gauge from Hydreon does not rely on any mechanical, chemical, or conductive means to measure rainfall.
Instead, the compact unit constantly emits beams of infrared light within its clear, plastic lens. As precipitation falls onto the unit, the droplets make it possible for some of the light to escape. The RG-11’s optical sensor can detect this reduction in beam intensity and calculate the presence and size of rain droplets.
This optical solution overcomes many of the mechanical limitations of a tipping bucket rain gauge system. For one, the system can work well in mobile environments and be oriented in any direction. In fact, it’s the same technique used in rain-sensing windshield wiping controls on newer vehicles. Additionally, the optical technology avoids maintenance issues such as a collecting funnel becoming clogged with leaves or other debris.
The round shape of the external lens makes the unit essentially self-cleaning. However, the RG-11 can also detect imperfections on the surface, resulting from dirt, contaminants, and aging, and compensate readings accordingly.
The RG-11 is not quite as accurate as a tipping bucket rain gauge, but its low cost and compactness (about the size of a tennis ball) make it ideal for wet weather notification systems or remote rain gauges where periodic maintenance would be difficult or impossible.
The optical rain sensor can provide precipitation data in a number of formats to suit different applications. A DIP switch allows users to select from the following modes of operation:
The software that extrapolates this precipitation data is extremely sophisticated, but all processing is performed internally. This reliable, low-cost unit outputs simple, reliable precipitation readings for easy integration into any weather monitoring system.