Forward Scatter FD70 Series
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Forward Scatter FD70 Series Features • Visibility up to 100 km (62 mi) • Precipitation type identification, intensity, and accumulation • Droplet size distribution and reflectivity • Exceptional precipitation detection sensitivity • Superior liquid/frozen differentiation • Optimal forward scatter angle 42° • Look-down geometry to minimize measurement disturbances Innovative Technology The novel use of a single thin light sheet instead of the conventional light cone results in a high detection sensitivity. This enables a scatter-properties analysis of each single particle and allows the detection of even the smallest drizzle droplets. The particle size and fall speed distributions provide additional information, enhancing precipitation type identification. The receiver measures the forward scattered light at an angle of 42° with a very high sampling rate and powerful signal processing. The measurement arrangement and method is patent pending. Visibility Measurement FD70 Series provides the most representative extinction coefficient (EXCO) determination possible with the forward scatter technology. The visibility-reducing effect of precipitation is reliably calculated using scatter-properties analysis, allowing the reporting of meteorological optical range (MOR) even in the most challenging conditions. FD70 Series covers all application needs, including measurement performance and capability requirements for runway visual range (RVR). Precipitation Measurement Due to its innovative technology, FD70 Series reliably detects and identifies precipitation types that have been challenging for conventional technologies. • Drizzle • Rain • Snow • Snow grains • Ice crystals • Ice pellets • Freezing drizzle • Freezing rain • Snow pellets • Hail • Fog • Mist • Haze 1) Available in FD7IP 2) In addition to listed types, reports a variety of mixed precipitation types Reliable in All Weather FD70 Series has multiple features to ensure reliable operation even in extreme weather conditions. Effective hood heating and proven look-down geometry protect the sensor windows against external disturbances. These are complemented with independent optical path monitoring and window contamination compensation. Self-diagnostics and modular design enable short service times. For critical operations, such as airport use, FD70 Series provides redundancy of data communication. FD70 Series complies with ICAO, FAA, and WMO requirements, and uses the WMO and NWS weather codes in reporting. Calibration Traceability To ensure specified performance, Vaisala continuously compares calibrated FD70 units against reference sensors in the Vaisala outdoor test field. Every delivered unit can be traced back to this set of calibrated reference sensors. • FD71 for visibility • FD71P for visibility, present weather

Operating Environment Measurement Specifications Operating principle Look-down forward scatter Light source Near-infrared Operating temperature, extended -55 ... +65 °C (-67 ... +149 °F) (optional) Storage temperature -55 ... +65 °C (-67 ... +149 °F), non-condensing environment Operating humidity 0 ... 100 %RH Reporting uncertainty in operational ±10 % or ±1 m at 1 m ... 10 km 1) Fulfills ICAO Annex 3: ±50 m (164 ft) up to 600 m (1968 ft) Present weather identification Drizzle, rain Snow, snow grains, ice crystals Ice pellets, freezing rain, freezing drizzle Snow pellets, hail Fog, mist,...