Model 8365-A Dual Technology Visibility Sensor

Overview

The 8365-A Dual Technology Visibility Sensor measures transparency of the atmosphere and calculates its extension coefficient and meteorological optical range (MOR) values. Using both direct attenuation and forward scatter technologies, the 8365-A can measure airborne particle sizes once available only from a transmissometer, while having the reliability and cost-effectiveness of a forward scatter visibility sensor. Its precision makes it ideal for applications requiring the highest in performance and reliability, such as aviation and meteorological studies.

The Model 8365-A determines visibility by measuring the optical extinction coefficient of a beam of light as it passes through a known volume of air. Any particles in the air such as fog, rain, or snow will affect the extinction coefficient. This value can then be transmitted to an external computer in its unaltered form or translated into an equivalent MOR value in miles or kilometers covering a range of 33 feet to 20 miles (10 meters to 32 kilometers).

In AWOS systems, the extinction coefficient value is sent to the Model 1190 Data Collection Platform (DCP), which passes the value along with sensor status information to the Model 2090 Central Data Processor (CDP). The CDP then calculates visibility, variable visibility, and RVR (international systems only) over a visibility range of 33 feet to more than 20 miles.

When used in AWOS systems, the 8365-A sensor does not require the optional Handheld Terminal; all setup, test, and calibration functions are accessible from the AWOS DCP's built-in keypad and display. Other AWOS features include support for a Day/Night sensor and an ambient light sensor (ALS), which is required for RVR applications. For 220VAC applications, a transformer kit is available to allow the sensor (which normally operates at 110V, 60 Hz) to operate from a 220V, 50 Hz AC supply.

Dual Technology Visibility Sensor

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Performance

• Measurement range (MOR) 33 feet to 20 miles (10 meters to 32 kilometers)
• Accuracy ±10%
• Output interval 10 seconds or 1, 5, 10 minutes
• Averaging interval 3, 5, 10 or minutes
• Measurement MOR or extinction coefficient
• Units kilometers or miles
• Baud rate 300, 1200, 2400, 4800 or 9600 bps

Principle of Operation

• Dual technology both direct attenuation and forward scatter techniques        
• Light source Infrared emitting diode
• Wavelength 865nm ±35 nm
• Detector Silicon photodiode
• Principle scatter angle 35°

Electrical

• Power 115 VAC or 240 VAC with step-down transformer option
• Frequency 50-60 Hz
• Power consumption 200 VA typical
• Battery backup (option) 5 AH, 12 VDC (heaters not supported)

Mechanical

• Dimensions
  • Sensor assembly 61" L x 19" W x 21" H (1549 x 483 x 533 mm)
  • Control unit 16" H x 14" W x 8" D (400 x 350 x 200 mm)
• Weight 74  lbs  (33 kg)
• Mounting
  • Sensor assembly 2½ inch diameter mast
  • Control unit unistrut

Environmental

• Operating -40° C to +55°C
• Storage -50° C to +70°C
• Relative humidity 0-100%, condensing
• Wind speed up to 120 knots
• Hail up to ½ inch diameter
• Ice build-up up to ½ inch per hour
• Elevation -100 to 10,000 feet ASL (-30 to 3030 meters ASL)
• Enclosure NEMA 4x fiberglass

Communication

• RS-232, RS-485

Ordering Information

• 8365-A Dual Technology Visibility Sensor, 115 Vac; includes sensor assembly and control unit
• M403326-00 Day/Night sensor assembly (required)
• M488171-01 Ambient Light Sensor (ALS) kit
• M488173 Unistrut mounting hardware (control unit)
• M488174 230 Vac conversion kit
• T600503 Signal cable, specify length
• M492557 Power cable, specify length
• M104744 Calibrator
• 83503-A 10' mast (sensor assembly)
• M488150 Grounding kit
• M488175 Handheld Terminal kit
• 11903 Backup battery kit

U.S. Patent 5,373,367 Multiple Angle and Redundant Visibility Sensor

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