Laser Ceilometer Model 8340

Overview

The 8340 Laser Ceilometer measures cloud height and thickness, in addition to vertical visibility, detecting up to four cloud layers simultaneously to a distance of 40,000 vertical feet. Its precision makes it ideal for applications requiring the highest in performance and reliability, such as aviation and meteorological studies.

A laser pulse is emitted into the atmosphere and backscatter analyzed. Using the speed of light, the height of each cloud base and top is determined. Due to poorly defined borders or a sparse composition, some clouds are much more difficult to measure than others. Depending on the current and historical sky conditions, an adaptive algorithm determines the number of returns needed to maintain accuracy.

Accuracy by Design

Accurate measurement of cloud height and thickness in all weather conditions, including heavy precipitation and low clouds, can cause serious errors in other ceilometers. Proprietary algorithms and digital techniques from 20 years of cloud height detection research and manufacturing are applied, allowing the 8340 ceilometer to provide accurate information even in difficult circumstances.

Long Life

Sensing circuits and optimization algorithms control the pulse frequency, output power and temperature of the laser itself in order to dramatically extend its life.

Extensive Self-diagnostics

An array of self-tests executed in the background during operation detects faults and reports them, along with identifying the replaceable module associated with the fault. Errors are reported both visibly in the sensor and electronically through the output string.

Designed by Our Customers

Quickly diagnosing a failed module is only one part of quickly restoring operational readiness. The serviceability design of the 8340 was influenced by our customers. Using their input to engineer the package and configuration of “Line Replacement Units,” repair can be accomplished in 30 minutes or less.

In addition, the 8340 is enclosed in a NEMA 4X stainless steel package that will stand up to the harshest environmental conditions thrown at it. From corrosive marine air to blowing desert sand, the 8340 is designed to last.

Solid Reputation

Over the years, AWI has developed a reputation for accuracy and reliability and is the preferred development partner of the FAA. In addition to supplying over 1,800 ASOS, AWOS, and AWSS systems to the FAA, NWS, and Department of Defense, our solutions also meet the stringent requirements of international standards organizations around the world, including the ICAO, WMO, and Transport Canada.

Performance

• Measurement range to 40,000 ft.
• Resolution 12.5 ft.
• Accuracy ±20 ft. over full range
• Cloud layers up to four, base and depth
• Measurement cycle configurable to 30, 60, or 120 second sampling/reporting interval; can be set to automatically switch to 180 second interval when no clouds are detected

Principle of Operation

• LIDAR pulsed diode, InGaAs
• Wavelength 905 nm ±10 nm
• Pulse width 50 ns
• Collector type Si Avalanche Photodiode, variable gain, temperature compensated
• Optics side-by-side optical channels

Safety

• Laser safety FDA Class I, 21 CFR1040

Electrical

• Power 95-240 VAC
• Frequency 47-64 Hz
• Power consumption
  • Electronics 100 W max.
  • Heaters/Blower (optional) 600 W max.
  • Battery backup (optional) ceilometer electronics only, built-in charger

Mechanical

• Dimensions
  • Ceilometer 19" H x 9" D x 16" W
  • with Heater/Blower 27" H x 20" D x 16" W
• Weight
  • Ceilometer 43 lbs. (19.5 kg)
  • Heater/Blower 18 lbs. (8 kg)
• Mounting single leg pedestal; 2½” pipe, unistrut mounted

Environmental

• Operating -40° C to +60°C
• Storage -50° C to +70°C
• Relative humidity 0-100%, condensing
• Enclosure
  • Ceilometer NEMA 4X stainless steel
  • Heater/Blower aluminum

Communication

RS-232 cloud detection, vertical visibility, sky condition algorithm, system status

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