All Weather Inc 8339 User manual

All Weather Inc. • 1065 National Drive • Sacramento, CA 95834 • USA • 800.824.5873 • www.allweatherinc.com
Model8339
CloudHeightIndicatorLaserCeilometer
User’s
Manual
Rev. M

Copyright ©2013–2021, All Weather, Inc.
All Rights Reserved. The information contained herein is proprietary and is provided solely for the purpose of
allowing customers to operate and/or service All Weather, Inc. manufactured equipment and is not to be released,
reproduced, or used for any other purpose without written permission of All Weather, Inc.
Throughout this manual, trademarked names might be used. Rather than put a trademark (™) symbol in every
occurrence of a trademarked name, we state herein that we are using the names only in an editorial fashion and to
the benefit of the trademark owner, and with no intention of infringement. All Weather, Inc. and the All Weather,
Inc. logo are trademarks of All Weather, Inc.
Disclaimer
The information and specifications described in this manual are subject to change without notice.
Latest Manual Version
For the latest version of this manual, see the User Manuals page under Support on our Web site at
www.allweatherinc.com/.
All Weather, Inc.
1065 National Drive, Suite 1
Sacramento, CA 95834
Tel.: [phone]
Fax: [phone]
Contact Customer Service
Phone support is available from 8:00am - 4:30pm PT, Monday through Friday. Call 916-928-1000 and ask for
“Service.”
Online support is available by filling out a request at www.allweatherinc.com/customer/support.html
E-mail your support request to [e-mail]

Model 8339 Ceilometer User’s Manual
Revision History
Revision
Date
Summary of Changes
G
2011 Aug 23
Added RS-485 communication, polling commands with CRC, reboot and laser
temperature control warning status bits.
H
2011 Oct 1
Corrected 8329 mode baud rate
J
2011 Oct 4
Enhanced description of grounding requirements during installation.
K
2014 Nov 20
Added cross-reference to status codes in Section 2.3.2 and simplified lens cleaning to
clean water
L
2016 May 26
Updated 8339-F-019/8339-G-019 wiring diagrams to add wire colors
M
2021 Feb 5
Added RS-485 surge suppression

Model 8339 Ceilometer User’s Manual
TABLEOFCONTENTS
1. OVERVIEW.........................................................................................................................1
1.1 Models ........................................................................................................................................1
1.2 Accessories.................................................................................................................................2
2. THEORY OF OPERATION .................................................................................................3
2.1 General Description....................................................................................................................3
2.2 Theory of Operation ...................................................................................................................3
2.2.1 Functional Description........................................................................................................4
2.3 Modules ......................................................................................................................................5
2.3.1 Optical Module ...................................................................................................................5
2.3.2 Data Acquisition Board.......................................................................................................8
2.4 Fault Detection..........................................................................................................................10
3. DATA COMMUNICATION.................................................................................................11
3.1 8339 Native Format..................................................................................................................11
3.1.1 Communication Parameters..............................................................................................11
3.1.2 Data Format ......................................................................................................................11
3.1.3 Poll Commands.................................................................................................................12
3.2 8339 Sky Condition Format......................................................................................................14
3.2.1 Data Format ......................................................................................................................15
3.3 8329 Format..............................................................................................................................16
3.3.1 Communication Parameters..............................................................................................16
3.3.2 Data Format ......................................................................................................................16
3.4 8339 ASOS ICD.......................................................................................................................17
3.4.1 Communication Parameters..............................................................................................17
3.4.2 8339 ASOS ICD Command Set........................................................................................17
4. UNPACKING AND INSTALLATION..................................................................................27
4.1 Unpacking.................................................................................................................................27
4.2 Installation ................................................................................................................................27
4.2.1 Mechanical Mounting.......................................................................................................28
4.2.2 Optional Heater/Blower....................................................................................................29
4.2.3 Ceilometer Lightning Surge Suppressor...........................................................................30
4.2.4 Ceilometer Data Connection.............................................................................................31
4.2.5 Ceilometer Power Connection..........................................................................................32
4.2.6 Final Steps.........................................................................................................................32
5. OPERATION.....................................................................................................................34
5.1 Power Up..................................................................................................................................34
5.2 Checkout...................................................................................................................................34
6. MAINTENANCE ................................................................................................................35
6.1 Periodic Maintenance ...............................................................................................................35
6.1.1 Window Cleaning —Monthly or as required...................................................................35

Model 8339 Ceilometer User’s Manual
6.1.2 Blower Check —Monthly................................................................................................35
6.1.3 Desiccant Replacement —Triannually............................................................................35
6.1.4 Blower Housing Cleaning —Annually............................................................................36
6.2 Fuse Replacement.....................................................................................................................36
7. TROUBLESHOOTING ......................................................................................................37
7.1 Using the Status Message.........................................................................................................37
8. REMOVAL AND REPLACEMENT ....................................................................................40
8.1 Removing Modules...................................................................................................................40
8.1.1 Data Acquisition Board.....................................................................................................41
8.1.2 Optical Module .................................................................................................................42
8.1.3 DIN Rail Components.......................................................................................................43
8.2 Replacing Modules...................................................................................................................44
8.2.1 Data Acquisition Board (Figure 18) .................................................................................44
8.2.2 Optical Module (Figure 19)..............................................................................................44
8.2.3 DIN Rail Components.......................................................................................................45
9. FIRMWARE UPDATES.....................................................................................................46
10. SPECIFICATIONS ..........................................................................................................47
11. WARRANTY....................................................................................................................49
12. DRAWINGS ....................................................................................................................50

Model 8339 Ceilometer User’s Manual
WARNINGS
Eye Safety
The 8339 Cloud Height Indicator (Ceilometer) uses an invisible IR laser
configured as Class I according to FDA regulation CFR Title 21, Section
1040.10. This standard is system-specific, meaning that it is possible to
reconfigure the system into a dangerous mode. In order to ensure continued
eye safety over the life of the product:
a) Never use external condensing optics devices, such as binoculars,
lenses, etc., to look into the output aperture. Also avoid reflections
from mirrors with condensing properties, i.e., mirrors with concave
curvatures. The Ceilometer is safe only as long as the beam remains
unmodified from its output form. Though the system is also safe
with the door opened, an interlock switch prevents the laser from
being fired without the door closed.
b) Never make modifications or adjustments to the Optical Module.
Fuses
Use only replacement fuses specified in the maintenance section of this
manual. In addition to observing the current rating, use only “slo blo” fuses.
Failure to do so may damage the system. If fuses blow repeatedly, a serious
condition is indicated.
Equatorial
Filter
An equatorial filter that prevents damage to the laser from exposure to
direct sunlight is installed on every 8339 Ceilometer. This filter causes no
degradation in performance.

Model 8339 Ceilometer User’s Manual
1
1. OVERVIEW
The Model 8339 Laser Ceilometer measures the height and thickness of up to four cloud layers
simultaneously to a distance of 25,000 vertical feet. It can also report vertical visibility.
Its precision makes it ideal for applications requiring the highest performance and reliability, such as
aviation and meteorological studies.
A laser pulse is emitted towards the zenith above the Ceilometer, and the backscatter is analyzed. The
laser pulse moves at speed of light, and the difference between the emission of the pulse and the return
of the backscattered signal is used to calculate the altitude of each cloud base and top.
Some cloud types have poorly defined borders or a sparse composition, and are much more difficult to
measure than others. Depending on the current and historical sky conditions, an adaptive algorithm
determines the frequency at which the pulses should be emitted to maintain accuracy.
Weather conditions such as heavy precipitation and low clouds can lead to reporting errors in other
Ceilometer designs. Proprietary algorithms and digital techniques developed by All Weather Inc.
based on 20 years of cloud detection research and manufacturing experience are are used by the
Model 8339 Ceilometer to provide accurate information even in difficult circumstances.
Sensing circuits and optimization algorithms control the pulse frequency, output power, and
temperature of the laser itself in order to extend its life dramatically.
The 8339 is enclosed in a NEMA 4X electro-polished 304 stainless steel package that will stand up to
the harshest environmental conditions from corrosive marine air to blowing desert sand. The 8339 is
designed to last.
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.
The serviceability design of the 8339 was influenced by our customers. Their input was used to
engineer the package and configuration of “Line Replacement Units” so that repairs can be
accomplished in 30 minutes or less.
1.1 MODELS
Three 8339 models are available.
Model
Description
8339-F
115 V AC
8339-FAA
115 VAC*
8339-G
230 V AC
*Measurement range fixed to 12,500 ft

Model 8339 Ceilometer User’s Manual
2
1.2 ACCESSORIES
The following accessories are available for the Model 8339 Ceilometer.
Part Number
Description
83395-00
Battery Backup Kit
83396-00
100–120 V AC Heater/Blower for use with 8339-F
83397-00
200–240 V AC Heater/Blower for use with 8339-G
M488261-00
Ceilometer Mounting Kit
M491742-00
Ceilometer Data Cable
M491745-01
50 ft Ceilometer Power Cable
(Ceilometer power connector to bare wires)
M491762-02
Heater/Blower Data and Power Cable
M491763-01
Service Port Cable
M028181-00
Desiccant

Model 8339 Ceilometer User’s Manual
3
2. THEORYOFOPERATION
2.1 GENERAL DESCRIPTION
The Model 8339 Ceilometer (also known as Cloud Height Indicator, or CHI) is designed for fixed
installation at airports, meteorological stations, or anywhere reliable cloud ceiling information is
required. The Ceilometer monitors sky conditions continuously and reports up to four detected cloud
bases and depths to an altitude of 25,000 feet above ground level. If the Ceilometer cannot “see”
beyond a height of 3,000 feet, meaning that vertical visibility is restricted but there is no discernible
cloud base, the Ceilometer outputs a vertical visibility value. Vertical visibility is defined as follows.
Extinction is given by:
z
eII
 
0
where σ is the extinction coefficient (corresponds to the water particulate density in the air). The
vertical visibility is then found by solving:

 visibilityvertical zdze
II
0
0
05.0

In other words, that distance where 95% of the initial laser beam has been extinguished by scattering.
The 8339 works in accordance with the principal of optical radar, or LIDAR. A laser pulse is emitted
at a maximum rate of 1 kHz vertically into the atmosphere, and the resulting backscattering is
analyzed for water density. Clouds are identified when the water density changes abruptly. Vertical
visibility is determined by integrating the near field water density pattern. Proprietary algorithms
enable the unit to achieve superior performance while still maintaining an eye-safe laser light level.
The 8339 is comprised of modular, field-replaceable units. Internal self-test routines identify faults
and isolate them to the module level.
! WARNING !
The Model 8339 Ceilometer is a Class I laser configuration, which is eye-safe in all
conditions except when viewed through optical instrumentation, such as binoculars
or any other condensers. Never view the optical radiation through such devices or
serious eye damage may result.
2.2 THEORY OF OPERATION
A laser pulse is emitted into the atmosphere by the transmitter, and a high-speed analog-to-digital
converter is used to record the backscatter returns to the receiver. The receiver is adjustable, so that
gains and response parameters can be varied in an adaptive sense. A number of pulse bursts are
obtained, depending on the current and historical sky conditions. Using the speed of light, the altitude
of the clouds may then be determined.

Model 8339 Ceilometer User’s Manual
4
Vertical visibility is determined by integrating the total water density in the near field with calibration
coefficients obtained by comparing the Ceilometer with visibility sensors and present weather sensors
that have been maintained in accordance with NBS and FAA guidelines.
A dirty window detector is used to control a heater/blower that keeps the optical windows free of dust,
water, and snow. When the Ceilometer windows reach a point where they require manual cleaning, an
alert is output over the communication bus. If the windows are not cleaned following the alert and the
accuracy of the collected data becomes questionable, the Ceilometer sends a failure message.
The “effective range” of the Ceilometer—the altitude above which the results are uncertain—is
continually monitored using sophisticated signal analysis techniques. In heavy fog, for instance, the
Ceilometer can only see through so much water droplet density before the laser beam has been
completely depleted (scattered into space). The effective range is useful to know, since there may be
clouds above that altitude that the Ceilometer cannot see.
Some clouds are much more difficult to detect than others, due, for example, to poorly defined borders
or a sparse composition. The proprietary algorithms used in the 8339 are adaptive to these conditions,
allowing the Ceilometer to provide accurate information even in difficult circumstances.
2.2.1 Functional Description
The 8339 Ceilometer is designed with interchangeable modules to make it straightforward to maintain
in the field (see Figure 1). Extensive internal self-testing identifies problems and provides detailed
information concerning the nature of the problem, including the specific module with which the
problem is associated.
Figure 1. Ceilometer Components