Campbell SkyVUE Pro User manual

Revision:11/2020
Copyright © 2019 – 2020
Campbell Scientific, Inc.

Table of contents
1. General information 1
1.1 Packing list 1
1.2 General safety 1
1.3 Sensor unit safety 2
1.4 Laser safety 2
1.5 Electrical safety 3
2. Product overview 4
2.1 Introduction 5
2.1.1 Cloud height detection 6
2.1.2 Sky condition 6
2.1.3 Backscatter profile reporting 7
2.1.4 Mixing layer height 7
2.2 Optical measurement 8
2.2.1 Optical arrangement 8
2.3 Internal monitoring 8
2.4 Specifications 9
2.4.1 Measurement specifications 9
2.4.2 Mechanical specifications 9
2.4.3 Electrical specifications 10
2.4.4 Optical specifications 12
2.4.5 Environmental specifications 12
2.4.6 Communications specifications 12
3. Initial preparation and checks 13
4. Installation 14
4.1 Location and orientation 14
4.2 Grounding 15
4.3 Mounting the SkyVUE PRO 15
4.4 Tilt angle 16
4.5 Connectors and wiring 17
4.5.1 Base connectors 18
4.5.2 Wiring using supplied Campbell Scientific cables 19
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4.5.2.1 Power connections 20
4.5.2.2 Communications connections 21
4.5.3 USB connection 22
4.5.4 SDI-12 connection 22
4.6 Connecting the back-up battery 22
4.6.1 Removing the cover 23
4.6.2 Removing the enclosure lid 23
4.7 Bird spike kit 24
4.8 Storage information 26
5. Operation 27
5.1 Terminal mode 27
5.1.1 Entering/exiting the SkyVUE PRO terminal mode 27
5.1.2 Terminal mode commands general 28
5.1.3 Terminal mode command examples 29
5.1.4 Application command message types 44
5.1.5 MCFG command message types 46
5.1.6 Measurement and message intervals 47
5.1.7 Status command 49
5.1.8 Message polling 58
5.1.9 Loading a new operating system (OS) 59
5.1.10 Stratocumulus backscatter calibration 62
5.1.11 CRC-16 codes on terminal commands 64
5.1.12 Service command 65
5.1.13 Locked features 66
5.2 Restoring factory defaults 66
5.3 LED indicator 67
6. Messages 68
6.1 Data messages general 68
6.2 Checksums used in SkyVUE PRO messages 68
6.3 CS messages 69
6.3.1 MESSAGE 001 (no profile, no sky condition) 69
6.3.2 MESSAGE 002 (Profile, no sky condition) 73
6.3.3 MESSAGE 003 (no profile, sky condition) 76
6.3.4 MESSAGE 004 (profile, sky condition) — default message 78
6.3.5 MESSAGE 005 (no profile, sky condition, mixing layer heights) 82
6.3.6 MESSAGE 006 (profile, sky condition, mixing layer heights) 85
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6.4 CL31 messages 89
6.4.1 MESSAGES 101 - 106, (CL31 MESSAGE 1) 89
6.4.2 MESSAGE 005 (no profile, sky condition, mixing layer heights) 90
6.4.3 MESSAGES 107 - 112, CL31 Message 2 94
6.5 CT25K messages 98
6.5.1 MESSAGE 113, CT25K Data Message No. 1 98
6.5.2 MESSAGE 114, CT25K Data Message No. 6 101
7. Maintenance 103
7.1 General 103
7.2 Cleaning 103
7.3 Removing the cover 104
7.4 Removing the enclosure lid 105
7.5 Diagnostic LED indicators within the enclosure 105
7.6 Electrical safety testing 107
Appendix A. Measurement of the attenuated backscatter profile 108
A.1 Initial measurement 108
A.2 Backscatter onset height detection 108
A.3 Produce attenuated backscatter output message 109
Appendix B. Cloud height calculation 110
Appendix C. Sky condition algorithm description 111
Appendix D. Replacing the SkyVUE PRO PSU 113
Appendix E. SkyVUE PRO Laser/APD module replacement 115
Appendix F. SkyVUE PRO TOP board replacement 118
Appendix G. Self-diagnostic information 124
List of figures
FIGURE 2-1. Principle of operation 8
FIGURE 2-2. SkyVUE PRO dimensions 10
FIGURE 2-3. PSU types 11
FIGURE 4-1. Mounting base footprint 16
FIGURE 4-2. Setting the tilt angle 17
FIGURE 4-3. Connector layout 18
FIGURE 4-4. Cable connections 21
FIGURE 4-5. USB port 22
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FIGURE 4-6. Connecting battery 22
FIGURE 4-7. Removing the cover 23
FIGURE 4-8. Removing the enclosure lid 24
FIGURE 4-9. Ceilometer bird spike kit installed 25
FIGURE 4-10. Preparing the SkyVUE PRO for installing the bird spikes 25
FIGURE 4-11. Attaching bird spikes to the SkyVUE PRO cowl 26
FIGURE 5-1. Restoring factory defaults 67
FIGURE 5-2. LED indicator 67
FIGURE 7-1. Removing the cover 104
FIGURE 7-2. Removing the enclosure lid 105
FIGURE 7-3. Diagnostic LED indicators 106
List of tables
Table 1-1: Packing list 1
Table 4-1: Function of the connector pins for the mains connector 18
Table 4-2: Function of the connector pins for the blower/heater connector 19
Table 4-3: Function of the connector pins for the communications connector 19
Table 5-1: Summary of the terminal mode commands available 30
Table 5-2: Summary of applications and applied settings for SkyVUE PRO 45
Table 5-3: Summary of message ID and descriptions 46
Table 6-1: Most significant alarm word for CS messages 70
Table 6-2: Middle alarm word for CS messages 71
Table 6-3: Least significant alarm word for CS messages 72
Table 6-4: Most significant alarm word for CS31 messages 91
Table 6-5: Middle alarm word for CS31 messages 92
Table 6-6: Least significant alarm word for CS31 messages 92
Table 6-7: Most significant alarm word for CT25K messages 99
Table 6-8: Second alarm word for CT25K messages 100
Table of Contents - iv

1. General information
1.1 Packing list 1
1.2 General safety 1
1.3 Sensor unit safety 2
1.4 Laser safety 2
1.5 Electrical safety 3
1.1 Packing list
The following table lists the products shipped with the SkyVUE PRO.
Table 1-1: Packing list
Description Quantity
Ceilometer 1
Power supply cable 1
Data cable 1
Bolt, sleeve anchor 4
Cable, USB type A plug to type B plug, 2 m 1
4 mm Allen key 1
Calibration plate 1
1.2 General safety
This manual provides important safety considerations for the installation, operation and
maintenance of the SkyVUE™PRO. These safety considerations are classified into three levels:
WARNING:
Warnings alert the installer or user to serious hazards. Ignoring these warnings could result in
injury or death and/or irrevocable damage to the sensor unit.
SkyVUE™PRO (CS135) LIDAR Ceilometer 1

CAUTION:
Cautions warn of potential hazards. Ignoring these cautions could result in the sensor being
damaged and data being lost.
NOTE:
Notes highlight useful information in the installation, use and maintenance of this product.
These should be followed carefully in order to gain the maximum benefit from the use of this
product.
1.3 Sensor unit safety
The SkyVUE PRO sensor has been checked for safety before leaving the factory and contains no
internally replaceable or modifiable parts.
WARNING:
Do not modify the SkyVUE PRO unit. Such modifications will lead to damage of the unit and
could expose users to dangerous light levels and voltages.
WARNING:
Do not attempt to repair the SkyVUE PRO unit without consulting Campbell Scientific.
CAUTION:
Ensure that the correct voltage supply is provided to the sensor.
1.4 Laser safety
The SkyVUE PRO sensor incorporates an InGaAs laser diode which is rated as a class 3B device.
This is an embedded laser where the output from the sensor unit, through the optics, is
minimized to class 1M. This classification indicates that viewing of the beam with the naked eye is
safe but looking directly into the beam with optical instruments, e.g. binoculars can be
dangerous.
From the laser head the output has the following characteristics:
Maximum average power: 15.0 mW (through 50 mm)
Maximum pulse energy: 1500 nJ (through 50 mm)
Pulse duration: 100 ns
Pulse frequency: 10 kHz
Wavelength: 912 nm ± 5 nm
SkyVUE™PRO (CS135) LIDAR Ceilometer 2

Tested to: EN 60825-1:2014
Half angle divergence: 0.44 mrad
The sensor is marked with the following warning information:
INVISIBLE LASER RADIATION
DO NOT VIEW DIRECTLY WITH OPTICAL INSTRUMENTS
CLASS 1M LASER PRODUCT
WARNING:
Removing the laser module with the power applied to the SkyVUE PRO may expose the user
to hazardous class 3B laser radiation.
No attempt should be made to operate the laser module outside of the housing.
WARNING:
Annually, check that the laser warning label on the sensor is still visible and can be clearly
read.
When installing the sensor, avoid pointing the laser housing towards areas where binoculars
are in common use.
WARNING:
Use of controls or adjustments or performance of procedures other than those specified
herein may result in hazardous radiation exposure.
1.5 Electrical safety
Because the sensor is powered from potentially hazardous mains voltages, the power-supply
should be wired only by personnel qualified to install electrical equipment. For permanent
outside installations, this usually requires a certified electrician who is also familiar with local
electrical and safety legislation. Some general guidance is given in Connectors and wiring (p. 17),
but the responsibility for the installation lies with the installer.
The unit is tested for electrical safety before dispatch but may need subsequent testing according
to local practice.
NOTE:
The unit should only be serviced by trained personnel.
SkyVUE™PRO (CS135) LIDAR Ceilometer 3

WARNING:
Removal of electronic module covers or connectors while the unit is powered will expose the
operator to potentially hazardous voltages and risk damage to the sensor.
The SkyVUE PRO has electrical and laser warning labels on the exterior and interior of the unit.
It is recommended that the hood and access panel door are not opened in conditions of rain,
hail or snow.
Isolate the sensor before removing internal components, including the cover to the avalanche
photodiode (APD) module. Only trained personnel should disassemble the instrument.
Mains connectors are shrouded to prevent touching of the contacts. The mains supply should be
isolated when connecting and disconnecting the cables to the sensor.
Where an isolator switch is fitted, this shall be a two-pole isolator, located as near to the sensor
as possible.
The SkyVUE PRO must be properly grounded by a licensed and qualified electrician to protect
against voltage leakage shock risk (Grounding (p. 15)).
Campbell Scientific recommends that RCD protection units be used with all sensors. See Power
connections (p. 20) for further information.
Mains powered heaters are enclosed to prevent contact.
CAUTION:
When powered, the heaters may operate automatically and without warning. They may
remain hot when not powered. Follow the isolation precautions, to avoid shock and burn
hazards.
The sealed battery has cables and protected connectors to prevent shorts. Avoid shorting the
battery to protect it from damage and to avoid burns to personnel through contact with hot
surfaces.
2. Product overview
2.1 Introduction 5
2.2 Optical measurement 8
2.3 Internal monitoring 8
2.4 Specifications 9
SkyVUE™PRO (CS135) LIDAR Ceilometer 4

2.1 Introduction
The SkyVUE PRO is a light detection and ranging (LIDAR) ceilometer that emits short pulses of
near infrared light into the atmosphere from a semiconductor laser. The pulses of infrared light
are scattered back by aerosols including cloud droplets. The time between transmission of the
pulse and the return signal gives the range, and therefore height, of the scattering aerosols. The
variation in the strength of the back-scattered light signal with height gives a profile of scatter
coefficients and allows identification of cloud bases. If significant scattering is detected without a
defined cloud base, then a vertical visibility can be calculated.
The control system of the SkyVUE PRO is divided into three modules, DSP, TOP and PSU as
follows:
DSP (Digital Signal Processor) is the main data processing and communications unit of the
SkyVUE PRO. It hosts two separate time keeping circuits that are cross checked. An alarm is
triggered if the circuits disagree.
SkyVUE™PRO (CS135) LIDAR Ceilometer 5

TOP (top of the unit) provides safety shutdown features such as over and under laser output
level. It also contains the calibration circuitry and dirty windows system.
PSU (Power Supply Unit) controls the power supply including battery charging and deep
discharge protection.
The SkyVUE PRO has a rugged environmental enclosure that protects the instrument from the
harshest conditions and will measure the atmosphere with high stability and repeatability.
2.1.1 Cloud height detection
A scatter profile is measured as described in Measurement of the attenuated backscatter profile
(p. 108).
Cloud height detection is carried out as described in Cloud height calculation (p. 110). Up to four
cloud heights can be detected.
If clouds are not detected, the SkyVUE PRO will give one of these reports:
lNo significant backscatter.
lFull obscuration determined but no cloud base detected. This is reported if the criteria for
detecting cloud base is not met but the integrated scattering coefficient reaches the limit
of vertical visibility below a set height limit. The default value is 2000m (6560ft) but can be
changed by the user. The height at which this occurs is given as vertical visibility.
lSome obscuration detected but determined to be transparent is reported if scattering is
detected but no cloud is detected and the calculated vertical visibility exceeds a set height
limit.
If no cloud is detected but significant scattering is detected below 50m (160ft), then vertical
visibility is set to 0.
2.1.2 Sky condition
Sky condition is an assessment of cloud cover measured in units of eighths known as oktas. The
number of oktas is the density of cloud in eighths of that layer. The SkyVUE PRO can report up to
five layers of cloud when reporting sky condition. The algorithm used in the SkyVUE PRO follows
guidance in the ICAO 9837, Manual on Automatic Meteorological Observing Systems at
Aerodromes.
Sky condition is not an instantaneous measurement. It is based on cloud data for the previous 30
minutes, with cloud detection in the previous 10 minutes given an extra weighting. Therefore, sky
condition is not available until sufficient data has been collected. See Sky condition algorithm
description (p. 111) for more detail.
SkyVUE™PRO (CS135) LIDAR Ceilometer 6

2.1.3 Backscatter profile reporting
Several possible data messages give the two-way attenuated backscatter profile. This consists of
2048 groups of five-character values (10,240 characters in total). Each character is 8 bits long and
therefore each 5 figure group is 40 bits. They are given as signed two complement integers and
numbers greater than 239–1 represent negative integers.
Therefore, each group actually represents negative, a value between –239 to +(239–1), rather than
0 to (240–1), which would be the case for unsigned, positive, 40-bit integers.
Apply the following two-stage process to correct the decimal value:
1. Convert the hexidecimal characters to a decimal number.
2. If the number resulting from this conversion is greater than 1048575, subtract
1,099,511,627,776, which is 240.
To use this backscatter coefficient in units of sr-1 m-1, the sensor multiplies the calculated decimal
number by a factor of 10-8. The values are scaled by the Attenuated_SCALE parameter, see
Table 5-1 (p. 30).
NOTE:
The last two values of the profile will always be zero. They are beyond the 10 km (32,800 ft)
range of the instrument.
NOTE:
The profile is not corrected for tilt angle even if cloud heights are corrected.
2.1.4 Mixing layer height
A Mixing Layer Height measurement option is available. This retrieves the height of the mixed
aerosol layer by applying the gradient method to the ceilometer backscatter signal. This
approach, based on the operational algorithm used by KNMI, searches for the drop in
backscatter associated with the transition from boundary layer aerosols to free troposphere. Since
the signals measured depend on the type and amount of aerosol present as well as the
background light level, the accuracy of the method varies, and therefore a quality factor is
assigned that indicates the confidence in the reported layer height. The module is also capable
of indicating the top of residual layers and aerosol layers aloft. To activate this option please
contact Campbell Scientific.
This is a guide to how well the mixing layer is defined on a scale 1 to 3 (3 is best). It is determined
by the magnitude of the difference between the average backscatter over a distance below the
MLH and the average backscatter over a distance above the MLH.
SkyVUE™PRO (CS135) LIDAR Ceilometer 7

Haij, M.J. de, H. Klein Baltink and W.M.F. Wauben: Continuous mixing layer height
determination using the LD-40 ceilometer: a feasibility study, Scientific Report WR 2007-01,
KNMI, De Bilt, 2007."
2.2 Optical measurement
FIGURE 2-1. Principle of operation
2.2.1 Optical arrangement
The SkyVUE PRO uses a single split lens design that increases optical signal-to-noise ratio, while
maintaining Class 1M eye safety by integrating larger optics into a compact package (see FIGURE
2-1 (p. 8)). Half of the lens is used by the transmitter, and the other half is used by the receiver.
This design provides an alternative to traditional two lens or common-optics designs. The optical
isolation of traditional biaxial systems is maintained to increase detector sensitivity, while the low
overlap onset height of common-optics systems is incorporated to allow measurements at close
ranges.
2.3 Internal monitoring
The SkyVUE PRO monitors window contamination, key voltages and currents, internal
temperature and relative humidity, and other parameters relevant to its performance. Data
SkyVUE™PRO (CS135) LIDAR Ceilometer 8

messages (see Operation (p. 27)) include this information allowing remote diagnosis of the
SkyVUE PRO condition. In addition, a special status message can be polled.
2.4 Specifications
2.4.1 Measurement specifications 9
2.4.2 Mechanical specifications 9
2.4.3 Electrical specifications 10
2.4.4 Optical specifications 12
2.4.5 Environmental specifications 12
2.4.6 Communications specifications 12
2.4.1 Measurement specifications
Maximum reporting range: 10 km (32800 ft)
Minimum reporting resolution: 5 m (15 ft)
Hard target range accuracy: ± 0.25% ± 4.6 m (15 ft)
Reporting cycle: 2 to 600 s
Cloud layers reported: Up to four layers reported
2.4.2 Mechanical specifications
Height: 1000 mm (39.3 in)
Width: 327 mm (12.8 in)
Depth: 281 mm (11 in)
Total weight: 33 kg (72 lb), excluding cables
Shipping weight: 58 kg (128 lb)
SkyVUE™PRO (CS135) LIDAR Ceilometer 9

FIGURE 2-2. SkyVUE PRO dimensions
2.4.3 Electrical specifications
Power required: Nominal 115 VAC (106 to 137 VAC) or nominal 230 VAC (216
to 253 VAC) (automatic selection), 47 to 63 Hz, 470 W total
maximum
Heater:
Hood heater: 270 W, maximum
Internal heater: 120 W, maximum
Supply voltage: Specified at time of order
Fuses: Current models use HBC SA(T); older models used the
following:
AUX fuse: HBC 5A (T)
SkyVUE™PRO (CS135) LIDAR Ceilometer 10

PSU fuse: HBC 500 mA (T)
All fuses are 5 x 20 mm slow blow (T) and are the same for
both 115VAC and 230VAC.
CAUTION:
The fuse values used must match the design of power supply unit.
Battery: Internal 12V, 7Ah sealed lead-acid battery provides 2 hour
measurement without the blower/heater. The power supply is
equipped with a system to prevent deep discharge of the
battery.
The SkyVUE PRO uses positive temperature coefficient (PTC) heaters within its design. These
heaters are self-regulating, simplifying the internal design of the sensor and improving safety.
Due to the nature of these devices, the SkyVUE PRO takes a higher current during start up. The
SkyVUE PRO takes up to 1 KW for the first few seconds of operation, dropping off quickly to its
normal operating power after a minute. In cold environments, the power consumption of the
SkyVUE PRO may be as high as 470 W. In warmer environments, it may be as low as 200 W.
The heaters are resistive, which is advantageous when connected to generators or when current
consumption is important.
FIGURE 2-3. PSU types
SkyVUE™PRO (CS135) LIDAR Ceilometer 11

2.4.4 Optical specifications
Pulse duration: 100 ns
Pulse frequency: 10 kHz
Wavelength: 912 ± 5 nm
Half-angle laser divergence: 0.35 mrad
Field of view: 1.5 mrad
Laser lifetime: 10 years typical
Eye safety class: 1M
2.4.5 Environmental specifications
Standard operating
temperature range: –40 to 60 °C (excluding battery)
Battery temperature range: –20 to 50 °C (alternative battery types available)
Relative humidity range: 0 to 100%
IP rating: IP 66
Maximum wind speed: 55 m/s
2.4.6 Communications specifications
Supported serial settings: 8 bits, no parity, 1 stop bit (default)
7 bits, even parity, 1 stop bit
7 bits, odd parity, 1 stop bit
Supported data rates: 300 baud 19200 baud
600 baud 38400 baud
1200 baud 57600 baud
2400 baud 76800 baud
4800 baud 115200 baud (default)
9600 baud
Supported standards: RS-232 (default)
RS-485 full duplex
RS-485 half duplex
SkyVUE™PRO (CS135) LIDAR Ceilometer 12

Signal voltage levels:
Minimum value Nominal value Maximum value
RS-232 communications
RS-232 input threshold low 0.8 V 1.5 V –
RS-232 input threshold high – 2.0 V 2.4 V
RS-232 input absolute maximum –15 V – +15 V
RS-232 input resistance 12 KΩ – –
RS-232 output voltage low – – 0.4 V
RS-232 output voltage high (into 3 KΩ) 4.4 V – –
RS-485/422 communications
RS-485/422 input threshold voltage –0.2 V – +0.2 V
RS-485/422 output (unloaded) – – 5V
RS-485/422 output (load 50 Ω) 2 V – –
Maximum voltage at any terminal –7 V – +7 V
USB Service Port USB1.1 and 2.0 compatible, fixed 115200 baud.
3. Initial preparation and checks
The following steps will provide basic familiarization with the SkyVUE PRO and perform basic
functionality checks. To do these, remove the cover and enclosure lid and connect the battery
(see Connecting the back-up battery (p. 22)). Connect the hood heater plug (FIGURE 4-3 (p. 18)
WARNING:
The laser begins operating as soon as the battery is connected. Do not point the laser in any
direction where it could be viewed with magnifying optics.
The green LED visible from above should flash once every 10 seconds (see FIGURE 5-2 (p. 67)).
Connect the SkyVUE PRO USB port (see FIGURE 4-5 (p. 22)) to a computer and use a terminal
emulation program to set to 115200 baud, 8N1 bits/parity settings.
SkyVUE™PRO (CS135) LIDAR Ceilometer 13

The computer should identify the USB connection and allocate a port number. Enter the port
setting in the terminal emulator program. Older computer operating systems may need
upgrading or additional software.
The SkyVUE PRO will output message type 004 (default) every 30 seconds (see CS messages (p.
69)).
Use the open 0 command to open the terminal mode. You should now see the prompt CS135>.
Type Status to see the sensor status information described in Status command (p. 49). If using
date/time information, checked it since the date/time can drift up to ±14 seconds per day.
If the unit has been in storage or transit for more than a few months, the clock battery may be
discharged. However, it will charge from the back-up battery or mains power.
Use the Close command to exit the terminal mode. It will close automatically after 10 minutes of
inactivity.
If you are not installing the unit and connecting mains power, you should disconnect the battery
to avoid it being discharged.
4. Installation
4.1 Location and orientation 14
4.2 Grounding 15
4.3 Mounting the SkyVUE PRO 15
4.4 Tilt angle 16
4.5 Connectors and wiring 17
4.6 Connecting the back-up battery 22
4.7 Bird spike kit 24
4.8 Storage information 26
4.1 Location and orientation
The SkyVUE PRO measures environmental variables and is designed to be located in harsh
weather conditions. However, there are a few considerations to take into account if accurate and
representative data from a site are to be obtained.
SkyVUE™PRO (CS135) LIDAR Ceilometer 14

To reduce the service frequency with the unit, place the SkyVUE PRO away from sources of
contamination. More regular maintenance will be required when the instrument is placed in
areas where contamination is unavoidable or where measurements may be safety related.
Take care that the orientation allows tilting in whatever direction is desired.
WARNING:
If installing at an airport, check and follow local guidance for allowed locations for a non-
frangible object 1 m (3.2 ft) tall. Please contact Campbell Scientific if frangible fittings are
required.
4.2 Grounding
The SkyVUE PRO must be properly grounded by taking a ground wire with a minimum cross
sectional area of 16mm2(0.62in) and maximum length of 10m (32.8ft) from the brass
grounding boss to an adequate grounding point. FIGURE 2-2 (p. 10) shows the location of the
grounding boss.
4.3 Mounting the SkyVUE PRO
Mount the SkyVUE PRO by bolting to a firm, level foundation. When bolting down, ensure the
SkyVUE PRO can tilt in all desired directions. FIGURE 4-1 (p. 16) shows the mounting footprint. If
a suitable surface does not already exist, construct a concrete foundation, at least 600mm
(23.6in) square and 600mm (23.6in) deep, by using the following procedure:
1. Drill four 12mm (0.47in) diameter holes using the mount base as a template (see FIGURE
4-1 (p. 16)) to a depth of 77mm (3.03in).
2. Clean the holes of all debris.
3. Place washers and nuts on the ends of the wedge anchors supplied (to protect the threads
during installation).
4. Hammer the wedge anchors into the holes until the start of the threads are below the
surface.
5. Tighten the nuts until about 25mm (0.98in) of thread protrudes above the surface.
6. Remove the washers and nuts from the protruding length screw, then lower the SkyVUE
PRO into place.
7. Secure the SkyVUE PRO with the washers and nuts.
SkyVUE™PRO (CS135) LIDAR Ceilometer 15