Vaisala CT25K User Manual
CEILOMETER
CT25K
User’s Guide
CT25K-U059en-2.1
26 February 1999
Vaisala 1999
© Vaisala 1999
No part of this manual may be reproduced in any form or by any means,
electronic or mechanical (including photocopying), nor may its contents be
communicated to a third party without prior written permission of the
copyright holder.
The contents of instruction manuals are subject to change without prior
notice.
Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
Contents
LIST OF FIGURES............................................................................................................ IV
INTRODUCTION TO M ANUAL ........................................................................................ VII
VALIDITY OF T HIS M ANUAL.........................................................................................VIII
SAFETY SUMM ARY.........................................................................................................IX
1. GENERAL INFORMATION....................................................................................... 1
1.1 Product Overview.......................................................................................... 1
1.2 Specifications................................................................................................ 3
1.2.1 Mechanical................................................................................... 3
1.2.2 External Connector J1 - Window conditioner ................................ 3
1.2.3 External Connector J2 - Power inpu t ............................................ 3
1.2.4 Output Interface ........................................................................... 4
1.2.4.1 External Connector J3 - Data line................................................. 4
1.2.4.2 External Connector J4 - Mainte nanc e li ne .................................... 6
1.2.5 Modem Options ............................................................................ 6
1.2.5.1 Modem board DMX5 5................................................................... 6
1.2.5.2 Modem board DMX5 0................................................................... 7
1.2.5.3 ANet Interface DMX611............................................................. 7
1.2.6 Transmitter................................................................................... 8
1.2.7 Receiver....................................................................................... 8
1.2.8 Optical System ............................................................................. 9
1.2.9 Performance ................................................................................. 9
1.2.10 Environmenta l Con ditio ns............................................................. 9
2. INSTALLATION ...................................................................................................... 10
2.1 Unloading and unpacking........................................................................... 10
2.2 Foundation................................................................................................... 11
2.3 Assembling the Unit.................................................................................... 12
2.4 Using the Tilt Feature.................................................................................. 14
2.5 Cable Connections...................................................................................... 15
2.6 Grounding.................................................................................................... 16
2.7 Connection of Maintenance Terminal ........................................................ 17
3. START UP.............................................................................................................. 19
3.1 Start up procedure ...................................................................................... 19
3.1.1 Mobile operation aspects............................................................ 21
3.2 Verification of Proper Op eration ................................................................ 21
3.3 Settings for Normal Operation.................................................................... 22
3.4 Factory settings of user progra mmable p arameter s................................. 22
4. OPERATION........................................................................................................... 25
4.1 Operation Modes ......................................................................................... 25
4.2 Serial Lines. Open and Closed Port ........................................................... 25
4.3 User Commands .......................................................................................... 27
4.4 Data Messages ............................................................................................ 33
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4.4.1 Data Message No. 1 ...................................................................33
4.4.2 Data Message No. 2 ...................................................................36
4.4.3 Data Message No. 3 ...................................................................38
4.4.4 Data Message No. 4 ...................................................................39
4.4.5 Data Message No. 5 ...................................................................39
4.4.6 Data Message No. 6 ...................................................................39
4.4.7 Data Message No. 7 ...................................................................40
4.4.8 (Spare) .......................................................................................41
4.4.9 (Spare) .......................................................................................41
4.4.10 DMX611 operation ( optio n) .........................................................41
4.4.11 Status Message "S" .................................................................... 42
4.4.12 Manual Message .........................................................................45
4.5 Polling mode ................................................................................................45
4.6 Prevailing parameter settings .....................................................................46
4.7 Manual angle setting ...................................................................................47
5. FUNCTIONAL DESCRIPT ION ................................................................................49
5.1 Theory of Operation.....................................................................................49
5.2 Technical Description..................................................................................53
5.2.1 General .......................................................................................53
5.2.2 LIDAR Measurement ...................................................................55
5.2.3 Internal Monitorin g and Co ntrol...................................................58
5.3 Module Descriptions....................................................................................58
5.3.1 Optical Subassem bly CTB22.......................................................58
5.3.2 Laser Transmitter CT T 21............................................................59
5.3.3 Receiver CTR21 .........................................................................60
5.3.4 Optics Monitor CTL21 .................................................................61
5.3.5 Board Frame DMF51 ..................................................................62
5.3.6 Processor Board DMC50B ..........................................................63
5.3.7 DC Converter DPS52.................................................................. 67
5.3.8 Ceilometer Interface Board DCT 51 .............................................69
5.3.9 Line and Power Int erface S ubas sem bly CT P241 ........................70
5.3.10 Internal Heaters Subas sem bl y CT25039.....................................72
5.3.11 Tilt Angle Sensor CT3675 ...........................................................73
5.3.12 Window Conditioner CT 2614 / CT2688 .......................................74
5.3.13 Maintenance Term inal PSION 3 (Optio n) .....................................75
5.3.14 Modem DMX55 (Opti on) .............................................................76
5.3.15 Modem DMX50 (Opti on) .............................................................78
5.3.16 DMX611 ANet Interface (Option)..............................................80
5.4 Sky Condition Algorithm .............................................................................83
5.4.1 General.......................................................................................83
5.4.2 Option code ................................................................................83
5.4.3 Activation.................................................................................... 83
5.4.4 Algorithm overvie w......................................................................84
6. PERIODIC M AINTENANCE ....................................................................................87
6.1 Alarms and warnings...................................................................................87
6.2 Window Cleaning .........................................................................................87
6.3 Battery check ...............................................................................................88
6.4 Storage.........................................................................................................88
7. TROUBLESHOOTING ............................................................................................89
7.1 Normal Operation .........................................................................................89
7.1.1 Equipment ..................................................................................89
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Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
7.1.2 Instructions ................................................................................. 89
7.2 Troubleshooting.......................................................................................... 93
7.2.1 Warnings.................................................................................... 93
7.2.2 Alarms........................................................................................ 96
7.2.3 Miscellaneous............................................................................. 97
7.3 Failure Diagnosis ........................................................................................ 98
8. REPAIR.................................................................................................................. 99
8.1 General......................................................................................................... 99
8.2 Writing conventions used........................................................................... 99
8.3 Start-up procedure for replacem ent (all parts).........................................100
8.4 Transmitter CTT21......................................................................................101
8.4.1 Removal....................................................................................101
8.4.2 Replacement .............................................................................102
8.4.3 Compensation a djustm ents .......................................................105
8.5 Receiver CTR21 ..........................................................................................108
8.5.1 Removal....................................................................................108
8.5.2 Replacement .............................................................................109
8.5.3 Coaxial Cable Rep lacem ent ......................................................111
8.5.3.1 Removal....................................................................................111
8.5.3.2 Replacement .............................................................................112
8.6 Compensation Fiber...................................................................................113
8.6.1 Compensation Fi ber re placem ent..............................................113
8.7 Optics Monitor CTL21 ................................................................................114
8.7.1 Removal....................................................................................114
8.7.2 Replacement .............................................................................115
8.8 Boards of Board Fram e DM F51 .................................................................116
8.8.1 Removing boards ......................................................................116
8.8.2 Replacing boards ......................................................................117
8.8.2.1 Parameter settings of Ceilom eter I nterfac e bo ard DCT5 1 .......... 117
8.9 Line & Power Subassembly CTP241 .........................................................117
8.9.1 Removal....................................................................................117
8.9.2 Replacement .............................................................................119
8.9.3 Internal Heater S ubas sem bly CT25 03 9 Rep lacem ent ................ 120
8.9.4 Battery 4592 replac em ent instruc tions.......................................121
INDEX.......................................................................................................................... ... 123
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Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
LIST OF FIGURES
Figure 1-1 Ceilometer CT25K ..........................................................................................1
Figure 1-2 Data Line Connection Options......................................................................... 5
Figure 2-1 Measurement Unit Handle.............................................................................10
Figure 2-2 Foundation Construction ...............................................................................11
Figure 2-3 Mounting the Pedestal ................................................................................... 12
Figure 2-4 Attaching the Measurement Unit and the Shield............................................13
Figure 2-5 External Connectors (bottom view) ...............................................................15
Figure 2-6 Termination Box Wire Connections .............................................................. 16
Figure 3-1 CT25K Switches and LEDs...........................................................................20
Figure 4-1 Operation Modes........................................................................................... 25
Figure 4-2 Open and closed port.....................................................................................26
Figure 5-1 Typical Measurement Signal .........................................................................49
Figure 5-2 Measurement Unit Components .....................................................................53
Figure 5-3 Subassembly Interconnections.......................................................................54
Figure 5-4 Block Diagram of Operational Units ............................................................. 56
Figure 5-5 Optical Subassembly CTB22 with Optics Monitor, Transmitter and Receiver
Subassemblies ............................................................................................... 58
Figure 5-6 CTT21 Block Diagram ..................................................................................59
Figure 5-7 CTR21 Block Diagram..................................................................................60
Figure 5-8 CTL21 Block Diagram ..................................................................................61
Figure 5-9 DMF51 Frame...............................................................................................62
Figure 5-10 DMC50B Block Diagram ............................................................................63
Figure 5-11 DIP Switch Settings of the DMC50............................................................. 66
Figure 5-12 DPS52 Block Diagram................................................................................. 67
Figure 5-13 DCT51 Block Diagram................................................................................69
Figure 5-14 CTP241 Wiring ...........................................................................................71
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Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
Figure 5-15 CT25039 Wiring Diagram .......................................................................... 72
Figure 5-16 CT3675 Tilt Angle Sensor.......................................................................... 73
Figure 5-17 Window Conditioner CT2614/CT2688 ....................................................... 74
Figure 5-18 RS Cable..................................................................................................... 75
Figure 5-19 DMX55 Block Diagram.............................................................................. 76
Figure 5-20 DMX50 Block Diagram.............................................................................. 78
Figure 5-21 DMX611 Block Diagram............................................................................ 80
Figure 8-1 Board Connectors of the DMF51 Board Frame............................................101
Figure 8-2 Removing the Laser Transmitter..................................................................102
Figure 8-3 Adjusting the compensation.........................................................................106
Figure 8-4 Adjusting the compensation.........................................................................107
Figure 8-5 Removing the Receiver ................................................................................ 109
Figure 8-6 Removing the Optics Monitor ......................................................................115
Figure 8-7 Boards of the DMF51 Board Frame.............................................................116
Figure 8-8 Removing Line and Power Interface Subassembl y CTP241 .........................119
Figure 8-9 Internal heater replacement..........................................................................121
Figure 8-10 Battery replacement...................................................................................122
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Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
INTRODUCTION TO MANUAL
The purpose of this User’s Guide is to be a general information source as well
as a detailed operational guide for the user of Ceilometer CT25K.
This document is divided into 8 chapters. Chapter 1 offers an overview and
technical specifications of the CT25K Ceilometer. The following chapters 2
and 3 contain installation and start up instructions. Operational instructions
with user commands and data messa ges are included in chapter 4. Chapter 5
includes functional description of the Ceilometer and chapters 6, 7 and 8
instructions for maintenance, troubleshooting and repair.
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Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
VALIDITY OF THIS M ANUAL
This manual covers ceilometer CT25K in all its configurations as defined by
the parts and options listed in section 1.1, running under software re vision
CT25K- 2.01 or 2.01a
Table 1-1 lists the revision history that may apply in comparison to other units
in use:
Software revision s Description
CT25K-1.01 First Release
CT25K-1.02 Intermediate release (not in us e)
CT25K-1.03 Intermediate release (not in us e)
CT25K-1.04 Production rev. 95-05-15...97-02-03
CT25K-1.04h Special rev. with Qualimetrics and
DR21 messages
CT25K-1.05 Production rev. 97-02-03...
CT25K-2.00 Production rev. 97-11-01...
CT25K-2.01 Production rev. 98-03-17...
CT25K-2.01a Production r ev. 99-02-09…
Table 1-1 Software Revisions
Table 1-2 lists the hardware history that may apply in comparison to other
units in use:
Hardware history Description
CT25K model A First Release
CT25K model B Enclosur e CT1669 replaced with CT15035.
Model A pedestal CT2665 (Fiberglass) is option
New Metal Pedestal CT25106 is standard.
Line and Power Interface Subassembly CTP21
changed to CTP241.
Internal Heaters Subassembl y CT2690 replaced
with CT25039.
CTB22 Replaces CTB21 since 97-05-26
DMC50B Replaces DMC50A since 97-11-05
DPS52 Replaces DPS51
Table 1-2 Hardware Hi sto ry
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Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
SAFETY SUMMARY
The following safety precautions must be observed during all phases of
operation, service, and repair of this instrument. Failure to compl y with these
precautions or with specific wa rnings elsewhere in this manual violat es safety
standards of design, manufacture, and intended use of the instrument.
VAISALA assumes no liability for the customer’s failure to comply with these
requirements.
LASER SAFETY
The CT25K is officially certified as a Class 1 laser device in accordance with
European standard EN 60 825-1:1994. It is also classified in accordance w ith
U.S. regulation 21 CFR 1040 as a Class 1 laser device. This means that a
CT25K Ceilometer installed in a field environment with instrument covers on
and pointed vertically or near-vertically poses no established biological
hazard to humans.
The device is equipped with the following label:
The instrument is intended for operation in an area restricted from public
access, and to be pointed vertically or near-vertically up. The following
precautions are to be noted and followed during service and maintenance of
the instrument:
• Never look directly into the Laser Transmitter with magnifying optics
(glasses, binoculars, telescopes, etc.)
• When operating, avoid looking at the ceilometer unit from the beam
direction. When tilting the unit, make sure that it is not being viewed from
the beam direction with magnifying optics.
• Only trained personnel should perform maintenance fun ctions. Work area
access by unauthorized persons during service operations must be
prevented.
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Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
GROUND THE INSTRUMENT
To minimize shock hazard, the instrument chassis and cabinet must be
connected to an electrical ground. The instrument is equipped with a
three-conductor AC power connector. The power cable must either be
plugged into an approved three-contact electrical outlet or the instrument must
be carefully earthed to a low-resistance sa fet y ground.
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE
Do not operate the instrument in the presence of flammable gases or fumes.
Operation of any electrical instrument in such an environment constitutes a
definite safety hazard.
DO NOT SERVICE OR ADJUST ALONE
Do not attempt internal service or adjustment unless anothe r person, capable
of rendering first aid and resuscitation, is pres ent.
DO NOT SUBSTITUTE PARTS OR MODIFY INSTRUMENT
Because of the danger of introducing additional hazards, do not install
substitute parts or perform any unauthorized modification to the instrument.
Return the instrument to a VAISALA office or authorized Depot for service
and repair to ensure that safety features are maintained.
KEEP AWAY FROM LIVE CIRCUITS
Operating personnel must not remove instrument covers. Component
replacement and internal adjustments must be made by qualified maintenance
personnel. Do not replace components with power cable connected. Under
certain conditions, dangerous voltages may exist even with the power cable
removed. To avoid injuries, always disconnect powe r and discharge circuits
before touching them.
High voltage will be readily accessible when the transmitter (CTT21) or
receiver (CTR21) covers are removed and they are connected to a powered
unit. High voltage is present in the Line and Power Interface Subassembly
(CTP241), the Internal Heaters subassembly, the Frame (DMF51) Mother
Board, and the Window Conditioners at the top of the Shield.
Transmitter (CTT21), Receiver (CTR21), and Line and Power Input
Subassembly (CTP241) have the following warning label:
WARNING! +,*+9 2/7$*(, 16,' (7+,6( 1&/26 85(
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Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
Internal Heaters Subassembly can be hot and has the following warning
labels:
DANGEROUS PROCEDURE WARNINGS
Warnings, such as the example below, precede potentially dangerous
procedures throughout this manual. Instructions contained in the warnings
must be followed:
WARNING
Dangerous voltages, capable of causin g death, are present
in this instrument. Use extreme caution when handling,
testing, and adjusting.
CAUTION
The equipment contains parts and assemblies sensitive to
damage by Electrostatic Discharge (ESD). Use ESD
precautionary procedures when touching, removing or
inserting.
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Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
1. GENERAL INFORMATION
1.1 Product Overview
Ceilometer CT25K measures cloud heights and vertical visibilities. The small
and lightweight measurement unit suits well for mobile operation.
The CT25K Ceilometer employs pulsed diode laser LIDAR technology
(LIDAR = Light detection and ranging), where short, powerful laser pulses
are sent out in a vertical or near-vertical direction. The reflection of light backscatter - caused by haze, fog, mist, virga, precipitation and clouds is
measured as the laser pulses traverse the sky. The resulting backscatter
profile, i.e. signal strength versus height, is stored and processed and the
cloud bases are detected. Knowing the speed of light, the time dela y between
the launch of the laser pulse and the detection of the backscatter signal
indicates the cloud base height.
The CT25K is able to detect three cloud layers simultaneously. Besides cloud
layers it detects whether there is precipitation or other obstructions to vision.
No adjustments in the field are needed. The embedded software includes
several service and maintenance functions and gives continuous status
information from internal monitoring. The software is designed to give the
full backscatter profil e.
SHIELD
MEASUREMENT UNIT
PEDESTAL
9412-026
Figure 1-1 Ceilometer CT25K
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Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
Ceilometer CT25K consists of three main parts (Figure 1-1):
1. Measurement Unit including
- Optical Subassembly CTB22
- Laser transmitter CTT21
- Receiver CTR21
- Optics Monitor CTL21
- Frame DMF51 including
- Processor Board DMC50B
- DC Converter DPS52
- Ceilometer Interface Board DCT51
- Modem (optional)
- Line and Power Interface Subassembl y CTP241
- No-Break Battery
- Internal Heaters Subassembly CT25039
- Tilt Angle Sensor CT3675
- Internal Cables etc.
2. Shield including
- Built-in Window Conditioner CT2614/CT2688 (warm air blower)
options - 220...240 VAC (CT2614)
- 100...115 VAC (CT2688)
3. Pedestal
- Metal pedestal CT25106 is standard. For off-shore applications it is
recommended to use fiberglass pedestal CT26 65.
The complete delivery also includes mating cables with connectors for power
and communication, installation hardware, an Allen key, a triangle ke y for the
Measurement Unit door and this CT25K User’s Guide.
In addition, the following options may be included in the delivery:
- Maintenance Terminal (Palmtop compute r) PS ION3
- connected to Measurement Unit at the external conn ector J4 via RS232 interface
- Termination Boxes (2) for Line Power CT3709 (external connector J2)
and Communication Cable CT3707 (external connecto r J 3) connections
- Tropics Window CT35043 on Measurement Unit instead of Standard
Window to protect the laser from direct sun radiation.
- Optical Termination Hood CT25184 for indoor service us e
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Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
- Shock Absorber CT35022 for ship installations
- PC Terminal cable CT35198 to connect the connector of the RS-232 p ort
of the PC to the maintenance port
1.2 Specifications
1.2.1 Mechanical
Dimensions:
Measurement unit 760 x 280 x 245 mm
(30 x 11 x 10 in.)
Height with shield and pedestal 1320 mm (52 in.)
Weight:
Measurement unit 17 kg (37 lb.)
Shield 10 kg (22 lb.)
Metal pedestal 8 kg (17 lb.)
Fiberglass pedestal (option) 13 kg (28 lb.)
Cardboard transport container size 1170 x 740 x 430 mm (46 x 29 x 17 in.)
Cardboard transport container weight 51 kg (111 lb.)
Plywood transport container size 1240 x 760 x 450 mm (49 x 30 x 18 in.)
Plywood transport container weight 70 kg (152 lb.)
1.2.2 External Connector J1 - Window conditioner
Connector J1: Type Binder series 693, 09-4228-00-07
(female)
Mating connector type: Type Binder series 693, 99-4225-70-07
7-pin (male) elbow
1.2.3 External Connector J2 - Power input
At nominal line voltage 115 V or 230 V
Power consumption (typical)
Total 365 W
Measurement unit 15 W
Internal heater 120 W
Window conditioner heater 200 W
Window blower 30 W
Frequency 45-65 Hz
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Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
Power connector (J2): Type Binder series 693, 09-4223-00-04
4-pin (male)
Mating connector type: Type Binder series 693, 99-4222-70-04
(female) elbow
No-break power supply 12V Sealed Lead Acid Battery, 2 Ah
Overvoltage Protection Low-press filter , VDR
1.2.4 Output Interface
The data port can operate according to the following serial line standards :
RS-232
RS-422
RS-485, multidrop, 2-wire / 4-wire
The data port can also be operated through DMX55 and DMX50 modems or
ANet Bus interface DMX611.
The maintenance port is an RS-232 serial line, ex cept when the data line is set
to RS-422 or RS-485; then the maintenance line voltage levels become 0 and
+5 V.
1.2.4.1 External Connector J3 - Data line
The data line is intended to be used for measurement data communi cation, but
it can also be used with Ceilometer Maintenance Terminal, PC or other
terminals.
Connector (J3): Type Binder series 693, 09-4227-00-07
7-pin (male)
Mating connector type: Type Binder series 693, 99-4226-70-07
(female) elbow
Baud Rate: 2400 baud standard with RS-232
300, 4800 and 9600 baud available
300 bit/s with modem DMX55
2400 bit/s standard with modem DMX50
300, 1200, 2400 bit/s available
Data compression allows up to 9600 bit/s
throughput
Max. Distance to Operate: 300m (1000 ft) with RS-232,
4
1.2 km (4000 ft) with RS-422 and RS-485,
all at 2400 baud with typical communication
cables
16 km (10 mi) with Modem
Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
Standard Character F rame: 1 Start Bit
7 Data Bits
Even Parity
1 Stop Bit
Standard Character Code: USASC II
Pin Connections 1 RD- / AN2Lo
2 Modem Lead A / RxD / RD+ / AN1Hi
3 Modem Lead B / TxD / SD+ / AN1Lo
4 Signal Ground
5 SD- / AN2Hi
6 +12 V DC supply (200 mA max for 1
hour, 100 mA continuous, for external
equipment)
Modem circuits are non-polar and symmetrical. All modem circuits are
electrically floating to overvoltage protection ratin g (300V-500 V).
Overvoltage Protection in each circuit:
Primary Noble Gas Surge Arrester
Secondary VDRs, Transient Zener Diodes
or normal Diodes
Figure 1-2 Data Line Connection Options
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User’s Guide CT25K-U059en-2.1
1.2.4.2 External Connector J4 - Maintenance line
Maintenance line is intended for on-site maintenance and can be used with
Ceilometer Maintenance Terminal, PC or other terminal.
Connector (J3): Type Binder series 693, 09-4224-06-04
4-pin (male)
Mating connector type: Type Binder series 693, 99-4221-70-04
(female) elbow
Baud Rate: 2400 baud standard and default
300, 4800, 9600 baud available
Distance to Operate: 300 m (1000 ft) at 2400 baud with typical
communication cables
Standard Character F rame: 1 Start Bit
7 Data Bits
Even Parity
1 Stop Bit
Standard Character Code: USASC II
Pin Connections 1 RxD / RD+ (0...5 V)
2 TxD / SD+ (0...5 V)
3 +12 V DC supply from internal battery
(100 mA continuous, 200 mA max.)
4 Signal Ground / Equipment Ground
Overvoltage Protection in each circuit:
Primary Noble Gas Surge Arrester
Secondary VDRs, Transient Zener Diodes or
normal Diodes
1.2.5 Modem Options
1.2.5.1 Modem board DMX55
ITU-T V.21 / Bell 103 full duplex modem interface for serial asynchronous
data interchange
Data Rate: 300 bit/s
Modulation method: FSK
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Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
Answer Mode Standard Frequencies:
V.21 Bell 103
Mark (1) 1650 Hz 2225 Hz
Space (0) 1850 Hz 2025 Hz
Originate Mode Optional
Signal Level: -10 dBm (0.3 V) into 600 Ohm standard
(Jumper selectable)
Max. Distance to Operate 0...16 km (0...10 miles)
with 22 AWG (0.35 mm2) unshielded
twisted pair
The signal circuit is electrically floating to overvoltage protection rating
(300V-500V).
1.2.5.2 Modem board DMX50
Processor: Intel 80C32 custom version
Modem: Signal Processor Chip Silicon Systems SSI
73K224L
Modem standards supported: V.21/ V.22/ V.22bis and Bell 103, Bell 212
Modulation method: 300 FSK/ 1200 DPSK/ 2400 QAM
Compression & error correction: V. 42, V.42bis and MNP 2-5
Adaptive equalization for optimum performance over all lines.
1.2.5.3 ANet Interface DMX611
The DMX611 serves as an interface between the CT25K and Vaisala
proprietary ANet and INet busses.
Baud Rate 2400
Signal Level 0 dBm
Max. Distance to Operate 0…5 km multi-drop network
Standard Character Frame 8 Bit synchronous
Character Code Binary
iNet protocol Packet format.
Twisted pair 22 AWG
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Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
1.2.6 Transmitter
Laser Source: Indium Gallium Arsenide (InGaAs) Diode
Laser
Center Wavelength: 905 ± 5 nm at 25 °C (77 °F)
Operating Mode: Pulsed
Nominal Pulse Properties at Full R ange Measu rem ent:
Energy: 1.6 µWs ± 20% (factory adjustment)
Peak Power: 16 W typical
Width, 50%: 100 ns typical
Repetition Rate: 5.57 kHz
Average Power: 8.9 mW (full range measurement)
Max Irradiance: 170 µW/cm ² measured wit h 7 mm aperture
Laser Classification: Officially certified as Class 1 laser device in
accordance with EN 60 825-1:1994
Class 1 in compliance with FDA CFR
1040.10 (Subsection e,3)
Laser Source Geometry: Five-stack, 0.4 mm (16 mil) square
Beam Divergence: ± 0.53 mrad edge, ± 0.75 mrad diagonal
1.2.7 Receiver
Detector: Silicon Avalanche Photodiode (APD)
Responsivity at 905 nm: 65 A/W
(factory adjustment)
Surface Diameter: 0.5 mm (0.02 in.)
Interference Filter: Center wavelength 908 nm typical
50% Pass Band: 35 nm at 890-925 nm typical
Transmissivity at 905 nm: 80 % typical, 70 % minimum
Field-of-View Divergence: ± 0.66 mrad
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Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
1.2.8 Optical System
Optics System Focal Length: 377 mm (14.8 in.)
Effective Lens Diameter: 145 mm (5.7 in.)
Lens Transmittance: 96 % typical
Window Transmittance: 98 % typical, clean
1.2.9 Performance
Measurement Range: 0...25,000 ft. (0...7.5 km)
Resolution: 50 ft
25,000 ft. Acquisition Time: min. 15 s
max. 120 s
Receiver Bandwidth: 3 MHz (-3db)
1.2.10 Environmental Conditions
Ambient Temperature: -50...+60 °C (-60 ...+140 °F)
Humidity: to 100 %RH
Wind: to 100 kt (50 m/s)
Vibration: 0.5 g 5 - 500 Hz
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Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
2. INSTALLATION
NOTE
Before the installation, make sure that the CT25K
configuration, especially line voltage setting, is in
compliance with local circumstances. Information about
the CT25K configuration in question is included in the
delivery.
2.1 Unloading and unpacking
The CT25K is shipped in one container containing the Measurement Unit,
Shield and Pedestal, and all equipment, accessories an d docum entation ne eded
for carrying out the installation. Store the original packagin g for possible later
transport need.
For opening, the package is t o be placed on a flat surface with t he indicated
top side up. The container is opened from the top side and the ceilometer
including all other parts are carefull y removed.
• Use proper gloves for protection against sharp edges, et c.
• Avoid touching the window or lens surfaces unless cleaning according to
instructions.
• Maintain the integral protective caps on the unus ed external connectors (J3
Data line or J4 Maintenance line).
• Use the measurement unit handle fo r lifting and carr ying (Figure 2-1).
If mishandling occurs during transit or installation, the instrument should be
returned to a VAISALA office or authorized Depot for insp ection.
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Figure 2-1 Measurement Unit Handle
Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
2.2 Foundation
The standard foundation for the CT25K ground installation is a concrete
foundation. The minimum dimensions suggested are present ed in Figure 2-2.
Mounting hardware is included with the delivery.
There are two alternative ways to make a foundation: to cast a new or to use
an existing foundation.
- If a new foundation is laid, the M10x40 Wedge Bolts and Foundation
Screws (4 each), are suggested to be cast into the concrete so that
approx. 30 mm (1.25 in.) of the foundation screw threads stand above
the surface.
- If an existing foundation is used, four holes of diameter 12 mm and
depth 165 mm (0.5 x 6.5 in.) are drilled into the concrete. The Wedge
Bolt and Foundation Screw combinations are placed in the holes, with
Wedge Bolts down; the protruding threads are alternately hammered
and tightened a few times so that the Wedge Bolts attach to the hole
walls.
In case the CT25K replaces a CT12K Ceilometer, the ex isting foundation and
screws can be used.
Figure 2-2 Foundation Construction
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Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
If the tilt feature will be used (see section 2.4), observe this in the la yout of
the foundation screws and pedestal placement.
2.3 Assembling the Unit
The CT25K Ceilometer is assembled in four stages:
1. Mount the pedestal on the foundation.
2. Attach the measurement unit to the pedestal.
3. Mount the shield on the measurement unit.
4. Connect the external cabl es.
1. Place the Pedestal on the foundation (or equivalent installation place) so
that the vertical leg of the pedestal faces East in the Northern hemisphere,
and West in the Southern hemisphere.
If the tilt feature will be used (see section 2.4.), observe this in the layout of
the foundation screws and pedestal placement. Place the flat washers on the
foundation screws and fix the nuts (Figure 2-3).
2. Start mounting the measurement unit by rotating the friction ring of the
flange to the position shown in Figure 2-4 (the screw h oles horizontally).
Remove the Allen head screws (2 pcs) and flat w ashers.
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Figure 2-3 Mounting the Pedestal
Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
Place the measurement unit on the pedestal flange. Attac h the pedestal flange
to the measurement unit by the two Allen head screws with flat washers. An
Allen key is included in the delivery.
Figure 2-4 Attaching the Measurement Unit and the Shield
3. Before placing the shield pull the knobs (pidgeon blue) on the shield
outwards. Place the shield carefully on the Measurement Unit; be careful
with the Window Conditioner cable. Tighten the two attachment knobs
(Figure 2-4).
Before connecting the Window Conditioner cable check that the voltage
rating of the Window Conditioner (written at its connector) is correct.
Connect the Window Conditioner cable plug of the shield to the
measurement unit external connector J1 .
Connect external cables according to section 2. 5.
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Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
2.4 Using the Tilt Feature
The Measurement Unit and Pedestal of Ceilometer CT25K are designed so
that the unit can operate in a tilted direction. The built-in tilt angle sensor
CT3675 detects the tilt angle, i.e. deviation from the vertical. The tilt angle
ranges from -15 to +90 degrees from vertical; the angle is positive when the
measurement unit door turns towards the ground. The cosine of the tilt angle
is used for automatic correction of the detected cloud base height, which
enables accurate cloud base measurements also in a tilted direction.
Several advantages can be realized with the aid of this feature:
• Heavy weather conditions
Using a slight tilt angle for instance 15 degrees, the measurement unit
window is kept better protected from precipitation, thus enhancing the
availability of correct measurements in heavy weather conditions.
• Aircraft approaches
The beam can be directed towards a direction, which better r epresents the
approach of an aircraft than th e straight vertical. Useful e.g. for helicopter
approaches, and sites where the ceilometer cannot be located exactl y at the
desired spot.
• Hard target and testing purposes
Tilting the unit down by 90 degrees permits verification of operation
against a hard target at a known distance. Useful in connection with
installation and maintenance. Enables real backscatter signal detection
when there are no clouds in the sky.
WARNING
Make sure that nobody is viewing the unit from th e beam
direction with magnifying optics!
• Maintenance
By tilting the unit back -15 degrees, better access is gained to the interior
during maintenance.
• In the tropics
Between the latitudes of ± 25 degrees, where the sun can be straight above
the unit, a slight tilting prevents the laser from direct sun radiation, which
would otherwise destroy the laser. The other alternative is to use a tropics
window on the measurement unit instead of a stand ard window.
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Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
As these advantages are partly contradictory and cannot or need not all be
realized, the user must decide the final installation direction. In doing so, the
following must be observed:
NOTE
Unless a tropics window is used, the unit must never be
directed so that the sun shines directly into the optics,
because the lens will focus all radiation into a very hot
spot.
2.5 Cable Connections
All external connectors to the Measurement Unit are located at th e bottom left
edge as seen from the door direction. Figure 2-5 shows the external
connectors J1, J2, J3 and J4.
• The Window Conditioner (warm air blower) mounted in the Shield is
permanently connected to J 1.
• Line Power input is connected to J2.
Figure 2-5 External Connectors (bottom view)
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Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
• Remote communication is normally connected to J3.
• A local maintenance terminal, for example PSION3, is intended to be
connected to J4. A protective cap is included for covering J4 when not in
use.
External mating connectors with 2 m (7 ft.) cable are included for J2 and for
J3. The power plug of the J2 cable can be cut when the unit is permanentl y
installed at the final site.
The cables for J2 and J3 are intended to be drawn through the hole of the
pedestal to the connectors. Provide sufficient slack for permitting the unit to
be tilted later.
Figure 2-6 shows the connecting signal leads with optional Powe r and Signal
Termination Boxes.
Figure 2-6 Termination Box Wire Connections
Suggested wire dimensions for the external cablin g are:
Line Power Supply: 3 x 1.5 mm2 (AWG 16)
Remote Communication: 0.35 mm2 (AWG 22) twisted pair with shield
When permanent line power installation is made, the
maximum size of the fuse protecting the power line is 10 A
2.6 Grounding
The power supply connector J2 provides a standard protective ground for the
instrument chassis.
16
NOTE
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