User's Guide ______________________________________________________________________
4 ___________________________________________________________________ M210482EN-B
User Commands .....................................................................39
Data Messages........................................................................44
CL31 Data Messages No. 1 and 2 ......................................45
CRC16 Checksum..........................................................51
CL31 Status Message .........................................................52
CT12K Messages................................................................55
CT12K Digital Message No. 2........................................55
CT12K Digital Message No. 3........................................59
CT25K Data Messages .......................................................60
CT25K Data Message No. 1 ..........................................60
CT25K Data Message No. 6 ..........................................62
CT25KAM Data Messages..................................................64
LD40 Standard Telegram ....................................................64
Telegram Structure Remarks .........................................66
Failure and Warning Messages .....................................66
Checksum Calculation....................................................69
Manual Message .................................................................70
Polling Mode ...........................................................................70
CHAPTER 5
FUNCTIONAL DESCRIPTION .....................................................................73
Theory of Operation ...............................................................73
Basic Principle of Operation ................................................73
Practical Measurement Signal.............................................74
Noise Cancellation ..............................................................74
Return Signal Strength ........................................................75
Height Normalization ...........................................................75
Backscatter Coefficient........................................................75
Extinction Normalization and Vertical Visibility....................77
CHAPTER 6
Periodic Maintenance.............................................................79
Alarms and Warnings ..........................................................79
Window Cleaning.................................................................80
Calibration ......................................................................80
Checking the Door Gasket ..................................................81
Battery Check ......................................................................81
Storage ................................................................................82
CHAPTER 7
TROUBLESHOOTING..................................................................................83
Accessing the Diagnostic Information.................................84
Warning and Alarm Messages ..............................................86
Technical Support ..................................................................90
Vaisala Service Centers .........................................................90