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VAISALA________________________________________________________________________ 5 
List of Tables 
Table 1  Manual Revisions.......................................................................7 
Table 2  Related Manuals ........................................................................7 
Table 3  Specifications for the Grounding Terms...................................11 
Table 4  Vaisala Ceilometer CL31 Main Parts .......................................19 
Table 5  Vaisala Ceilometer CL31 Optional Parts.................................. 19 
Table 6  Factory Defaults of User-Programmable Parameters..............42 
Table 7  Sky Cover Values from the Sky Condition Algorithm...............50 
Table 8  User Level Commands.............................................................58 
Table 9  Advanced Level Commands ....................................................60 
Table 10  Messages with 10 m Resolution (Standard Mode) ..................63 
Table 11  Messages with 5 m Resolution (High Resolution) ...................64 
Table 12  Error Group Definition ..............................................................85 
Table 13  Error Group 1 (Byte 83)............................................................85 
Table 14  Error Group 2 (Byte 84)............................................................85 
Table 15  Error Group 3 (Byte 85)............................................................85 
Table 16  Error Group 4 (Byte 86)............................................................86 
Table 17  Error Group 5 (Byte 87)............................................................86 
Table 18  Error Group 6 (Byte 88)............................................................86 
Table 19  Error Group 7 (Byte 89)............................................................86 
Table 20  Command Telegram Description 'Polling Request'..................90 
Table 21  CL31 Status, Warnings ............................................................99 
Table 22  CL31 Status, Alarms ..............................................................100 
Table 23  CL31 Status, Miscellaneous Problems ..................................101 
Table 24  Available Spare Parts.............................................................103 
Table 25  Ceilometer CL31 Mechanical Specifications.......................... 127 
Table 26  Window Blower.......................................................................127 
Table 27  Power Input ............................................................................128 
Table 28  Data Line................................................................................129 
Table 29  Maintenance Line...................................................................130 
Table 30  Modem Module DMX501 Specifications ................................131 
Table 31  Transmitter Specifications...................................................... 131 
Table 32  Receiver Specifications..........................................................131 
Table 33  Optical System Specifications................................................132 
Table 34  Performance Specifications....................................................132 
Table 35  Environmental Conditions Specifications...............................132