Vaisala FD12P - Page 6

User's Guide _______________________________________________________________________
6
______________________________________________________ M210296en-A
Optical Arrangement ........................................................... 96
FDT12B Transmitter Unit .................................................... 96
FDR12 Receiver Unit .......................................................... 98
Additional Measurements ..................................................... 99
General ............................................................................... 99
DRI21 Interface Board ........................................................ 99
DRD12 Rain Detector ....................................................... 100
DTS14B Temperature Sensor .......................................... 101
FDP12 Control Unit .............................................................. 101
Measurement Signal Processing........................................ 103
Optical Signal Processing................................................. 103
DRD12 Signal Processing ................................................ 104
Algorithm Description ......................................................... 105
Visibility ............................................................................. 105
Detecting Precipitation ...................................................... 106
Precipitation Intensity........................................................ 106
Precipitation Accumulation ............................................... 107
Present Weather ............................................................... 108
Precipitation Types ...................................................... 108
Liquid Precipitation ................................................. 109
Frozen Precipitation................................................ 110
Mixed Precipitation ................................................. 111
Unknown Precipitation............................................ 111
Visibility Types ............................................................. 111
Fog.......................................................................... 111
Haze and Mist......................................................... 112
Weather Classes ......................................................... 112
Weather Code Selection.............................................. 113
Applications.......................................................................... 113
Internal Monitoring .............................................................. 114
Built-in Tests ..................................................................... 114
Memory Tests ................................................................... 115
Signal Monitoring .............................................................. 115
Hardware Monitoring......................................................... 115
Contamination Monitoring................................................. 116
CHAPTER 6
MAINTENANCE ......................................................................................... 117
General.................................................................................. 117
Cleaning ................................................................................ 118
Cleaning Lenses and Hoods............................................. 118
Cleaning DRD12 Rain Detector........................................ 118
Calibration ............................................................................ 119
General ............................................................................. 119
Visibility Calibration........................................................... 119
Calibration Check Procedure....................................... 120
Calibration Procedure .................................................. 123
Calibrating the DTS14B Temperature Sensor............. 124
Removing and Replacing.................................................. 126
Removing and Replacing Optical Units ....................... 126
Removing and Replacing the DRD12 Rain Detector .. 129