Vaisala FD12P User's Guide download pdf (Page 104)

User's Guide _______________________________________________________________________

104

_____________________________________________________ M210296en-A

9807-034

Figure 28 Optical Signal Amplitude Distribution (in Rain)

DRD12 Signal Processing

The DRD12 output voltage is measured once a second by the DRI21

interface board. With dry surfaces, the voltage is approximately 3 V

and drops when the sensing elements become wet (Figure 29 below).

0110-186

Figure 29 DRD12 Surface Signal (Heavy Rain Beginning)

1 2 ... 99 100 101 102 103 104 105 106 107 108 109 ... 153 154

USER'S GUIDE 1
Table of Contents 3
CHAPTER 4 4
CHAPTER 5 5
CHAPTER 6 6
List of Figures 7
List of Tables 8
GENERAL INFORMATION 11
Version Information 12
Related Manuals 12
General Safety Considerations 12
ESD Protection 15
Trademarks 16
Warranty 16
PRODUCT OVERVIEW 17
0201-085 18
Sensing Elements 19
Electronics Enclosure 20
Structural Elements 20
Operating Principle 21
Using FD12P 22
Equipment Nomenclature 23
Specifications 24
Mechanical Specifications 24
Electrical Specifications 24
Optical Specifications 25
Capabilities and Limitations 26
Visibility Measurement 26
Environmental Specifications 27
INSTALLATION 29
Location and Orientation 30
0110-178 31
Equipment Grounding 32
0111-001 33
Internal Grounding 34
Grounding Remote Units and 34
Communication Cable 34
Cable Selection 35
Line Power Cabling 35
Unloading and Unpacking 36
Unpacking Procedure 36
Storage Information 36
Installation Procedures 37
Constructing the Foundation 37
Mounting When Casting the Pad 38
0110-180 39
Assembling the FD12P 40
Sensor to the Mast 41
0201-088 42
Connecting Cables 43
9509-011 44
0110-183 45
0110-184 46
0205-006 47
Day/Night Switch to FD12P 48
Luminance Meter 49
Communication Options 50
9509-013 51
Modem DMX21 52
Originate Mode Answer Mode 53
TXD 0 1 0 1 53
CCITT 1180 980 1850 1650 53
Analog Transmission 55
Startup Testing 56
Initial Settings 56
OPERATION 59
Markings Used in This Manual 61
OPEN Command 61
CLOSE Command 62
Automatic Message Sending 62
Message Types 63
Message 0 64
Message 1 64
Message 2 65
Message 3 65
Message 4 66
Messages 5 and 6 66
Message 7 68
Message Polling 69
FD12P Command Set 70
HELP Command 70
MES Command 71
AMES 1 60 ↵ 72
AMES 0 0 ↵ 72
Weather Related Commands 73
PRW Command 77
CLRS Command 78
WHIS Command 78
System Configuration Commands 79
CONF Command 80
CONF. PASSWORD (4 CHARS MAX) 81
ANALOG OUTPUT RANGE 83
MAX VISIBILITY ( 10000) 83
MIN VISIBILITY ( 50) 83
END OF CONFIGURATION 83
BAUD Command 84
BLSC Command 84
Maintenance Commands 85
CAL Command 87
TCAL Command 87
CLEAN Command 88
CHEC Command 89
FREQ Command 89
DRY and WET Commands 89
AN Command 90
Analog Output Commands 91
Data Scaling 92
Hardware Check 92
Other Commands 93
RESET Command 94
FUNCTIONAL DESCRIPTION 95
Optical Measurement 96
Optical Arrangement 96
FDT12B Transmitter Unit 96
9611-002 97
FDR12 Receiver Unit 98
Additional Measurements 99
DRD12 Rain Detector 100
DTS14B Temperature Sensor 101
FDP12 Control Unit 101
9611-004 102
Measurement Signal Processing 103
Optical Signal Processing 103
DRD12 Signal Processing 104
Visibility 105
Algorithm Description 105
Detecting Precipitation 106
Precipitation Intensity 106
Precipitation Accumulation 107
Present Weather 108
0201-092 109
Visibility Types 111
Weather Classes 112
Applications 113
Internal Monitoring 114
Built-in Tests 114
Memory Tests 115
Signal Monitoring 115
Hardware Monitoring 115
Contamination Monitoring 116
MAINTENANCE 117
Cleaning 118
Cleaning Lenses and Hoods 118
Cleaning DRD12 Rain Detector 118
Calibration 119
Visibility Calibration 119
Calibration Check Procedure 120
0201-087 122
Calibration Procedure 123
1 = Sensor holder 125
3 = Fixing screw 125
Removing and Replacing 126
0110-187 127
0110-189 129
Replacement 130
TROUBLESHOOTING 133
Message Missing 134
Visibility Value is Missing 135
There Is None 136
FD12P Reports Frozen 136
Precipitation during Rain 136
Have Jumper Settings Been 137
Changed? 137
Getting Help 140
Return Instructions 140
NWS AND WMO CODES USED IN 143
JUMPER SETTINGS AND INTERNAL 147
CPU Board 149
DC-Regulator 149
DRI21 Interface Board 149
TRANSMITTER AND RECEIVER TEST 151
Table 42 Receiver Test Points 152

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Vaisala FD12P User's Guide Page 104

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