SRS Sensors
CONTENTS
Contents
1
Introduction
1
1.1
Customer Support . . . . . . . . . . . . . . . . . . . .
1
1.2
About This Manual
. . . . . . . . . . . . . . . . . . .
2
1.3
Warranty . . . . . . . . . . . . . . . . . . . . . . . . .
2
1.4
Seller’s Liability . . . . . . . . . . . . . . . . . . . . . .
2
2
About SRS
3
2.1
Overview
. . . . . . . . . . . . . . . . . . . . . . . . .
3
2.2
Specifications . . . . . . . . . . . . . . . . . . . . . . .
4
3
Theory
6
3.1
Normalized Difference Vegetation Index (NDVI)
. . .
6
3.2
Estimating LAI . . . . . . . . . . . . . . . . . . . . . .
8
3.3
Fractional Interception of Photosynthetically Active
Radiation . . . . . . . . . . . . . . . . . . . . . . . . .
8
3.4
Canopy Phenology . . . . . . . . . . . . . . . . . . . .
10
3.5
Photochemical Reflectance Index (PRI) . . . . . . . .
11
3.6
Sun-Sensor-Surface Geometry Considerations . . . . .
12
3.7
Calculating Percent Reflectance from Paired Up and
Down Looking Sensors . . . . . . . . . . . . . . . . . .
15
4
Field Installation
19
5
Connecting the SRS
21
5.1
Connecting to METER Data Logger . . . . . . . . . .
21
5.2
3.5 mm Stereo Plug Wiring . . . . . . . . . . . . . . .
22
5.3
Connecting to a Non-METER Logger
. . . . . . . . .
22
5.4
Pigtail End Wiring . . . . . . . . . . . . . . . . . . . .
23
6
Communication
25
6.1
SDI-12 Communication
. . . . . . . . . . . . . . . . .
25
7
Understanding Data Outputs
27
7.1
Using METER’s Data Loggers
. . . . . . . . . . . . .
27
7.1.1
Up Looking Sensor Outputs . . . . . . . . . . .
27
7.1.2
Down Looking Sensor Outputs . . . . . . . . .
27
7.2
Using other data loggers . . . . . . . . . . . . . . . . .
28
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