Installing The Srs; Attaching And Leveling; Cleaning And Maintenance - Decagon Devices SRS Operator's Manual

Spectral reflectance sensor

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SRS Sensors

Installing the SRS

7.1

The SRS comes with a variety of mounting hardware, allowing it

to be mounted on posts, rebar, poles, tripods, etc. The mounting

hardware allows for vertical adjustment and orientation on the pole

and allows for sensor tilt. Up-facing sensors have Teﬂon diﬀusers

and measure radiation from the entire upper hemisphere. The sen-

sor therefore needs to be leveled and mounted in a location where it

will not be shaded and has an unobstructed view of the sky.

For down-facing sensors, the SRS can be mounted any distance from

the canopy, but it is important to keep in mind that the inﬂuence of

individual plants on the reading increases as the sensor gets closer

to the canopy.

You may use hemispherical down facing sensors, but make sure to

mount them facing directly down so they are not "seeing" sky. The

inﬂuence of the pole and sky can be avoided by using ﬁeld stop ra-

diometers. These will average over just the area within the 20 ﬁeld

of view where you aimed them. Assure that the area they see is

representative and carefully choose the view elevation and azimuth.

When the view angle is directly away from the sun the sensor sees

mostly sunlit leaves. If it points perpendicular to the sun rays the

sensor will see an increased fraction of shadow. Field stop sensors are

intended for measuring canopy-reﬂected radiation and should not be

mounted in an up facing orientation.

7.2

Optical surfaces need to be kept clean and free from dust, debris and

deposits. Clean surfaces with water and a soft cloth as necessary.

Return the radiometer to the factory for recalibration after approxi-

mately one year of outdoor exposure. See section 8.3 for more details

on calibration.

7 INSTALLING THE SRS

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