SunScan User Manual v 1.05
Introduction
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7
SunScan probe
The light sensitive “wand” of the probe is 1 metre long, containing 64 photodiodes
equally spaced along its length. The probe handle contains batteries and electronics
for converting the photodiode outputs into digital PAR readings, which get sent to
your Data Collection Terminal via the RS232 link.
Beam Fraction sensor
The Beam Fraction sensor (BFS) also measures PAR light levels. It is used to
monitor the light incident on the canopy at the same time as you are making
measurements beneath it. The BFS incorporates two photodiodes, one of which can
be shaded from the direct solar beam by the shade ring. This allows the direct and
diffuse components of PAR to be separated, which is necessary for the computation
of LAI.
Data Collection Terminal
To observe and store readings from the SunScan probe, you need the Data Collection
Terminal (a Psion Workabout). The Workabout is a lightweight, robust field unit
with a full alphabetic keyboard for the annotation of readings. It comes with a
removable Flashcard which can be used for data storage and transfer.
You can use a portable PC as a data collection terminal instead, but it is less
convenient for field work.
SunData software
In order for the SunScan probe to communicate with the Workabout or a PC, it needs
software. We pre-install the Workabout's SunData software, and we provide the
SunData PC software on a 3.5 inch diskette which you must load into your PC. The
SunData PC software is a DOS program; it does not require Windows, but it can be
run in a DOS window. Data files are created in an ASCII text format which you can
import into spreadsheets or other applications for analysis on any PC.
Field accessories
The sturdy field Carrying Case is designed to accommodate all the components of
the SunScan system. It has room for an optional tripod mount which is intended
primarily for use with the BFS, but which can equally well be used with the SunScan
probe. Space is also provided for extension cables that may be ordered with the BFS.
