Ex-Del-Se (P4) Instruction - Campbell 05103 Instruction Manual

Appendix B. Wind Direction Measurement Theory
B.2 EX-DEL-SE (P4) Instruction
B-2
Instruction 4 outputs a precise excitation voltage (V
between the wiper and analog ground, V
and analog ground, R , and V
s
the measured voltage, V . This measured voltage is related to resistance as
s
shown below:
( )
= ⋅ +
V V R R R
s x s t s
The maximum value that R will reach is R
s
west side of north to the east side of north (at this point R
maximum value of V . This maximum voltage equals 2500 mV for an
x
excitation voltage of 2500 mV recommended for the CR10(X) and 5000 mV
for an excitation voltage of 5000 mV recommended for the CR23X at 355
degrees. The multiplier to convert V
0.142 for the CR10X, or, 355 degrees / 5000 mV = 0.071 for the CR23X. See
Section 13.5 in the datalogger manual from more information on the bridge
measurements
) and measures the voltage
x
. The resistance between the wiper
s
varies with wind direction. Instruction 4 outputs
s
just before it crosses over from the
f
t
to degrees is 355 degrees / 2500 mV =
s
= 0). V reaches its
s