Campbell CR7, Instruction Manual, Page: 108 / 186

SECTION 10. PROCESSING INSTRUCTIONS
10-6
PAR. DATA
NO.
TYPE DESCRIPTION
01: 4 Input location no. of atmospheric
pressure in kilopascals
[PRESSURE]
02: 4 Input location no. of dry-bulb
temp.
[DB TEMP.]
03: 4 Input location no. of wet-bulb
temp.
[WB TEMP.]
04: 4 Dest. input location for vapor
pressure
[VP or Z]
Input locations altered: 1
*** 58 LOW PASS FILTER ***
FUNCTION
Apply a numerical approximation to an analog
resistor capacitor (RC) low pass (LP) filter using
the following algorithm:
F(Xi) = W*Xi + F(Xi-1) * (1-W)
Where, X = input sample,
W = user entered weighting function,
O< W <1
If W=O, F(Xi)=O; if W=1, F(Xi)=X,
F(Xi-1) = output calculated for previous sample.
The equivalent RC time constant is given by
T/W, where T is the sampling time in seconds.
For values of W less than 0.25, the analogous
"cut off" frequency (the frequency where the
ratio of output to input is .707) is accurately
represented by W/(2
Π
T). For larger values of
W, this "analog" estimate of the cutoff frequency
becomes less representative.
On the first execution after compiling, F(x) is set
equal to X.
PAR. DATA
NO.
TYPE DESCRIPTION
01: 2 Repetitions [REPS]
02: 4 First input location for input data
[X]
03: 4 Dest. input location for filtered
data
[F(X) or Z]
04: FP Weighting function, W [W]
Input locations altered: 1 per repetition
*** 59 BRIDGE TRANSFORM ***
FUNCTION
This instruction is used to aid in the conversion
of a ratiometric Bridge measurement by
obtaining the value for Rs which is equivalent to
Rf[X/(1-X)], where X is the value derived by the
standard CR7 Bridge Measurement Programs
(with appropriate multiplier and offset, Section
13.5) and Rf represents the MULTIPLIER value.
The result of Instruction 59 is stored in the
same location that X was.
PAR. DATA
NO.
TYPE DESCRIPTION
01: 2 Repetitions [REPS]
02: 4 Starting input location and
destination
[X]
03: FP Multiplier (R
f
) [MULT.]
Input locations altered: 1 per repetition
*** 61 INDIRECT INDEXED MOVE ***
FUNCTION
Moves input data from location X to location Y,
where X and Y are indirectly addressed. The
values of the location numbers X and Y are
stored in the locations specified by Parameters
1 and 2. The CR7 looks in the locations
specified in the parameters to find the locations
to use as the source and destination of the data.
When used within a LOOP, a location
parameter can be specified as "indexed"
(xxxx-), then the actual Input location
referenced is calculated by adding the current
index counter to the value in the specified Input
location.
PAR. DATA
NO.
TYPE DESCRIPTION
01: 4 Input location containing source
location X
02: 4 Input location containing destination
location Y
*** 62 COVARIANCE/CORRELATION ***
FUNCTION
The special Covariance/Correlation Instruction
(CV/CR) for the CR7 calculates: 1) means (M),
2) variances (V), 3) standard deviations (SD), 4)
covariances (CV), and 5) correlations (CR) for a
set of input values and stores the results in