6.4 Averaging
The
average value
of the measured value is required for various applications :
e.g.
the average flow velocity in a ventilation channel
smoothing of a widely fluctuating measured value
(e.g. wind, pressure etc.)
hourly or daily average values of weather data (temperature, wind etc.)
as above, for consumption values (current, water, gas, etc.)
The average value of a measured value is obtained by adding together a se-
M
ries of measured values M
i
and then dividing this sum by the number N of mea-
sured values in the series :
Average valuet M =
i
(
Σ
M
i
)
/N
6.4.1 Smoothing out meas. val. by means of a sliding average
When measuring values of an unstable or strongly fluctuating nature, e.g. par-
ticularly turbulent flows, it is an advantage to smooth the values by means of
continuous averaging. The level of smoothing can be set, via the ´Smoothing
level´ function
´DG´
, within a range of 0 to 99 (see Section 5.2). This level spe-
cifies the number of measuring operations at the selected measuring point from
which the sliding average is to be taken. The smoothed measured value can
then be read out in the MEASURED VALUE function; this will also apply for all
subsequent evaluation functions. Smoothing can thus also be used in con-
junction with averaging (see Section 6.4.3) e.g. for network measurements.
SMOOTHING LEVEL function
´DG´
Select by key:
...
1: 1 0
DG
Enter as per Section 5.4
Measured value smoothing is only possible for the selected chan-
nel. When a large number of measuring points is involved, conti-
nuous measuring point scanning should be switched off; otherwise
the filter effect may be substantially restricted
.
6.4.2 Averaging mode
All averaging operations, except when smoothing a measured value, are speci-
fied via AVERAGING MODE
´MM´
; the average value appears in the AVERAGE
VALUE function
´MW´
; the number of averaged values appears in the NUMBER
function
´C´
. As and when the averaging mode is programmed, these last two
functions
´MW´
and
´C´
are activated automatically. Averaging mode is activated
by default and is selected by pressing the
FUNKTION
key.
AVERAGING mode function
´
MM
´
Select by key:
...
FUNCTION
1: C o n t
MM
FUNCTION
30
ALMEMO
®
8390-2
Measuring operations
