System Overview
R&S
®
CMW500
67
User Manual 1173.9463.02 ─ 02
4.3.4.5
Standard Deviation
The "Standard Deviation" σ
n
indicates the spread of the n values at each measurement
point. It is defined as the square root of the variance, which is the mean square of the
deviation of the values from their own arithmetic mean.
The variance can be calculated using the following recursive equation:
with the arithmetic mean value:
The formula above is modified for the magnitude error and the phase error, where positive
and negative contributions tend to compensate each other. The arithmetic mean value
and the standard deviation of these quantities is obtained from the absolute values.
4.3.5 Limit Check
Limits specify the allowed range for a particular set of measurement results. Typically,
limits are used to check whether a DUT conforms to the rated specifications (conformance
testing):
●
An upper limit L
upp
defines the maximum value for the measurement result R: L
upp
>
R.
●
A lower limit L
low
defines the minimum value for the measurement result R: L
low
< R.
●
A symmetric limit L
sym
defines the maximum value for the absolute value of the mea-
surement result R: R must be in the symmetric range -L
sym
< R < L
sym
.
A limit check consists of comparing the measurement results to the limits and displaying
a pass/fail indication.
The R&S CMW500 provides different tools for viewing limits and limit check results.
●
Limit lines show the upper, lower, or symmetric limits for a series of measurement
results (measurement trace). In the measurement diagrams, limit lines are displayed
in red color. A limit line consisting of different sections is termed a template.
●
A pass/fail indication in a table of measurement results shows the limit check result
for a single or a statistical result.
Measurements
