Tektronix RSA2200A, Руководство пользователя

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Trace Comparison Display and Average Function
RSA2203A & RSA2208A User Manual
3- 115
Averaging the Waveform
The averaging technique is generally used to average and reduce the noise of the
waveform. The average function includes the peak hold which maintains the
maximum and minimum values as well as the averaging process.
There are four averaging types as follows, where these variables are used:
X(p)
n
: Display data for the n
th
frame
x(p)
n
: Active data for the n
th
frame
P : Frame point
N : Value of “Number of Averages”
RMS.
Root-mean-square. Used when acquiring data in single mode. N frames
average, then the acquisition stops.
X(p )
n
=
x(p )
n
for : n = 1
for : 2
≦
n
≦
N
X ( p )
n
=
x ( p )
N
for : n > N
X ( p )
n
=
(n–1)
×
X ( p )
n– 1
+
x ( p )
n
n
Exponential RMS.
Exponential root-mean-square. Used when acquiring data in
continuous mode. Continuous averaging weights older sweeps so that they have
a progressively smaller effect on the average.
X ( p )
n
=
(n–1)
×
X ( p )
n– 1
+
x ( p )
n
n
X(p )
n
=
x(p )
n
for : n = 1
for : 2
≦
n
≦
N
X ( p )
n
=
(N – 1)
×
X ( p )
n– 1
+
x ( p )
n
N
for : n
>
N
Max Hold.
Displays only the maximum value at each data point.
X(p )
n
=
x(p )
n
for : n = 1
X ( p )
n
=
max(X ( p )
n– 1 ,
x ( p )
n
)
for : n
≧
2
Min Hold.
Displays only the minimum value at each data point.
X(p )
n
=
x(p )
n
for : n = 1
X ( p )
n
=
min(X ( p )
n– 1 ,
x ( p )
n
)
for : n
≧
2
Average Type