2-28
IM 701240-01E
2.4
Setting Waveform Acquisition Conditions and
Display Conditions
Acquisition Mode «For procedures, see sections 7.2 and 7.3.»
When storing sampled data in the acquisition memory, it is possible to perform
processing on data and display waveforms based on the processed data. The following
four types of data processing are available.
Normal Mode
In this mode, sampled data are stored in the acquisition memory without data
processing.
Averaging Mode
Averaging
is a process in which waveforms are acquired repeatedly to obtain the
average of waveform data at the same time point (the same time in relation to the trigger
point).
The SL1400 takes the simple or exponential average of the waveform data and writes
the results to the acquisition memory. The averaged data is then used to generate the
display. You can set the attenuation constant to a value between 2 and 256 (in 2
n
steps,
where n is a natural number) and the averaging count to a value between 2 and 65536.
An = {(N –
1)A
n–1
+ X
n
}
1
N
Exponential average (when set to infinite)
A
N
=
N
Simple average (when set to 2 to 65536)
N
n = 1
Σ
X
n
An
Xn
N
: n
th
averaged value
: n
th
measured value
: Attenuation (2 to 256, 2
n
steps)
Xn
N
: n
th
measured value
: Average count
(acquisition count, 2
n
steps)
Averaging is effective such as when eliminating the random noise riding on the signal.
Envelope Mode
In normal mode and averaging mode, if you increase the record time, you must reduce
the sample rate (the number of times data is acquired per second in the acquisition
memory) to keep the record length of the acquisition memory the same (see appendix 1).
However, in the envelope mode, the maximum and minimum values are determined at
every time interval from the data sampled at the maximum sample rate of each input
module. The time interval used to determine the values is twice the sample rate of the
normal mode. The maximum and minimum values are paired and stored in the
acquisition memory.
Envelope mode is effective when you want to avoid aliasing, since the sample rate is
kept high irrespective of the time axis setting. It is also effective when you want to detect
glitches (pulse signals which rise very fast) or display an envelope of a modulating
signal.
Envelope curve
