7-2
IM 701310-01E
Explanation
Acquisition Modes
You can select the acquisition mode from one of the following. The default setting is
Normal.
• Normal Mode
The DL9000 saves sampled data to the acquisition memory without performing any
special data processing.
• Envelope Mode
The maximum and minimum values are determined every acquisition interval from the
data sampled at 2.5 GS/s (DL9040/DL9040L/DL9140/DL9140L) or 5 GS/s (DL9240/
DL9240L). The maximum and minimum values are stored in the acquisition memory
and an envelope waveform is displayed.
• Averaging Mode
The DL9000 averages the sampled data and saves it to the acquisition memory. The
averaging method varies depending on the trigger mode.
• When the trigger mode is Auto, Auto Level, or Normal, exponential averaging is
used. Set the attenuation constant to a value from 2 to 1024.
• When the trigger mode is Single or N Single, simple averaging is used. Set the
sampled data acquisition count to a value from 2 to 65536.
• In Single mode, set the acquisition count from the acquisition mode menu.
• In N Single mode, set the acquisition count from the trigger mode menu.
An = {(N – 1)A
n–1
+ X
n
}
1
N
Exponential average
(When the trigger mode is Auto, Auto Level, or Normal)
AN = N
Simple average
(When the trigger mode is Single or N Single)
N
n = 1
Σ
X
n
An:
Xn:
N:
n
th
average
n
th
measured value
Attenuation constant
(2 to 1024, in powers-of-2 increments)
Xn:
N:
n
th
measured value
Acquisition count
(2 to 65536, in powers-of-2 increments)
Notes about Averaging
• Only repeating signals are averaged.
• If the trigger is not consistent, and the waveform is not completely synchronized, the
signal will not be averaged correctly, and the waveform will be distorted.
• Roll mode is not valid when averaging is used.
• If you stop acquisition by pressing START/STOP, averaging will also stop. When you
restart acquisition, values will be averaged from the beginning.
• With simple averaging, acquisition stops when the signal has been acquired for the
number of times set by the acquisition count.
• When a signal is acquired in averaging mode, the following data is saved to the history
memory.
• Exponential averaging when the trigger mode is Auto, Auto Level, or Normal
Each waveform averaged over a set time interval is saved to a separate record.
• Simple averaging when the trigger mode is Single
The DL9000 averages the set number of waveforms, and saves the averaged
waveform to the most recent history memory record.
• Simple averaging when the trigger mode is N Single
The DL9000 saves the set number of waveforms to the history memory and saves
the waveform that is the average of those waveforms to a separate section in the
history memory.
• The maximum length of records for which averaging is possible is 625 KW for
DL9040/DL9140/DL9240, and 1.25 MW for DL9040L/DL9140L/DL9240L.
7.1 Setting the Acquisition Mode
