24
Subject to change without notice
H o r i z o n t a l S y s t e m
Fig. 5.4: AM modulated signal with automatic setting
The memory depth is at least twice as much as the storage
capacity set for the maximum repeat rate (limited by the
maximum acquisition memory). The displayed sampling
rate corresponds to the current sampling rate divided by
the amount of data skipped while loading from the acquisi
-
tion memory. If peak detection is activated, the displayed
sampling rate corresponds to the current sampling rate.
All settings apply the identical current sampling rate (sampling
rate used to write to the acquisition memory). In STOP mode it
is also possible to change menu items. This does not impact the
current memory depth but the amount of displayed data will be
adjusted. Peak detection is also activated in STOP mode (time
base in microseconds).
In time bases displaying each sampling point, all three set-
tings behave identically (except used memory depth and signal
update rate). Table 5.1 displays advantages and disadvantages
of each setting.
Finally, it needs to be mentioned that this menu replaces the
adjustable memory depth, a standard for other manufacturers.
An adjustable memory depth is intended to allow users to un
-
derstand the relation between memory depth,
time base and
sampling rate and to evaluate advantages and disadvantages.
With this option, the oscilloscope always captures signals with
the maximum sampling rate. This allows users in STOP mode
to zoom in retrospectively, even at the maximum repeat rate.
It is also possible to zoom out at the maximum repeat rate if
the STOP mode was run at fast time bases. If a high repeat rate
can only be attained by means of low memory depth (as is the
case with other manufacturers) it is nearly impossible to zoom
in retrospectively in STOP mode.
The last menu INTERPOLATION allow the selection of Sinx/x,
linear or Sample-Hold as interpolation type for displaying the
aquired data points. Standard setting is Sinx/x and the best
setting for display of analogue signals. At the linear inter-
polation there is a straight line used to connect the points.
Using sample-hold type of interpolation allow the exact
examination of the position of the the aquired data points
within the signal.
5.4 Interlace Mode
In
interlace mode, converters (ADC) and storage units of two
channels within the same interlaced group are connected. This
doubles the sampling rate and the acquisition memory. Interlace
groups are channels 1 and 2 and channels 3 and 4. If an interlace
group is not interlace-capable, the non-
interlace mode is also
applied to the related group. A channel is considered active
even if it has been deactivated while still serving as the trigger
source. If a channel is activated, the respective LED next to the
input connector is illuminated.
The following conditions must be met to activate the Interlace
mode:
– no active logic pod
– none of the serial or parallel buses are active
– logic trigger not active
If the
interlace mode is possible, it will be activated automati-
cally. The following table displays channel configurations that
allow the operation in interlace mode.
Interlace group 1
Interlace group 2
CH1
CH2
CH3
CH4
On
Off
Off
Off
Off
On
Off
Off
Off
Off
On
Off
Off
Off
Off
On
On
Off
On
Off
Off
On
On
Off
Off
On
Off
On
Tab. 5.2: Channel configuration in interlace mode
Setting
Advantages
Disadvantages
Application
Max. Repeat Rate
• Many captures in one image
• Rare events can be detected more
quickly in connection with per-
sistence
• Quick response to Operation or
change in signal
• Low noise band
• High aliasing risk
• Low accuracy of details
• Low accuracy of measurements
due to reduced amount of data
• Search for rare events
• Displaying modulated signals
Maximum Sampling Rate
• Maximum accuracy of details
• Lowest aliasing risk
• High accuracy of measurements
• Slow response to operation or
change in signal
• Low signal update rate
• Higher visibility of noise
• For signals with high frequency
parts
• Assessment of small signal
details
Automatic
• Average signal update rate
• Reasonably smooth operation
• Good accuracy of measurements
• Low noise band
• Possible aliasing
• Default application
Table 5.1: Advantages and disadvantages of each setting.
