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Subject to change without notice
V e r t i c a l s y s t e m
5 Horizontal System (Time Base)
As well as
time base settings, the horizontal system comprises
the selection of the trigger position, the zoom functions and the
available modes of signal capture, the control for the
marker
function and the search fcuntions.
The knobs are used for the adjustment of the time base speed
and the trigger position. The signal capture modes are selected
in the respective menus. There is a key provided for activating
the zoom function.
5.1 Capturing modes RUN and STOP
The capturing modes can be selected with the key RUN/STOP.
In RUN mode signals will be continuously captured; depending
on the
trigger conditions selected, and displayed, erasing the
previously captured ones. If it is desired to store and further
analyze a signal and to prevent it being overwritten, capture
must be stopped by pushing the RUN/STOP key. While in STOP
mode capture is disabled and the key will light up red.
5.2 Time base adjustments
The large knob in the HORI
-
ZONTAL section of the control
panel is used for the selection
of the time base speed. The time
base speed is displayed in the
upper left hand corner above
the graticule. (e.g. „TB:500 ns“)
To the right there is the display
of the trigger time position with
respect to the normal position.
The normal trigger position is in
the center of the graticule such
that 50 % of the signal display
is before and 50 % is after this
trigger position. The X POSI
-
TION knob allows continuous
adjustment of the X position.
The available maximum values depend on the time base
setting. By pushing the key SET/CLR the value will be reset
to its reference position. The arrow keys
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allow you to
change the X position by a fixed amount of 5 divisions in the
respective direction. If marker or search function is chosen
the arrow keys together with the SET/CLR button are used to
navigate through and set/clear marker. The key MENU opens
a menu which allows you to set the X position to its minimum
and maximum positions or chose the marker function by just
a key touch. In addition, there is a submenu
NUMER.INPUT
which allows entry of an arbitrary X position. Within this menu
the search functions can be activated and set. In addition the
time reference can be set here (position for the trigger point in
time, from -5 to +5 divisions, 0 is the middle of the screen and
the standard setting).
5.3 Capture modes
The capture modes are selected by pushing the key ACQUIRE,
this opens a display menu which offers the basic modes of
capture:
5.3.1 Refresh:
In this mode the signals are captured and displayed.
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D
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37
41
39
42
43
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Fig. 5.1: Control panel of the
horizontal system
5.3.2 Roll:
This
acquisition mode is intended specifically for very slow
signals, with the untriggered signal „rolling“ across the screen
from right to left (requires signals slower than 200 kHz). The
HMO uses a ring buffer to store the signal values in roll mode.
Simply put, the instrument writes the first division to the first
storage space, the second division to the second storage space,
etc. Once the storage is full, the instrument overwrites the first
storage space with the data of the most recent measurement
value. This creates a „ring“ or cycle run, similar to a ticker.
The ZOOM feature is not available in the roll mode
(also refer to chapter 5.5 ZOOM Function).
5.3.3: ENVELOPE:
In this mode, the display includes the normal capture of each
signal and the maximum as well as the minimum values of
each capture. Over time, this creates an envelope surrounding
the signal.
5.3.4: AVERAGE:
In this mode, you can use the
universal knob in the Cursor/
Menu section of the control panel to set the number of signal
periods for averaging, available in powers of 2 from 2 to 1024
(requires repetitive signals).
5.3.5: FILTER:
In this mode, you can activate a low pass filter with adjustable
cut off frequency to suppress unwanted high frequency inter
-
ferences. The cut off frequency can be set based on the sam
-
pling frequency. The minimum setting is 1/100 of the sampling
frequency and the maximum value is 1/4 of the sampling rate.
You can select this setting with the
universal knob.
The second menu page is accessed by pushing the soft key
next to the menu „Page 1I2“, here, extended functions are
available:
5.3.6 Peak Detect
This mode is used for very large time base settings to detect
even short signal changes. You can also deactivate this func-
tion within the menu or you can select the automatic switching
mode. The following conditions must be met to activate the
PEAK DETECT
mode:
– Function HIGH RESOLUTION is deactivated
– None of the serial or parallel buses are active
During peak detection, the oscilloscope distinguishes between
two types: Acquisition peak detection and memory peak de
-
tection.
Each A/D converter converts at the full sampling rate (no
Interlace mode), even if results have not been written to the
acquisition memory at full
sampling rate (for slow time bases,
for instance). If peak detection is activated, unused converter
values will be evaluated to detect minimum and maximum
amplitudes. During this process, the identified minimum and
maximum values including sampling interval are written to the
acquisition memory. As a result, the acquisition memory stores
data pairs representing the signal sequence according to the
sampling interval. The smallest detectable pulse is the period of
the maximum sampling rate (no Interlace mode). This describes
the so-called acquisition peak detection.
A hardware peak detection is not available if data is written
to the acquisition memory at the ADC‘s maximum sampling
rate. For slow time bases and a repeat rate set to automatic
or maximum value, not all data from the acquisition memory
