Instruction manual

13
Subject to change without notice
when switched back to analog mode, the time base
in analog mode will be set to the value selected in the
digital mode (e.g. 2µs/div).
2.If a time base between 100s/div and 1s/div has been
set in the digital mode and the mode is switched to
analog, then the time base in analog mode is
automatically set to 500ms/div. The rest is as described
before.
The X-MAG x10 setting remains unchanged when
switched from analog to digital mode and vice versa.
STORAGE MODE ONLY
If by pressing and holding the STOR. ON / HOLD
pushbutton, the mode is switched to digital, then one
of the associated LED’s lights up. Which one,
depends on the last selected digital operation.
Exception
Switching over from analog SINGLE mode to di-
gital mode sets the instrument automatically to
digital SINGLE mode.
For additional information regarding the digital mode,
see section STORAGE OPERATION.
HOLD
STORAGE MODE ONLY
Briefly pressing the STOR. ON / HOLD pushbutton
switches over between protected and unprotected mode
of the current memory contents.
The current contents of the memory are protected
against overwriting when HLD (HOLD) instead of
channel information (e.g. Y1... ) is displayed in the
readout. This prevents a change in the Yt mode setting,
but it is possible to select between DUAL (Yt) and XY
display by pressing the DUAL (23) pushbutton if one of
these modes was selected before activating HOLD.
If HOLD is switched off, one can observe how the
existing memory contents are successively overwritten
by new data especially with slow time base settings
and refresh mode. Protecting the memory contents in
the middle of a data acquisition process can result in an
irregularity at the junction of old (right) and new data
(left). This can be avoided by recording in single shot
mode (SGL), even though the input signal is repetitive.
At the end of a sweep, one can use HOLD to protect
the contents against being overwritten by an uninten-
tional actuation of RESET (RES).
The signal in each of the current memory can be shifted
in the vertical direction (+/- 4div) with the corresponding
Y-POS rotary knob when HOLD is operative.
The original trace position will be lost when shifted
vertically, but this can be found again. To this end the Y-
POS knob in question must be rotated quickly. Once
the original position is reached, the trace does not shift
anymore although the knob is rotated further. Simul-
taneously a signal tone sounds. To shift the trace verti-
cally again it will be required to stop rotating the knob
for at least about 2 seconds.
Attention!
The dynamic range limits of the A/D converter may
become visible if a Y -position shift is performed after
storage. This can affect those signal parts which were
originally above or below the screen.
(8) PTR / PK Det - Pushbutton with two functions.
Neither function is available in analog mode.
PTR
Briefly pressing selects the PRE- and POST-Trigger value.
The PRE TRIGGER function is used to capture signals
that occur prior to a trigger event, making the prehistory
visible. In contrast to this function, the POST TRIGGER
is used to capture signals occurring after the trigger
event, which could not be captured in “0%” pre trigger
condition. Due to the dependence on trigger events,
neither function is available in the trigger independent
modes XY and ROLL.
The actual PRE- or POST TRIGGER value is displayed
by the readout and changes each time the PTR
pushbutton is pressed briefly, in the following sequence:
PT0%, PT25%, PT50%, PT75%, PT100%, PT-75%, PT-
50%, PT-25% and back to PT0%.
The values refer to the X-axis (graticule) of the screen
display (10% = 1div).
The following description assumes that the X magnifier
(x10) is inactive and the signal display starts on the
leftmost vertical graticule line. It is also assumed that a
trigger mode (source, coupling) is chosen, in which the
trigger point symbol is displayed. In contrast to analog
mode, using pre trigger the trigger point symbol can be
shifted in X-direction.
PRE TRIGGER
0% PRE TRIGGER (readout ”PT0%”) means that the
signal display starts with the trigger event. The trigger
point symbol indicates this position. If the X-POS. control
is not in center position, an arrow pointing to the left
may be displayed. Then the X-POS. (19) control must
be turned clockwise until the arrow is no longer visible.
25% PRE TRIGGER (readout ”PT25%”) is achieved after
pressing the PTR pushbutton once. The signal display
starts with 25% prehistory and the trigger point symbol
is shifted 2.5 divisions to the right.
Each time the PTR pushbutton is pressed the PRE
TRIGGER value increases by 25% until 100% is reached.
If in 100% condition an arrow symbol is displayed in
addition to the trigger point symbol, the X-POS. control
should be turned ccw. to make the trigger point visible
on the screen.
The duration of the prehistory is determined by multi-
plying the time coefficient by the pre trigger value (in
divisions). E.g. 20ms/div x 7,5 div (= 75% pre trigger) =
150ms.
POST TRIGGER
In POST TRIGGER condition the trigger point is always
to the left of the screen and therefore not visible. The
trigger point symbol then only indicates the LEVEL
Controls and Readout