39
Subject to change without notice
26.1.1
X POS
If the pushbutton is dark the HORIZONTAL knob
27
functions as
X position control, i.e. it moves the signal display horizontally.
The position control is especially useful when the magnifier
(MAG. x 10
29
) is switched on. The magnifier will magnify the
display 10 times around the screen centre. Using the POS
control, the portion of the signal to be studied can be shifted
on the screen.
26.1.2
DELAY
In order to change the function of the HORIZONTAL knob
27
to
”Delay“ proceed as follows:
Press the HOR VAR pushbutton
30
which will present the ”Time
base“ menu, select ”Search“ or ”B only“, then the function of the
knob will be changed if the pushbutton is depressed. It will light
up to show that the knob is now the delay time control.
In ”Search“ mode both traces (time base A and B) alternate.
Unlike the former time base ”A only“ mode, a sector with hig-
her intensity is visible on the A trace. This sector can be moved
continuously by the delay time control. The time between the
A trace start and the beginning of the intensified sector is the
delay time. This information is also displayed in the readout (”Dt:
…“) and is an aid to find the position of the intensified sector
which may be very small. If time base ”B only“ is chosen the
intensified sector is no longer visible, but the DELAY function
still can be used.
Without activated ”B Trigger“ function, the B time base will be
started after the A time base delay time ”elapsed“.
26.2 Digital mode
The pushbutton will indicate the actual function in accordance
with the front panel lettering:
dark = Post- and Pre Trigger control (moves the trigger point
in horizontal direction).
green = Delay time control for horizontal Zoom position=
shift.
26.2.1
X-POS delay
If the pushbutton is dark the HORIZONTAL
27
knob functions as X
position control of the trigger time, i.e. it moves the trigger point
symbol horizontally. This allows display of signal portions before
and after the trigger, called Pre Trigger and Post Trigger. If the
trigger point symbol is located on the screen centre the readout
will show ”Tt:0s“, hence the trigger time indication is always re-
ferred to the screen centre. Values with a positive sign are Post
Trigger times, those with a negative sign Pre Trigger times.
If the X POS DELAY pushbutton is depressed the ”Hor.Knob“
menu will be called, it contains the following options:
1
st
Centre: Pressing the function pushbutton ”Center“ will set
the trigger time to the screen centre ”Tt:0s“ which is the
standard setting.
2
nd
Coarse On Off: changes the speed of the HORIZONTAL
knob.
26.2.2
DELAY Zoom Pos
This pushbutton will be illuminated if the ”Time base“ menu was
called with the HOR VAR
30
pushbutton and ”Search“ selected. The
HORIZONTAL
27
knob can then be used to select a portion of the
time base display which is to be displayed expanded in time.
In ”Search“ mode the normal and the expanded displays are
displayed simultaneously, if neither reference nor mathematic
signals are displayed. The expanded portion of the signal will
be shown on the normal display as an intensified sector. The
length of this sector is dependent upon the setting of the 2nd
”Z“, time base which is shown in the readout as ”Z...“ and is
equal to the run time of the Z time base.
27
HORIZONTAL
(knob)
The various functions of this knob depend on the operating mode
and are described under X POS DELAY pushbutton
26
.
FFT (digital mode only)
As in Yt mode this knob moves the display in X direction. This
changes the frequency range and consequently the center
frequency setting displayed in the readout.
28
TIME
/
DIV.–SCALE–VAR
(knob)
This knob is normally used as the time base speed selector, but
has also other functions dependent on the operating mode. In
XY mode this control is disabled.
28.1 Analog mode
28.1.1
Time base A time/cm selection
This function is active if in the ”Time base“ menu (HOR VAR
pushbutton
30
) ”A only“ is selected and the option ”A variable
On Off“ is set to Off.
Turning the knob CCW will decrease, turning it CW will increa-
se the time base speed. The time base speed may be chosen
between 500 ms/cm... 20 ns/cm in a 1-2-5 sequence and will be
calibrated. The readout will show the setting (e.g. ”A:20ns“).
28.1.2
Time base B time/cm selection
This function is active if in the ”Time base“ menu HOR VAR
pushbutton
30
) ”Search“ or ”B only“ was selected and the option
”B variable On Off“ was set to Off. Turning the control CCW will
decrease, turning it CW will increase the time base speed. The
speed can be selected between 20 ms/cm.. 20 ns/cm in a 1-2-5
sequence and will be calibrated. The readout will show the speed
(e.g. ”B:20ns“). The time base B allows display of portions of
the time base A display on an expanded time base scale. This
implies that the speed of TB B must always be greater than that
of TB A. Therefore with the exception of 20 ns/cm TB B can not
be set to the same speed as TB A or slower.
Further information is available in the section ”Time base B (2
nd
time base) / Delay / Triggering“ (Analog mode) in the chapter
”Triggering and time bases“.
28.1.3
Variable
The TIME/DIV–SCALE–VAR control may also be used to change
the time base speed continuously but uncalibrated. VAR will
light up on top of the HOR VAR pushbutton
30
in order to warn
that the time base is uncalibrated and the knob has now that
function.
In order to arrive at that function press HOR VAR pushbutton
30
which calls the ”Time base“ menu. Depending whether time
base A or B is selected either ”A variable On Off“ or ”B variable
On Off“ will be shown. The function pushbutton can then be
used to select On/Off.
In order to point out that the time base is now uncalibrated
the readout will replace ”:“ by ”
>
“ preceding the time/cm. (e.g.
”A
>
500ns“ and ”B
>
200ns“). Also the results of cursor time/pe-
riod measurements will be marked that way.
28.2 Yt digital mode
28.2.1
ZOOM OFF
(A time base time/cm selection)
Select the menu ”Zoom“ by pressing HOR VAR pushbutton
30
and then ”Off“ in order to set the function of the knob TIME/DIV–
SCALE–VAR to time base A speed as in analog mode. If ”Zoom
C o n t r o l s a n d R e a d o u t