19
Subject to change without notice
AUTOSET
For specific information consult ”Controls and Readout“
AUTOSET
7
.
AUTOSET enables a standard automatic instrument setting, if
the applied signal meets the amplitude and frequency require-
ments of automatic triggering.
All controls except for the POWER switch are electronically
scanned and therefore can also be controlled by the micro-
computer.
This is a precondition for AUTOSET as this function must be able
to control all functions independent of control settings. AUTO-
SET will always switch to YT mode, but preserve the previous
selection of CH1, CH2 or dual trace; ADD or XY modes will be
switched to dual trace Yt.
Automatic setting of the vertical sensitivities and the time base
will present a display within 6 cm height (4 cm per signal in dual
trace) and about 2 signal periods. This is true for signals not
differing too much from a 1:1 duty cycle. For signals containing
several frequencies like video signals the display may be any.
Initiating the AUTOSET function will set the following operating
conditions:
– last selection of AC or DC coupling
– internal
triggering
– automatic
triggering
– trigger level set to the center of its range
– calibrated
Y
sensitivities
– calibrated
time
base
– AC or DC trigger coupling unmodifi ed
– HF trigger coupling switched to DC
– LF or Noise Reject fi lters left
– X
magnifi er switched off
– Y and X positioning automatic
Please note:
For pulse signals with duty cycles approaching 400:1 no au-
tomatic signal display will be possible.
In such cases switch to normal trigger mode and set the trigger
position about 5 mm above the centre. If the trigger LED will then
light up a trigger is generated and the time base is operating. In
order to obtain a visible display it may be necessary to change
the time base and V/DIV settings. Depending on the duty cycle
and the frequency the signal may still remain invisible.
which can be varied such that TB A functions as a precision
time delay generator. Depending on the amplitude of the com-
parison voltage a signal is generated anywhere between sweep
start and end.
In one of two operating modes this signal will start TB B imme-
diately. The TB A display will be intensifi ed for the duration of
TB B, so that one sees which portion of the signal is covered by
TB B. By varying the comparison voltage the start of TB B can
be moved over the whole signal as it is displayed by TB A. Then
the mode is switched to TB B. The signal portion thus selected is
now displayed by TB B. This is called „B delayed by A“. Portions
of the signal can thus be expanded enormously, however, the
higher the speed of TB B, the darker the display will become,
the rep rate will remain that of the input trigger signal triggers
while the duration of TB B is reduced with increasing speed.
The readout display is not affected.
In cases where there is jitter the TB B can be switched to wait
for a trigger rather than starting immediately. When a trigger
arrives TB B will be started on it. The jitter is removed, however,
the effect is also, that the TB B start now can be only from signal
period to signal period, no continuous adjustment is possible
in this mode.
Alternate sweep
In this mode the signal is displayed twice, with both time bases.
An artifi cial Y offset can be added in order to separate the two
displays on the screen. The operation is analogous to Y dual
trace alternate mode, i.e., the signal is alternately displayed by
both time bases, not simultaneously which is not possible with
a single gun crt. TB B operation is the same here.
T r i g g e r i n g a n d t i m e b a s e
