BK Precision 5105B, Instruction Manual, Page: 36 / 48

36
Subject to change without notice
HORIZONTAL
CH CH
TIME / DIV
SCALE
·
VAR
X-POS
MODE
FILTER
SOURCE
TRIG ’ d
NORM
HOLD OFF
LOGIC
TRIGGER
LEVEL A/B
50s 5ns
DELAY
CH 3/4 HOR MAG
VAR x10
POWER
20
19
26
27
23
25
21
28
24
22
29
30
21.2.2 Norm
The pushbutton allows the selection of the US standard of 525
lines and 60 Hz or the European standard with 625 lines and
50 Hz. With any change of standard the line number will be
automatically changed, too.
21.2.3 Polarity
Composite video signals may have both polarities. Selection
of the right polarity is vital as the scope should be triggered by
the sync pulses and not the video content.
Positive polarity is defined by the video content being more
positive than the sync signals and vice versa.
If the polarity was wrongly selected there will be no triggering
at all, an untriggered display or no signal capture.
21.3 Menu: Logic (DSO mode only)
The following description refers to the selection of the trigger
source and the logic levels available in the ”Trig. Source“ menu
called with the pushbutton
.
The following settings may combined if these conditions are
met:
–
DSO mode.
– The trigger menu was called with ”MODE “.
– ”Logic“ was selected there. (Readout: ”Tr:Logic“.)
– The FILTER pushbutton was depressed and the ”Logic“
menu reached.
21.3.1 AND, OR: Logic AND or OR.
21.3.2 True, False
This refers to not inverting or inverting the output of the above
AND or OR function.
SOURCE (pushbutton)
Depressing this pushbutton will call various menus depending
on the previously selected mode (MODE
pushbutton): Edge,
Video, Logic. In XY mode the pushbuttons: MODE , FILTER ,
SOURCE are disabled as XY displays can not be triggered.
In the ”Trigger SOURCE“ menu the source is selected from
which the trigger signal is to be taken. The options depend on
the actual mode of the scope.
22.1 Edge-/Video-Trigger
22.1.1 CH1
Conditions: Analog or DSO mode, ”Edge“ or ”Video“ selected.
CH1 will then be the trigger source, no matter whether it is
displayed or not. Readout: ”Tr:CH1, (Slope), Filter (TV)“.
22.1.2 CH2
Conditions: Analog or DSO mode, ”Edge“ or ”Video“ selected.
CH2 will then be the trigger source, no matter whether it is
displayed or not. Readout: ”Tr:CH2, (Slope), Filter (TV).“
22.1.5 Alt. 1/2
Conditions: Analog mode, ”Edge“-Triggering“.
Alternate triggering with the signals from channels 1 and 2 as
described in the section ”Alternate Trigger“ of chapter ”Triggering
and time bases“. Please note that in this trigger mode the
apparent time relationships between the two signals on the screen
are meaningless and misleading, the relative position of the two
signals depends only on their shape and the trigger level selected.
In dual channel mode (DUAL) alternate triggering is only
possible in conjunction with alternate dual channel operation.
If previously dual trace chopped mode was selected (VERT/XY
pushbutton) > DUAL chop) it will be automatically changed
to alternate mode when alternate triggering is selected. After
”Alt. 1/2“ is turned off dual trace chopped mode may be
selected again. Readout: ”Tr:alt, Slope, Filter“.
22.1.6 External
In this mode the trigger signal comes from (TRIG
EXT
). Readout: ”Tr:alt, Slope, Filter“.
STOP
22.1.7 AC Line
The trigger signal is taken from the line which feeds the scope.
See also the section ”Line triggering“ in the chapter ”Triggering
and time bases“. Readout: ”Tr:alt, Line, Slope“.
22.2.1 Source CH1 CH2, X H L
The function pushbutton next to the display ”Source CH1 CH2“
selects one channel to serve as trigger source. The other
function pushbutton will select H = High or L = Low level.
X means that both levels will trigger (don’t care).
C o n t r o l s a n d R e a d o u t