Tektronix 7834 User Manual

Theory of Operation-7834
HORIZONTAL
CHOPPED
BLANKING
A MODE
B MODE
B MODE
ALTERNATE PULSE
CHOP MODE (HORIZ)
(1195-10) 1988-35
MAIN
FRAME
CHANNEL
SWITCH
SIGNAL
Figure 3-10 . Input and output pins for horizontal binary IC
(U4358) .
The Horizontal Binary stage operates as
follows for each
position of the HORIZONTAL MODE switch (refer to
Figure 3-11 B for input/output conditions) :
1 . A MODE . When the HORIZONTAL
MODE switch is
set to A, Display B is LO to indicate to
all circuits that the
A HORIZ unit is to be displayed .
2 . B MODE . Selecting the B HORIZONTAL MODE pro-
vides a HI Display B signal to all circuits .
3 . CHOP MODE . In the CHOP position of
the
HORIZON-
TAL MODE switch, the Display
B
signal switches
between
the
H
I and LO levels to produce a
display that switches
between the A and
B HORIZ units
at a
0 .2 megahertz rate .
The repetition rate of Display B in this mode is
determined
by the Horizontal Chopped Blanking pulse (see Chop
Counter description) . Each time the Horizontal
Chopped
Blanking pulse at pin 1 drops
LO, the output at pin 6
switches to the opposite
state .
4 . ALT MODE . For
ALT HORIZONTAL MODE opera-
tion, the Display
B
signal
switches to the opposite state
each time the negative portion of
the Alternate Pulse is
received from the Horizontal Logic stage
. Repetition rate of
Display B in this mode is one-half
the repetition rate of the
Alternate Pulse applied to pin 8 .
Figure 3-11A shows a
logic diagram for the Horizontal
Binary stage . An input/output table showing the conditions
for each position of the HORIZONTAL MODE switch is
shown in Figure 3-11 B .
Vertical Binary
The Vertical Binary stage produces the Vertical Alternate
Command
to
determine which vertical unit is to be displayed
3-
1 8
when the VERTICAL MODE switch
is set for ALT . When
this output level is HI, the RIGHT
VERT unit is displayed ;
when it is LO, the LEFT
VERT
unit is
displayed . In the
ALT or CHOP positions of
the HORIZONTAL MODE
switch (non-delayed operation
only), the output of this
stage is slaved to the output of
the Horizontal Binary stage
so that the Vertical Alternate
Command is always HI when
Display B is LO, and vice
versa
.
'This action allows
independent-pairs operation
(sweep-slaving) in the ALT
position of the VERTICAL
MODE switch and the ALT or
CHOP positions of the
HORIZONTAL MODE switch,
whereby the LEFT VERT unit is
always displayed at the
sweep rate of the B time-base and
the RIGHT VERT unit
is displayed at the sweep rate of
the A time-base . Thus,
independent-pairs operation can
simulate dual-beam opera-
tion for repetitive sweeps .
When the
A time-base unit is set to the delaying mode, the
repetition rate of the
Vertical Alternate Command is one-
half the repetition rate of Display
B . This results in each
vertical unit being displayed
first against the A time-base
unit (delaying), then the
B time-base unit (delayed), before
the display is
switched to the other vertical unit .
The Vertical Alternate Command is used in
the Plug-In
Binary and Vertical Mode Logic stages
.
Figure 3-12 identifies the
function of the input pins for the
Vertical Binary IC (U4368) .
This stage uses the same type
of IC as the Horizontal
Binary stage . Notice the Display
A
level at pin 7 . This
input is the inverse of the Display
B
level at pin 8 .
Therefore, the Display A level is always
HI
when the Display
B level is LO, and vice versa (04364
generates the Display
A level)
.
Also, notice the line con-
nected to pin 4 of the
Vertical Binary IC U4368 . The level
at pin 4 is generated
by 04424 and is HI only when the
HORIZONTAL
MODE switch is set for ALT or CHOP and
the
A time-base unit is set for nondelayed operation .
The
Vertical
Binary IC uses the information at pin 4 for correct
slaving of the
Vertical Alternate Command to the Display B
signal (necessary for
independent-pairs operation) .
The following discussions describe the operation of the
Vertical
Binary
stage
in relation to the modes of operation
that can occur
.
1 . A OR B MODE . When the HORIZONTAL
MODE
switch is set to either A or B, the Vertical Alternate com-
mand will switch to the opposite state each
time an Alter-
nate Pulse is received from the
Horizontal Logic stage .
Repetition rate of the Vertical Alternate
Command in this
mode is one-half the repetition
rate of the Alternate Pulse .
The input conditions for these modes are :
Pin 1 LO-Alternate Pulse generated by the
Horizontal
Logic stage goes negative .

Tektronix 7834 Specifications

General

Brand	Tektronix
Model	7834
Category	Test Equipment
Language	English