Tektronix 7B80 Instruction Manual page 87

Option
2—
7B80
3.
The
attenuator switch of the
vertical
channel
in
the
hori-
zontal
signal
path provides
many
deflection-factor
settings
to
allow
full-range
amplitude
control.
3.
Set each
amplifier unit input
coupling switch
to dc,
and
set
the position controls of the
selected
X
and
Y
channels
for
a
spot display
at graticule center.
OPERATION WITH DUAL-TRACE
AMPLIFIERS. When
dual-trace amplifier units are based with the Option
2
Time-
Base
unit,
any
vertical
channel
may
be used
for
X
or
Y
signal inputs.
Set the display
mode
controls of both the
amplifier and mainframe
to
select
the channel that provides
the
vertical signal; set the
trigger
source controls of
both
the amplifier and mainframe
to
select
the channel that
pro-
vides the horizontal
signal.
OPERATION WITH
SINGLE-TRACE
AMPLIFIERS.
If
single-trace amplifier units
are
used with the Option
2
Time-Base
unit, set
the
mainframe
trigger
source control
to
select
the amplifier
unit that
provides the horizontal
signal;
set
the mainframe
vertical
mode
control to
select the ampli-
fier
unit that provides the
vertical signal.
4.
Connect
low-frequency
sine-wave
signals of the
same
frequency
to the
selected
X
and
Y
inputs.
5.
Advance
the mainframe
intensity control
until
the
dis-
play
is
at
the desired viewing
level.
Set the amplifier
deflec-
tion factors
and
variable volts/division
controls for eight
divisions of
vertical
and
horizontal deflection,
and
set
the
position controls to center the display
on
the
graticule as
shown
in
Figure
2.
6.
Measure and
record the
overall horizontal deflection
(B)
and
the opening
of the
Lissajous display
(A),
measuring
horizontally
at
the
graticule horizontal center
line (see
Figure
2).
APPLICATIONS
The
following information describes
a
procedure
or tech-
nique
for
making
X-Y
phase measurements
with the Option
2 Time-Base
unit.
The measurements
are described
in a
de-
tailed
example,
but each
user application
must
be adapted
to the requirements
of the individual measurement. The
following
X-Y
phase
measurement method
can be used to
measure
the phase angle between two
signals
of the
same
frequency.
Preliminary Setup
1
.
Set the
DISPLAY
MODE
push button
to
the
OUT
:
X-Y
position.
Set the mainframe
intensity control
for conven-
ient brightness of the spot display.
2.
Set the controls of the
mainframe and
the amplifier
units
as
directed
in
the following setup
procedure
for
the
amplifier units to be used.
DUAL-TRACE
AMPLIFIERS.
Set the
vertical display
mode
controls of both the amplifier
and mainframe
to
select the input of the
Y
(vertical) signal; set the
trigger
source controls of
both
the amplifier
and mainframe
to
select
the input of the
X
(horizontal)
signal.
SINGLE-TRACE
AMPLIFIERS.
Set the
vertical display
mode
control of the mainframe
to select the input of the
Y
(vertical) signal; set the
trigger source control of the
mainframe
to
select
the input of the
X
(horizontal)
signal.
7.
Divide
A
by
B
to obtain the trigonometric
sine
of the
phase angle difference between
the
two
signals.
Obtain
the
phase
angle
from
a
trigonometric
table to determine the
phase
angle between
the
X
and
Y
signals.
Example: Assume
that the horizontal distance
measured
at
the center
opening
of the display (A)
is
2.7 divisions
(see
Figure
2.
Measurement
of phase angle difference
from
an
X-Y
display.
@
Option
2—
Page 3