Wavetek 182A Instruction Manual page 12

3.2.3
Voltage Controlled Function Generator
Operation
Operation as a voltage controlled function
generator
(VCG)
is
as
for
a
manually
controlled function
generator, only the
frequency
within particular
ranges
is
additionally controlled
by an external voltage
(
± 4V
excursions) injected at the
VCG
IN
connector.
Per-
form
the steps given
in
paragraph
3.2.2,
only set the
frequency
dial to
determine a
reference
from which
the
frequency
is
to
be voltage controlled.
four
times
the multiplier setting,
and
the
lower
limit is 1/1
000th of the upper
limit.
+ 5V
;
-j-jr
—JUL-
_
5V
ol_
DC
OFFSET
*"W
A
A
vv
POSITIVE
DC OFFSET
JYV_
NEGATIVE
DC OFFSET
+5V
1X1X1
A
A
'VV
-5V
—
EXCESSIVE
POSITIVE
OFFSET OR
LOADING
Ml
EXCESSIVE
NEGATIVE
OFFSET
OR
LOADING
Figure 3-3.
DC OFFSET
Control
1
For frequency control with positive dc inputs
at
VCG
IN,
set the
dial for
a lower frequency
limit.
2.
For frequency
control with
negative
dc
inputs at
VCG
IN, set
the
dial for
an upper frequency
limit.
3.
For modulation with
an ac
input
at
VCG
IN,
set
the dial at
the desired center frequency.
Do
not
exceed
the
maximum
dial
range of the selected
frequency range.
Figure
3-4
is
a
nomograph
with
examples
of dial
and
voltage
effects.
Example
1
shows
that with
OV
VCG
in-
put,
frequency
is
determined by
the
main
dial setting,
2
in
this
example.
Example
2
shows
that
with a
positive
VCG
input,
output frequency
is
Increased. Ex-
ample 3
shows
that with
a negative
VCG
input,
output
frequency
is
decreased. (Note
that the
Output
Fre-
quency Factor
column
value must be
multiplied
by
a
frequency range
multiplier to give the actual output
frequency.)
NOTE
Nonlinear operation
may
result
when
the
VCG
input voltage
is
excessive; that
is.
when
the
attempted generator frequency
exceeds
the
range
limits.
The upper
limit
is
OUTPUT
MAIN
DIAL
VCG
IN
FREQUENCY
SETTING
VOLTAGE FACTOR
4
-
-4-|
-3-
-2-
-1-
-.004
3-
'*#*£-*
-1
-1.5
2
-
^
0-
EXAMPLE
1
-2.0
\
1-
-
2.5
1 - 2.0-
3.0-
.
%
-
-3.0
-3.5
.004
.
4.0-
X
-4.0
Figure
3-4.
VCG
Voltage-to-Frequency
Nomograph
The up
to
1000:1
VCG
sweep
of
the generator
fre-
quencies
available
in
each
range
results
from a
4V
ex-
cursion
at
the
VCG
IN
connector. With the frequency
dial
set
to 4.0,
excursions
between
—
4V
and
0V
at
VCG
IN provide the
up
to 1000:1
frequency sweep.
With the
dial
set to .004,
excursions
between 0V and
+
4V
at
VCG
IN provide the
up
to
1
000:1
sweep
within
the set
frequency
range.
3.2.4
Waveforms
See
figure 3-5 for definition of controllable
waveform
characteristics.
(1/f)
OVdc
PERIOD
1
AMPLITUDE
OFFSET
~~
""
~~
_]_
sine^AAAAAA/V
CONTINUOUS
1
.
A A A
.
A
A
'
M DE
<JTRIANGLEVV\/VV\/\/V
SQUARE^l^m^I
sync
T_njn_n_n_n_rL_rLr
TRIG
IN-
~rz2_
sine^VW
V
s
GATED
J
.
. .
.
.
MODE
^TRIANGLE
VW
LA
8QUARE
_
lJ
_
Lru
Ul
Figure
3-5.
Waveform
Characteristics
3-3