Thumbtacks And Cursor; Rubber Band Editing; Inserting Standard Waveforms; Digital Amplitude - Wavetek 75 Instruction Manual

2. Setting the Z-axis voltage level.
The Z-axis output has a fixed low level of approxi-
mately 0.2 volts and a high level that is adjustable
to approximately 2,4,6,8,10,12, or 14 volts. If your
oscilloscope can be damaged by any of these Z-axis
output levels, be sure that you do not exceed the
maximum for your oscilloscope. This output can be
loaded with a 50Q feedthrough termination to reduce
these levels by approximately a factor of 10.
Set the timebase on the oscilloscope to show one
or more waveform periods, then use the following
procedure to adjust the Z-axis output and
oscilloscope intensity for best viewing.
a. With no feedthrough termination, set the Z-axis
level to 2 volts using the ZLEVL soft key (from
the Setup menu). Connect the Z-axisoutput
cable to the oscilloscope.
b. Adjust the oscilloscope intensity to the desired
brightness.
c. If the contrast between the bright dots (thumb-
tacks and cursor) and the rest of the waveform
is too high, add a 50R feedthrough termination
and return to step b. Alternately adjust the
ZLEVL and oscilloscope intensity until the
brightness and contrast are as desired.
3.6 THUMBTACKS AND CURSOR
Most of the waveform editing features use "thumbtacks"
for defining the portion of the waveform to be edited. The
thumbtacks are marked by pulses on the Z-axis output
and therefore show up as bright dots on an oscilloscope
waveform if Z-axis modulation is used. The position of
the thumbtacks is adjusted by using the L,RTT soft key
from the Edit menu. Pressing this soft key the first time
enables adjustment of the left thumbtack (lower address)
with the Control knob. Pressing the soft key additional
times alternates between enabling adjustment of the
right thumbtack and the left thumbtack. Acursor is used
for "point" and "rubber band" editing. The position of
the cursor can be adjusted by selecting the CSR soft key
(from the Edit menu). The cursor isalso marked bya pulse
on the Z-axis output and will show up as a bright dot on
the oscilloscooe display.
3.7 RUBBER BAND EDITING
"Rubber band" editing is analogous to stretching a
rubber band fromone thumbtack, to the cursor, and then
to a second thumbtack. To use this editing method, place
the left and right thumbtackson each side of the portion
of the waveform to be edited (use L,RTT), then use the
ADJX,Y soft key and Control knob to move the vertex
either in the X (horizontal) or Y (vertical) direction. The
CSR soft key can be used to pre-position the cursor
(without changing the waveform) before using the
ADJX,Y function. This is useful for editing the waveform
while the Model 75 is connected to a system under test.
3-8
3.8 INSERTING STANDARD WAVEFORMS
Standard waveforms (sine, cosine, haversine, inverse
sine, triangle, square, ramp up, ramp down, dc) are
inserted between the thumbtacks using the FUNC soft
key (from the Edit menu). When a standard waveform
is inserted, it will be at full amplitude (as set by AMPL
parameter) and centered around the offset voltage (as
set by the OFFSET parameter). The relative amplitude
and offset can be adjusted using "DAMPL" and "DOFF"
as described in paragraphs 3.9 and 3.1 1. To insert a
standard waveform:
1. Set the desired end points using the L,RTT soft key
(from the Edit menu).
2. Press the FUNC soft key (from the Edit menu) and
use the Control knob to select thedesired waveform
3. Press the EXEC soft key to insert the waveform.
4. Use "DAMPL" and "DOFF" as described in
paragraphs 3.9 and 3.1 1 to change the relative
amplitude and offset of the inserted waveform if
necessary.
3.9 DIGITAL AMPLITUDE
The "Digital Amplitude" editing feature allows adjust-
ment of the amplitude of a portion of the waveform
relative to the rest of the waveform. The waveform con-
sistsof a 4095point high windowwith anamplitude con-
trolled by the "AMPL" parameter. The "DAMPL" editing
feature adjusts the amplitude of a portion of the
waveform relative to this window. The change in
amplitude is referenced to the left thumbtack as the zero
point. The digital amplitude feature is not available in
chained operation (waveforms longer than 2048 hori-
zontal points). To use digital amplitude, set the end points
of the section to be edited using the L,RTTsoft key(from
the Edit menu), press the DAMPLsoft key, and then use
the Control knob to adjust the amplitude. The digital
amplitude can be adjusted past zero to negative
amplitude to invert a portion of the waveform.
3.1 0 NORMALIZING
Pressing the "NORML" soft key from the "EDIT" menu,
scales the portion of the waveform between the thumb-
tacks such that the peak value will be
+
2047 or
-
2047
points. This is equivalent to adjusting the digital
amplitude to full scale.
3.1 1 DIGITAL OFFSET
"Digital Offset" is similar todigital amplitude, but is used
to adjust the offset of a portion of the waveform relative
to the rest of the waveform. To use digital offset, set the
left and right thumbtacks (L,RTT soft key from the Edit
menu) to the ends of the portion to be offset, press the
DOFF soft key, and then use the Control knob to adjust
the offset. When adjusting the digital offset, the Z-axis
output is turned off toenable more accurate adjustment
when viewing on an oscilloscope.
Scans by ArtekMedia O 2006