Performance Tests Model 8904A
AMPTD
1
V
f2
(Continuous)
NEXT
NEXT
f2
(On
Time)
3.
Adjust the oscilloscope’s vertical gain
and
sweep speed to view the
1
kHz output burst from the
Multifunction Synthesizer. The waveform should appear similar to the one shown in Figure 4-10.
NOTE
The
waueform shown was triggered on
a
negative-going zero crossing. If
the
oscilloscope
is
difiult to trigger, try adjusting
the
sweep
time
so
that
only
one tone burst shows. Sweep
time
is
not
critical.
Also
try
“normal”
triggering
(as
opposed
to
“automatic” triggering). If fewer
than
fourteen zero-crossings
of
the
burst show,
the
display
is
still
valid
unless
the
waueform
is
unstable.
4.
On the Multifunction Synthesizer, press the
0
or
U
keys until the negative-going zero crossing
of
the last cycle
of
the tone burst touches
OV
with no positive
or
negative slewing. (Slewing refers
to
the rapid change in voltage which appears
as
a vertical line
on
the oscilloscope.) The
“On
Time”
setting which appears on the Multifunction Synthesizer’s display should be between 4.27
and
6.27
ms.
On-Time Timing:
4.27
6.27
ms
Off-Time
Accuracy
5.
On the oscilloscope adjust the sweep time and position so that the time between the first and
second burst (the off-time)
can
be measured. The off-time should be between 9 and
11
ms.
Off-Time Timing:
9
11
ms
Figure
4-10.
DTMF
Burst
Wweform with Slight Negative
Skwing
4-42
Performance Test
13
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