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C R T display
Hold-off time
0
Insufficient hold-off time
( 3 ) Optimum hold-off time
5. Adjust the S W E E P TIME/DIV control (§) to obtain an
appropriate display. Now a normal sweep display is ob-
tained.
[2] SWEEP magnification operation
Merely shortening the s w e e p time to magnify a portion of
observed waveform can result in the desired portion disap-
pearing off the screen, the desired portion can be displayed
without such trouble if the sweep magnification feature is
used (also refer to " S w e e p Magnification" on page 5 ) .
Using the < •
POSITION control, adjust the desired por-
tion of waveform to the C R T . Pull out the P U L L x 10 MAG
control to magnify the display 1 0 times. For this type of
display the sweep time is the S W E E P TIME/DIV setting
divided by 1 0 .
[3] X-Y operation
X - Y operation permits the oscilloscope to perform many
measurements
not
possible
operation.
Set the T R I G G E R MODE s w i t c h (g) to the X - Y position. In
this mode, channel 1 becomes the Y axis input and channel
2 becomes the X axis input.
The X and Y positions are now adjusted using the
POSITION @ and C H 1 • POSITION controls respectively.
X and Y sensitivity are set by using the channel 2 and chan-
nel 1 V A R I A B L E V O L T S / D I V controls respectively.
[41 VIDEO signal observation
Setting the COUPLING (§) s w i t c h , to the T V F R A M E or T V
LINE position permits selection of vertical or
sync pulses for s w e e p triggering when viewing composite
video waveforms.
This makes stable triggering in video signal observations
possible regardless of the T R I G L E V E L control (£j) .
A t most points of measurement, a composite video signal
is of the polarity, that is, the sync pulses are negative and
the video is positive. In this case, use " — " S L O P E .
If the waveform is taken at a circuit point where the video
waveform is inverted, the s y n c pulses are positive and the
video is negative. In this case, use " + " S L O P E .
16
(2) Insufficient hold-off time
with
conventional
sweep
•
horizontal
[B] EQUIVALENT SAMPLING
The equivalent sampling mode is activated automatically
when the S W E E P T I M E / D I V control ' f |
between 0 . 1 /xs/div and 1 0 /*s/div. When the mode is
swtiched from the real-time mode to equivalent sampling
mode, the
bandwidth
is also switched from 4 0 MHz
( - 3 dB) to
1 0 0 MHz
( - 3 dB)
amplitude may vary with higher input signal frequencies.
When it is required to observe amplitude variations, fix the
mode either to the real-time or equivalent sampling mode.
With a sampling oscilloscope, different parts of the input
signal are sampled with certain time differences, and the
signals obtrained are amplified and applied to the vertical
amplifier. A t the same time, the time signals corresponding
to the sampling time difference are applied to the horizontal
amplifier, so that the same image a s the input signal is re-
constructed on the display using the t w o types of signals.
This s y s t e m therefore necessitates that the input signal is a
repetitive waveform, and the repetitions shall continue for
a certain period and shall be stable.
Input
Sampling
pulse
Output
Fig. 10 s h o w s a case in which a sampling pulse that is
delayed by a specified period from the input signal is
generated, and the signal held by the sampling pulse
becomes the output signal.
In the example s h o w n in this figure, the output signal S Y N C
is 1/12 of the input signal.
NOTE:
When the input signal frequency is low, the dots
of the waveform observed by equivalent sampling
become coarse.
If triggering is applied incorrectly, the equivalent
sampling operation will be abnormal, so that the
displayed waveform will be totally different from
the real input signal.
is set to the range
so
that
the
display
Fig. 10
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