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TV-H Set the MODE switch to TV-H mode and select horizontal sync pulses for sweep triggering to view
composite video waveforms. Select horizontal sync pulses as a triggering to view horizontal lines of
video. A sweep time of about 10 us/div is appropriate for displaying lines of video. Display the exact
number of desired waveforms by setting SWP VAR control knob.
This oscilloscope synchronizes with only (-) polarity, that is, the sync pulses are negative and the video
is positive as shown in Fig. 5-3.
Fig. 5-3
(2)Functions of SOURCE switch:
Apply the displayed signal itself or a trigger signal, which has a time relationship with the displayed signal, to the
trigger circuit to display a stationary signal on the CRT screen. The SOURCE switch is used for selecting these
trigger sources.
CH1 The internal trigger source is used most commonly.
CH2 The signal applied to the vertical input terminal is branched off away from the preamplifier and is fed to
the trigger circuit through the VERT MODE switch. Since the trigger signal is the measured signal itself,
a stable waveform can be readily displayed on the CRT screen. When in the DUAL or ADD operation,
the selected signal through the SOURCE switch is used as a trigger source signal.
LINE The AC power line frequency signal is used as a trigger signal. This method is effective when the
measured signal has a relationship with the AC line frequency, especially for measurements of low level
AC noise of audio equipment, thyristor circuits, etc.
EXT The sweep is triggered by an external signal applied to the external trigger input terminal. An external
signal which has a periodic relationship with the measured signal is used. Because the measured signal
is not used as the triggering signal, the waveforms can be displayed more independent than the
measured signal.
(3)Functions of TRIG LEVEL control knob and SLOPE button:
A sweep triggering is developed when the trigger source signal crosses a preset threshold level. Rotate TRIG LEVEL
control knob to vary the threshold level. In the “+” direction, the trigger threshold shifts to a more positive value, and in
the “-“ direction, the trigger threshold shifts to a more negative value. When set the control knob in the center, the
threshold level will be on the average of the signal used as the trigger source.
Adjust TRIG LEVEL control knob for the desired start point of sweep on a waveform. On sine wave signals, the phase at
which sweep begins is variable. Note that if rotate TRIG LEVEL control knob toward its extreme “+” or “-”, no sweep
will be developed in the NORM trigger mode because the trigger threshold exceeds the peak amplitude of the sync
signal.
When set TRIG SLOPE button to the (+) position (up), the sweep is developed form the trigger source waveform as it
crosses the threshold level in a positive-going direction. When set TRIG SLOPE button to the (-) position (down), a
sweep triggering is developed from the trigger source waveform as it crosses the threshold level in a negative-going
direction. The slope (polarity) trigger signal as shown in Figure 5-4.
Fig. 5-4
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