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OD-514B, OD-515B & OD-545B INSTRUCTION MANUAL
2.- COUPLING control [25] functions
This switch is used for selecting the coupling of the triggering signal to the trigger
circuit in accordance with the characteristics of the measured signal.
AC
HF REJ The triggering signal is fed to the trigger circuit through an AC coupling
TV
DC
November 2000
This coupling is for AC triggering which is used most commonly. As the
triggering signal is applied to the trigger circuit through an AC coupling
circuit, stable triggering can be attained without being affected by the DC
component of the input signal. The low-range cut off frequency is 10 Hz
(-3 dB). When the ALT trigger mode is used and the sweep speed is
slow, jitter may be produced. In such a case, use the DC mode.
circuit and a low pass filter (approximately 50 kHz, -3 dB). The higher
components of the trigger signal are rejected and only the lower
components are applied to the trigger circuit.
This coupling is for TV triggering, for observation of TV video signals. The
triggering signal is AC-coupled and fed through the triggering circuit (level
circuit) to the TV sync separator circuit. The separator circuit picks off the
sync signal, which is used to trigger the sweep. Thus, the video signal
can be displayed stably. Being linked to the TIME/DIV switch, the sweep
speed is switched for TV-V and TV-H as follows:
TV-V: 0.5 s - 0.1 ms
TV-H: 50 µs - 0.1 µs
The SLOPE switch [22] should be set to conform to the video signal as
shown in the following figure
The triggering signal is DC-coupled to the trigger circuit. This mode is
used when triggering is desired with the DC component of the triggering
signal or when a signal with very low frequency or a signal with large duty
cycle ratio is needed to be displayed.
Figure 11.-
Page 25
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