GW Instek GOS-652G - Manual (Page 26)

⎯ 21 ⎯
The above triggering source signal selection functions are shown collectively in the following table.
VERT.MODE
SOURCE
CH1 CH2 DUAL ADD
CH1 Triggered by CH1 signal
CH2 Triggered by CH2 signal
ALT Alternately triggered by CH1 & CH2
LINE Trigged by LINE signal
EXT Trigged by EXT TRIG input signal
(2) Functions of COUPLING switch:
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 : 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 10Hz (-3dB).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.
HF REJ : The triggering signal is fed to the trigger circuit through an AC coupling circuit and a low pass filter (approximately
50kHz,-3dB). The higher components of the trigger signal are rejected and only the lower components are applied to the
trigger circuit.
TV : 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 Figure 4-8
TV-H : 50
µs - 0.1 µs
The SLOPE switch should be set to conform to the video signal as shown in Figure 4-8.
DC : 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.