GW Instek GOS-652G - Manual (Page 25)

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EXT HOR(external sweep) Operation
The external signal applied through the EXT HOR terminal(23) drives the X-axis. The Y-axis is with any channels as selected
by the VERT MODE switch. When the DUAL mode is selected by the switch, both CH 1 and CH 2 signals are displayed in the CHOP
mode.
4.7 Triggering
Proper triggering is essential for efficient operation of an oscilloscope. The user must be thoroughly familiar with the triggering
functions and procedures.
(1)Functions of SOURCE switch:
The displayed signal itself or a trigger signal which has a time relationship with the displayed signal is required to be applied to
the trigger circuit to display a stationary signal on the CRT screen. The SOURCE switch is used for selecting such a triggering
source.
CH 1 : The internal trigger method which is used most commonly.
CH 2 : The signal applied to the vertical input terminal is branched off from the preamplifier and is fed to the trigger circuit
through the VERT MODE switch. Since the triggering 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 signal selected by the
SOURCE switch is used as the triggering source signal.
LINE : The AC power line frequency signal is used as the triggering 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 with an external signal applied to the external trigger input terminal. An external signal which
has a periodic relationship with respect to the measured signal is used. Since the measured signal is not used as the
triggering signal, the waveforms can be displayed more independent than the measured signal.