Elenco 30MHz Dual Trace - Manual (Page 46)

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OPERATING INSTRUCTIONS
Trigger SOURCE Switch
The trigger SOURCE switch (CH 1, CH 2, etc.) selects the signal to be used as the
sync trigger.
1. If the SOURCE switch is set to CH 1 (CH 2) the channel 1 (or channel 2) signal
becomes the trigger source regardless of the VERTICAL MODE selection. CH 1,
or CH2 are often used as the trigger source for phase or timing comparison
measurements.
2. By setting the SOURCE switch to ALT, alternation triggering mode is activated. In
this mode, the trigger source alternates between CH 1 and CH 2 with each sweep.
This is convenient for checking amplitudes, wave shape, or waveform period
measurements, and even permits simultaneous observation of two waveforms
which are not related in frequency period. However, this setting is not suitable for
phase or timing comparison measurements. For such measurements, both traces
must be triggered by the same sync signal. Alternate triggering can only be used in
dual-trace mode (VERT MODE set to DUAL), and with alternate sweep only
(PULL CHOP not engaged).
3. In the EXT position of the COUPLING switch, the signal applied to the EXT TRIG
jack becomes the trigger source. This signal must have a timing relationship to the
displayed waveforms for a synchronized display.
4. In the LINE position of the COUPLING switch triggering is derived from the input
line voltage (50/60 Hz) and the trigger SOURCE switch is disabled. This is useful
for measurements that are related to line frequency.
TRIG LEVER Control
The TRIG LEVEL control adjusts the start of the sweep to almost any desired point on
a waveform. On sine wave signals, the phase at which sweep begins is variable
toward its extreme + or - setting, no sweep will be developed in the normal trigger
mode because the triggering threshold exceeds the peak amplitude of the sync
signal.
SLOP Switch
This switch selects the slope (polarity) of the
triggering signal.
Push down the switch to be set in the “+” state,
triggering occurs as the triggering signal crosses
the triggering level in the direction of signal
increase (i.e, positive direction).
Pull up the switch to be set in the “-“ state, triggering occurs as triggering signal
crosses the triggering level in the direction of signal decrease(i.e, negative
direction).
+
-
Po s it iv e-gin g
slo pe
N ega t iv e-gin g
slo pe