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Triggered B Sweep.
In
basic delayed sweep, the B timebase is not triggered by
a signal event, it begins when the main (A timebase) sweep cross comparate level setting
by DLY TIME
pas.
knob. The only problem with this is that main timebase jitter
becomes appearent in the B sweep at high ratios of A to B TIME/DIV switch settings
(100 : 1 and up). To circumvent this, the B sweep can be triggered by the signal itself,
or a time-relate trigger signal. The DELAY TIME
pas
control then determines the
minimum delay time between A and B sweeps; the actual delay time will be that plus
the additional time until the next available trigger. The result is that actual delay time
is variable only with step resolution, in increments of the interval between triggers.
The maximum magnification possible by this technique is several thousand times. CRT
brightness being the limiting factor.
For triggered B sweep, proceed as follows
1. Set up the scope for basic delayed sweep as described
in the preceding
paragraphs.
2. Press in the B TRIG'D pushbutton (23), and adjust the Trigger LEVEL control (34)
if necessary. The B time base is now triggering on the same trigger singal as
the A timbase. The start of B sweep will always be a leading or trailing
edge of the trigger signal ; truning the DELAY TIME
pas
control will not change
this.
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