Tektronix 7853A, Instruction Manual

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Operating lnstructions-~7B53A/7B53AN Operators
Triggered Delayed Sweep Magnification
The delayed sweep magnification method just described
may produce too much jitter at high apparent magnifica­
tion ranges. The Triggered Delayed Sweep Mode (DLY'D
TRIG LEVEL control rotated out of switch detent)
provides a more stable display, since the delayed sweep
display is triggered at the same point each time.
1. Set up the display as instructed in steps 1 through 7
in the Delayed Sweep Magnification procedure.
2. Rotate the DLY'D TRIG LEVEL control in a
counterclockwise direction but out of switch detent for a
triggerable delayed sweep. Select the desired DLY'D TRIG
SLOPE, COUPLING, and SOURCE.
3. Adjust the DLY'D TRIG LEVEL control to produce
an intensified portion on the display.
Use the following procedure:
1. Set up the display as given in Steps 1 through 8 of
Delayed Sweep Magnification.
2. Time measurements can be made from the display in
the conventional manner. Sweep rate is determined by the
setting of the DLY'D Time/Division switch.
Example. Fig. 1-17 shows a complex waveform as
displayed on the CRT. The circled portion of the waveform
cannot be viewed in any greater detail because the sweep is
triggered by the larger amplitude pulses at the start of the
display and a faster sweep rate moves this area of the
waveform off the viewing area. The second waveform shows
the
area of interest magnified 10 times using Delayed
Sweep. The DELAY TIME MULT dial has been adjusted so
the delayed sweep starts just before the area of interest.
4. Inability to produce an intensified portion on the
display indicates that the DLY'D TRIG controls are
incorrectly set, or that the signal does not meet triggering
requirements. If the condition cannot be remedied with the
DLY'D TRIG controls or by increasing the display ampli­
tude (lower Volts/Division setting), externally trigger the
delayed sweep.
5. When the correct portion of the display is intensified,
press in the DLY'D Time/Division switch for the DLY'D
SWP Display Mode, slight readjustment of the DLY'D
TRIG LEVEL control may be necessary to produce a stable
delayed sweep display.
6. Measurement and magnification are as described
above in Delayed Sweep Magnification discussion.
Displaying Complex Signals Using Delayed Sweep
Complex signals often consist of a number of individual
events of differing amplitudes. Since the trigger circuits are
sensitive to changes in signal amplitude, a stable display can
normally be obtained only when the sweep is triggered by
the event(s) having the greatest amplitude. However, this
may not produce the desired display of a lower-amplitude
portion which follows the triggering event. The delayed
sweep feature provides a means of delaying the start of the
delayed sweep by a selected time following the event which
triggers the main sweep generator. Then, the part of the
waveform which contains the information of interest can be
displayed at the delayed sweep rate.
Fig. 1-17. Displaying a complex signal using delayed sweep.
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