Delayedsweep Magnification

The delayed-sweep feature of the 2213A can be used to provide higher apparent magnification than is provided by the X10 Magnifier switch. Apparent magnification occurs as a result of displaying a selected portion of the trace (INTENS HORIZONTAL MODE) at a faster sweep speed (DLY'D HORIZONTAL MODE).

When INTENS HORIZONTAL MODE is selected, the intensified zone indicates both the location and the start of the sweep that will be displayed in DLY'D HORIZONTAL MODE. Positioning of the intensified zone (i.e., setting the amount of time between start of the sweep and start of the intensified zone) is accomplished with the MULTIPLIER control and the DELAY TIME Range Selector switch. At higher sweep speeds the delay time can be adjusted to allow the starting point of the intensified zone to occur past the end of the display.

With either INTENS or DLY'D HORIZONTAL MODE selected, the DELAY TIME Range Selector switch and the MULTIPLIER control provide continuously variable positioning of the start of the delayed sweep. The DELAY TIME Range Selector switch allows the start of the intensified zone to be placed near the point of interest, while the MULTIPLIER control provides fine adjustment of the intensified zone.

When viewing aperiodic signals (such as complex digital waveforms) with DLY'D HORIZONTAL MODE selected, the start of the sweep may not be at the same point as the start of the intensified zone. It may be necessary to connect a reference signal from the system under test to the EXT INPUT connector and to adjust VAR HOLDOFF control to ensure correct display of the selected portion of the waveform.

Using delayed-sweep magnification may produce a display with some slight horizontal movement (pulse jitter). Pulse jitter includes not only the inherent uncertainty of triggering the delayed sweep at exactly the same trigger point each time, but also jitter that may be present in the input signal.

The following procedure explains how to operate the delayed-sweep feature and to determine the resulting apparent magnification factor.

1. Preset instrument controls and obtain a baseline trace.

2. Apply the signal to either vertical channel input connector and set the VERTICAL MODE switch to display the channel used.

3. Set the appropriate VOLTS/DIV switch to produce a display of approximately 5 divisions in amplitude and center the display.

4. Set the SEC/DIV switch to a sweep speed which displays at least one complete waveform cycle.

5. Select INTENS HORIZONTAL MODE and set the DELAY TIME Range Selector switch for the appropriate delayed time. Adjust the MULTIPLIER control to position the start of the intensified zone to the portion of the display to be magnified.

NOTE

Since the Delay Ranges are overlapping and delay jitter is proportional to maximum delay of the range, always use the smallest delay range when in the overlapping areas.

EXAMPLE: If the delay required is 0.9 ms, use the 20 ms range (less than 100 ns jitter) instead of the 0.4 ms range (less than 2 fis jitter).

POINT OF INTEREST INTENSIFIED

TO BE MAGNIFIED ZONE

POINT OF INTEREST INTENSIFIED

TO BE MAGNIFIED ZONE

(B) MAGNIFIED TRACE c3397-21

Figure 4-10. Delayed-sweep magnification.

h. Set the generator output to produce a 1.5-division, 60-MHz display.

i. Repeat part d.

j. Move the generator output from the CH 2 OR Y input connector to the CH 1 OR X input connector. Set VERTICAL MODE to CH 1.

k. Repeat part d.

c. Set the leveled sine-wave generator to produce a 5-division, 50-kHz display.

VERTICAL MODE CH 2

SEC/DIV 0.2 MS

TRIGGER SOURCE EXT

e. Move the signal from the CH 1 OR X input connector to the EXT INPUT connector.

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