Keysight Technologies N5171B EXG, Руководство пользователя

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218 Keysight EXG and MXG X-Series Signal Generators User’s Guide
Basic Digital Operation (Option 653/655/656/657)
Using Waveform Markers
Using the EVENT Output Signal as an Instrument Trigger
One of the uses for the EVENT output
signal (marker signal) is to trigger a
measurement instrument. You can set
up the markers to start the
measurement at the beginning of the
waveform, at any single point in the
waveform, or on multiple points in the
waveform. To optimize the use of the
EVENT signal for measurements, you
may also need to adjust the sample
rate. The location of the sample rate setting is shown in the figure at right.
The EVENT output signal can exhibit jitter of up to ±4 ns on the rising and falling edge. This jitter
can be minimized in either of two ways.
Method 1 : Use a sample clock of 125 MHz/N where N is a positive integer and where 125 MHz/N
can be represented exactly on the display.
For example: 125 MHz, 62.5 MHz, 31.25 MHz, 25 MHz, and so on.
If the result cannot be represented exactly on the display, jitter will be present.
For example: N = 6 will result in jitter, because 125 MHz/6 = 20.833 Mhz, which is truncated when
displayed.
Method 2 : Select a sample clock and waveform length that spaces the markers by a multiple of 8
ns. For example: A 200 point waveform with a marker on the first point and a sample clock of 50
MHz provides a marker every 4 µs. Because 4 µs is a multiple of 8 ns, the jitter is minimized.
When the EVENT output signal exhibits jitter and it is used as a measurement trigger, it can cause
the waveform to falsely appear as having jitter. If this condition occurs, you can adjust the sample
rate to a value (see above) that does not cause the jitter appearance. To maintain the integrity of
the original waveform with a sample rate change, you will have to also recalculate the sample
values. The following figures illustrate the marker signal jitter and its affect on the waveform.
Sample
rate
setting
The settings in this menu
can be stored to the file
header, see
page 197
.
For details on each key, use key help as described on
page 40
.
The jitter is gone with
an optimal sample rate Waveform appears to exhibit jitter when
triggered using EVENT signal with jitter.
Oscilloscope triggering on waveform Oscilloscope triggering on EVENT signal
Oscilloscope triggering on EVENT signal
EVENT output signal exhibits jitter
due to a non–optimal sample rate