In many data analyses, the trigger times may be ignored, especially if
relative time measurements are made. In INTERLEAVED acquisition,
however, ignoring the trigger times results in the interleaved sweeps
being put on an equidistant timing grid, although they are not
necessarily equidistant at acquisition. This is equivalent to
introducing an acquisition jitter of up to 0.~ nominal sampling
interval, i.e. degrading the (apparent) dynamic behavior of the ADC.
7.9
Data Addressing Conventions
Data values are always addressed in a screen-oriented manner. Address 0
always corresponds to the data value at the left hand edge of the
display screen. Although the 9400A always digitizes 32000 points
(except in interleaved sampling or in SEQNCE mode), it is not possible
to display all of them on the screen, because of the ratio TIME/DIV to
sampling interval. Points which are inaccessible on the screen are
always positioned to the LEFT of the display screen, and can be read by
remote control (using negative address values).
Examples:
(a)
At 0.5 msec/div, a sampling interval of 200 nsec is used, which
covers a total time of 32000 * 200 nsec = 6.4 msec. However, only
10 * 0.5 msec = 5 msec can be shown on the screen. Thus, only
25000 out of 32000 acquired points are shown. The other 7000
points cannot be displayed on the screen, but are accessible by
remote control with the READ command (using negative addresses).
.5 ms/div
left edge
of screen
I
I I
-7000 0
250OO
displayed record, 2500Opts, 5ms
digitized record, 3200Opts, 6.4 ms
(b)
At 5 ~sec/div, a sampling interval of i0 nsec is used, covering a
total time of 32000 * 10 nsec = 320 usec. However, only
10 * 5 usec = 50 usec can be shown on the screen at this time-base
setting. Only 5000 out of 32000 acquired points are shown. The
other 27000 values are not displayed, but are accessible by remote
control.
7-48
Remote Operations
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