Important Concepts
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Main delay and gate delays are independant for each channel—you can select
different delay times for both main and gate regions for each channel—though
lengths must be the same for both channels.
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You can smoothly scroll with the knob to change data position and length.
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You can use averaging on gated measurements. Rms and peak averaging are
applied to the spectrum display of the gate, while time averaging is applied to
the main time record.
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You can step the gate delay through the main time data in predetermined
increments by setting [
step size
] to the desired increment, then selecting [
gate delay
]
and using the up and down arrow keys.
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In some applications the overhead required to acquire a new main record may
be undesirable. In this case you may expand the gate region to cover the entire
display with the [
gate->main
] key. You may then continue to analyze the previous
gate region without collecting a large main record.
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The maximum length of the main record is determined by the span and the
number of frequency points. When working in the time domain you may not
want to be limited by the selected span. In this case you would like the span to
be adjusted to meet your main record length needs. To do this you can set [
time
resltn
] to [
auto
] then you may adjust main length while span is automatically
adjusted to keep the number of points in the main record within the limits of
the maximum number of frequency points in memory.
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You can increase the main record length by increasing the number of
frequency points. You will then be able to select a narrower resolution
bandwidth, longer time length, or wider frequency span.
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Resolution bandwidth cannot be independantly adjusted in time gating
because the resolution bandwidth is determined by the length of the time
record. Since you set the length of the time record in gated measurements, you
cannot set resolution bandwidth.
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If you are using gating to estimate the frequency or phase of a signal at a
specific point in time you may want to consider using demodulation instead.
With demodulation you can measure the instantaneous frequency or phase at a
point in time, rather the estimate over the gate interval.
Gating Concepts
21 - 5
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