Figure 2-61 . Time-Gated Spectrum Of Signal Number 2 - Agilent Technologies 8560E User Manual

Making Measurements
Example 11: Time-Gated Measurement
Figure 2-61 Time-Gated Spectrum of Signal Number 2
Time-gating lets you define a time window, or time gate, during which a
measurement will be performed. This permits you to specify the part of
a signal that you want to measure, and exclude or mask out other
signals that might interfere.
How Time-Gating Works
Time-gating is achieved because the spectrum analyzer selectively
interrupts the path of the detected signal, as shown in Figure 2-62. By
opening and closing a switch relative to an externally supplied trigger
signal, the analyzer controls the times at which it captures
measurement data. Under the right conditions, the only signals that
the analyzer measures are those present at the input to the analyzer
when the gate is on. With the correct spectrum analyzer settings, all
other signals are masked out.
The RF section of the spectrum analyzer is responding to the full signal.
The selective gating occurs only before the video processing. This means
that there are some limitations on the gate settings because of signal
response times in the RF signal path.
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