Specifications

142 Chapter 15
Concepts
Time Gating Concepts
Concepts
Figure 15-15 Time-domain Parameters
In Figure 15-15, the parameters are:
• Pulse repetition interval (PRI) is 5 ms.
• Pulse width (
τ) is 3 ms.
• Signal delay (SD) is 1 ms for positive edge trigger (0.8 ms for
negative edge trigger).
• Gate delay (D) is 2.5 ms.
• Setup time (SUT) is 1.5 ms.
Step 2. Set the spectrum analyzer sweep time:
PSA: Sweep time does not affect the results of gated LO unless the
sweep time is set too fast. In the event the sweep time is set too fast,
Meas Uncal appears on the screen and the sweep time will need to be
increased.
ESA: Sweep time does affect the results from gated video. The sweep
time must be set accordingly for correct time gating results. The sweep
time should be set to at least the number of sweep points - 1 multiplied
by the PRI (pulse repetition interval).
Step 3. Locate the signal under test on the display of the spectrum analyzer.
Set the center frequency and span to view the signal characteristics
that you are interested in measuring. Although the analyzer is not yet
configured for correct gated measurements, you will want to determine
the approximate frequency and span in which to display the signal of
interest. If the signal is erratic or intermittent, you may want to hold
the maximum value of the signal with
Max Hold (located under the