Quick Rules" For Making Time-Gated Measurements - Keysight X Series Measurement Manual

Concepts
Time Gating Concepts

"Quick Rules" for making time-gated measurements

This section summarizes the rules described in the previous sections.
Table 15-1 Determining Signal Analyzer Settings for Viewing a Pulsed RF Signal
Signal Analyzer Signal Analyzer Setting
Function
Sweep Time Set the sweep time to be equal to or
(gated video greater than
only)
(number of sweep points - 1) ×
pulse repetition interval (PRI):
Gate Delay The gate delay is equal to the signal
delay plus one-fourth the pulse
width:
Gate Delay = Signal Delay + τ/5
Gate Length The gate length minimum is equal
to one-fourth the pulse width
(maximum about one-half):
Gate Length = 0.7 x τ/4
Resolution Set the resolution bandwidth:
Bandwidth
RBW > 19.5/τ
Figure 15-21 Gate Positioning Parameters
Comments
Because the gate must be on at least once
per trace point, the sweep time should be set
such that the sweep time for each trace point
is greater than or equal to the pulse repetition
interval.
The gate delay must be set so that the gating
captures the pulse. If the gate delay is too
short or too long, the gating can miss the
pulse or include resolution bandwidth
transient responses.
If the gate length is too long, the signal
display can include transients caused by the
signal analyzer filters.
The recommendation for gate placement can
be between 20 % to 90 % of the pulse width.
The resolution bandwidth must be wide
enough so that the charging time for the
resolution bandwidth filters is less than the
pulse width of the signal.
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