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Making Measurements Using Spectrum Analyzer Made
Using the Time-Gated Spectrum Analyzer Capability Without the Gate Utility (Option 107 only)
Use the guidelines in
7Able
5-l when using time-gated spectrum analyzer
capability to view a pulsed RF signal. These are only guidelines, and the
spectrum analyzer settings can be changed if necessary.
Table 5-1.
Determining Spectrum Analyzer Settings for Viewing a Pulsed RF Signal
Spectrum Analyzer
Function
Spectrum Analyzer Setting
Comments
Sweep Time
Set the sweep time to be 401 times greater Because the gate must be on at least once
than the pulse repetition interval
IPRII:
per trace point, the sweep time has to be
set to the pulse repetition interval times for
Sweep time
>
401 x
PRI
every point of the trace.
IEach
trace has
401 points.)
Gate Delay
The gate delay is equal to the signal delay The gate delay must be set so that the
plus half of the pulse width: gating captures the pulse. If the gate delay
is too short or too long, the gating can mist
Gate Delay = Signal Delay +
r/2
the pulse or include resolution bandwidth
transient responses.
Gate Length The gate length is equal to one-fourth the
If the gate length is too long, the signal
pulse width:
display can include transients caused by the
spectrum analyzer filters.
Gate length =
r/4
Video Bandwidth Set the video bandwidth to a value greater The video bandwidth must be wide enough
than 1 divided by the gate length: so that the rise times of the video
bandwidth do not attenuate the signal.
Video Bandwidth >
gate
,!englh
Resolution Bandwidth Set the resolution bandwidth to a value
The resolution bandwidth must be wide
greater then 2 divided by the gate delay
enough so that the charging time for the
minus the signal delay:
resolution bandwidth filters is less than the
pulse width of the signal.
Resolution Bandwidth >
2
Gate Delay
-
Signal Delay
5-39
-1