Specifications

150 Chapter 15
Concepts
Time Gating Concepts
Concepts
Erratic analyzer trace with
dropouts that are not
removed by increasing
analyzer sweep time;
oscilloscope view of gate
output signal jumps
erratically in time domain.
Gate Delay may be greater
than trigger repetition
interval.
Reduce Gate Delay until it
is less than trigger interval.
For PSA check
Gate View to
make sure the gate delay is
timed properly.
Gate does not trigger. 1) Gate trigger voltage may
be too low.
2) Gate may not be
activated.
3) (PSA)
Gate Source
selection may be wrong.
Ensure gate trigger reaches
TTL levels. Check to see if
other connections to trigger
signal may be reducing
voltage. If using an
oscilloscope, check that all
inputs are high impedance,
not 50
Ω.
Display spectrum does not
change when the gate is
turned on.
Insufficient setup time. Increase setup time for the
current resolution
bandwidth, or increase
resolution bandwidth.
Displayed spectrum too low
in amplitude.
Resolution bandwidth or
video bandwidth filters not
charging fully.
Widen resolution
bandwidth or video
bandwidth, or both.
Table 15-4 If You Have a Problem with the Time-Gated Measurement
Symptom Possible Causes Suggested Solution