62
FieldFox User’s Guide
Start, Stop, Center, and Span Gate Times
These settings specify the time in the trace to be gated (in or out). The gate times
can be specified using either Start and Stop or Center and Span.
Press
Gating Start/Stop
A settings table appears that allows you to navigate and select the following
settings. These settings are made exactly like those made on the Transform
Settings table. Learn how on page 56.
Gating Type
This setting defines the type of filtering that will be performed for the gating
function. The gate start and stop flags on the display point toward the part of the
trace you want to keep.
Choose from the following:
o
Bandpass
KEEPS the responses within the Gating Start and Stop times.
o
Notch
REMOVES the responses within the Gating Start and Stop times.
Gating Shape
This setting defines the filter characteristics of the gate function. Choose from
Minimum, Normal, Wide, Maximum.
Time domain Gate Shape setting
Gate Shape
Passband
Ripple
Sidelobe
Levels
Cutoff Time
Minimum Gate
Span
Minimum
0.1 dB
-48 dB
1.4/Freq Span
2.8/Freq Span
Normal
0.1 dB
-68 dB
2.8/Freq Span
5.6/Freq Span
Wide
0.1 dB
-57 dB
4.4/Freq Span
8.8/Freq Span
Maximum
0.01 dB
-70 dB
12.7/Freq Span
25.4/Freq Span
Cutoff time
is the time between the stop time (-6 dB on the filter skirt) and the
peak of the first sidelobe.
T
1
is the gate span, which is equal to the stop time minus the start time.
T
2
is the time between the edge of the passband and the 6 dB point,
representing the cutoff rate of the filter.
T
3
is the time between the 6 dB point and the edge of the gate stopband.