Agilent Technologies FieldFox N9912A, User Manual

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60 N9912A FieldFox User’s Guide
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.
For all filter shapes T
2
is equal to T
3
, and the filter is the same on both sides of
the center time.
Minimum gate span is twice the cutoff time. Each gate shape has a minimum
recommended gate span for proper operation. This is a consequence of the finite
cutoff rate of the gate. If you specify a gate span that is smaller than the
minimum span, the response will show the following effects:

distorted gate shape that has no passband

distorted shape

incorrect indications of start and stop times

may have increased sidelobe levels.