HP 8753D - Page 120

T
able 2-2.
Gate Characteristics
Gate
Shape
P
assband
Ripple
Sidelobe
Levels
Cuto
Time
Minimum
Gate
Span
Gate
Span
Minimum
6
0.1
dB
0
48
dB
1.4/Freq
Span
2.8/Freq
Span
Normal 6
0.1
dB
0
68
dB
2.8/Freq
Span
5.6/Freq
Span
Wide 6
0.1
dB
0
57
dB
4.4/Freq
Span
8.8/Freq
Span
Maximum 6
0.01
dB
0
70
dB
12.7/Freq
Span
25.4/Freq
Span
NOTE:
With
1601
frequency
points
,
gating
is
available
only
in
the
bandpass
mode
.
The passband
ripple and
sidelobe
levels
are
descriptive
of
the
gate
shape
.
The
cuto
time
is
the
time between
the stop
time
(
0
6
dB
on
the
lter
skirt)
and
the
peak
of
the
rst
sidelobe
,
and
is
equal
on
the
left
and
right
side
skirts
of
the
lter
.
Because
the
minimum
gate
span has
no
passband,
it
is
just
twice
the
cuto
time
.
Figure
2-52.
Gate
Shape
13.
T
o
see the
eect of
the gating
in the
frequency
domain,
press:
4
SYSTEM
5
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TRANSFORM
MENU
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TRANSFORM
OFF
4
SCALE
REF
5
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AUTO
SCALE
4
DISPLA
Y
5
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N
DATA
! MEM
N
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N
DISPLAY:
DATA AND
MEMORY
4
SYSTEM
5
N
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TRANSFORM
MENU
N
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NN
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NN
N
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N
SPECIFY
GATE
N
NN
NN
NN
NN
N
N
N
N
N
N
N
N
N
N
N
NN
NN
NN
GATE
OFF
This places the gated response in memory
. Figure
2-53 shows the eect of removing the RF
leakage and the triple travel signal path using gating. By
transforming back to the frequency
domain we see that this design change would yield better out-of-band
rejection.
Making Measurements 2-71