HP 8753D - Page 83

3.
To
activate a
marker to
measure the
group delay
at
a
particular
frequency
,
press:
4
MARKER
5
and turn
the front
panel knob
or
enter
a
value
from
the
front
panel
keypad.
Figure
2-32.
Group
Delay
Example
Measurement
Group
delay
measurements
may
require
a
specic
aperture
(1f)
or
frequency
spacing
between
measurement
points
.
The
phase
shift
between
two
adjacent
frequency
points
must
be less
than
180

,
otherwise
incorrect
group
delay
information
may
result.
4.
T
o
vary
the
eective
group
delay
aperture
from
minimum
aperture
(no
smoothing)
to
approximately
1%
of
the frequency
span,
press:
4
A
V
G
5
N
N
N
N
N
N
N
NN
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
NN
N
N
N
N
SMOOTHING
ON
.
When
you
increase
the
aperture
,
the
analyzer
removes
ne
grain
variations
from
the
response
.
It
is
critical
that
you
specify
the
group
delay
aperture
when
you
compare
group
delay
measurements
.
Figure 2-33. Group Delay Example Measurement with
Smoothing
2-34 Making Measurements