Agilent Technologies Agilent 4396B User Manual
Page 96
Measuring
Phase
Distortion
F
or
many
networks
,
the
amount
of
insertion
phase
is
not
nearly
as
important
as
the
linearity
of
the
phase
shift
over
a
range
of
frequencies
.
The
analyzer
can
measure
this
linearity
and
express
it
in
two
dierent
ways:
Directly
(as
deviation
from
linear
phase).
As
group
delay
(a
derived
value).
Measurement
Setup
This
example
assumes
the
measurement
settings
made
in
\Measuring
Electrical
Length
"
(the
previous
example)
are
still
in
eect.
Deviation
from
Linear
Phase
By
adding
electrical
length
required
to
atten
the
phase
response
,
you
have
already
removed
the
linear
phase
shift
caused
by
the
DUT
.
The
remaining
response
is
the
deviation
from
linear
phase
.
Press
4
Displa
y
5
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
DUAL
CHAN
ON
off
to
NNNNNNNNNNNNNNNNNNNN
on
OFF
.
Figure
5-9.
Deviation
From
Linear
Phase
Press
4
Scale
Ref
5
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
ELEC
DELAY
MENU
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
ELECTRICAL
DELAY
0
4
21
5
when
you
are
nished
with
this
measurement.
Group
Delay
Measurement
The
phase
linearity
of
many
devices
is
specied
in
terms
of
group
delay
or
envelope
delay
.
This
is
especially
true
of
telecommunications
components
and
systems
.
Group
delay
is
the
dierence
in
propagation
time
through
a
device
as
a
function
of
frequency
.
It
is
measured
as
a
ratio
of
phase
change
over
a
sample
delta
frequency
as
follows:
Gr
oup
D el ay
=
0
1
3601F
Where:
1
is
phase
change
[deg]
5-10
Network
Measurement
Examples