Agilent Technologies Agilent 4396B - 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 di erent 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 e ect.
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 speci ed in terms of group
delay or envelope delay . This is especially true of telecommunications
components and systems .
Group delay is the di erence 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