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PVA-3000 Reference Manual
December 2, 2019 Sifos Technologies Page
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Impairment Description Asymmetric Features Impair Ext.
Analyzer ?
Line Loss
Model IEEE 802.3 worst case cabling system
Insertion Loss (-24 dB @ 100MHz). See
Figure 2.4 .
Uses Line Impair switches in Figure 2.1 .
Apply asymmetrically to Pair 1+2,
Pair 3+4, or symmetrically to
Pairs 1-4 YES
Mismatch
Create fixed 12dB (return loss) mismatch load
at test port interface. Apply asymmetrically to Pair 1+2,
Pair 3+4, or symmetrically to
Pairs 1-4 YES
Alien
Crosstalk
(Noise)
Insert random noise spectrally shaped to
~100BaseTx (
see Figure 2.5 )
Noise level is Programmable from
–6dB to
+21.5dB where 0 dB= 40mVpp noise and
–4
dB = 25mVpp.
Port-under-test experiences
2.7dB higher noise than TEST
PHY on all pairs. Mismatch
impairment may be used to fully
remove noise from Pairs 1+2 or
Pair 3+4. YES
Tx Clock
Offset
Adjust absolute transmit timing up or down
from 125Msymbol / second Uniformly applied to test port and
port-under-test NO
Tx Clock
Jitter
Add contoured jitter with 5KHz roll-off
programmable from
–6 dB to +24 dB where 0
dB is 1.4nsec pk-pk jitter
Uniformly applied to test port and
port-under-test NO
Tx Level
Adjust output level up or down by +1 dB
where center level is
–2.6 dB below nominal
output levels
Only affects transmitted signals NO, inline path
adds
–2.6dB fixed
loss
Tx Slew
Adjust transmitted signal rise time from below
3 nsec to above 4.8 nsec. Only affects transmitted signals NO
2.2.8. PVA Line Loss and
Mismatch Impairments
Figure 2.5 shows actual insertion
loss performance for each of 4 pairs
with the
Line Loss impairment
invoked. Also shown is the IEEE
802.3 worst case cabling system
insertion loss. The Line Loss
impairment is also designed to
maintain 100

match +6

up to
100MHz with worst case return loss
< -14 dB. The impairment is also
designed to approximate the linear
phase vs frequency response of a
cable straight-line response up to
100MHz.
The
Line Loss impairment may be
applied uniformly to pairs 1-4, or
may be applied selectively to pairs 1+2 or pairs 3+4. This allows an outgoing 10/100BaseT signal to experience the
impairment without a commensurate impairment applied to the incoming signal.
Each test port also provides a fixed, wideband –12dB (return loss)
Mismatch that can be connected. This is included
primarily to support calibrations, but may also be utilized as a form of impairment. Just like the Line Loss impairment,
the mismatch may be applied asymmetrically to pairs 1+2 or pairs 3+4, or uniformly to all four pairs. When the
mismatch is connected to any given pair, the Alien Crosstalk (noise source) is electrically isolated from that pair
meaning that the mismatch impairment is also utilized to apply Alien Crosstalk asymmetrically.
Both the
Line Loss and Mismatch impairments are available to any devices connected to the THRU interface. Hence
one or both impairment types may be applied in line with external packet analyzers.
2.2.9. PVA Alien Crosstalk Impairment
The Alien Crosstalk impairment models a random noise component that may be selectively added to all four pairs.
The noise source is designed to approximately model the 100BaseTx power spectrum so that upper frequencies are not
disproportionately impaired, thus implementing the recommendation of IEEE 802.3 clause 40.6.1.3.4. Figure 2.6
depicts the spectral shaping of the Alien Crosstalk impairment.
Insertion Loss - PVA Line Loss
(50KHz to 100MHz)
-30.0
-27.5
-25.0
-22.5
-20.0
-17.5
-15.0
-12.5
-10.0
-7.5
-5.0
-2.5
0.0
0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00
Frequency (MHz)
A
tte
n
u
a
ti
o
n
(d
B
)
Pair 2
Pair 3
Pair 1
Pair 4
IEEE 802.3 Cabling Sys.
Figure 2.5 Line Loss Impairment Actual Insertion Loss vs IEEE 802.3