1000BASE-T/100BASE-TX/10BASE-T Physical Layer Compliance Tests Manual
Intel Confidential
127
Troubleshooting Guide
Figure G-2. Effects of low open circuit inductance for 0
≤
t
≤
∞
.
Note:
The long pulse in the graphic above is meant to represent the effect of tens to hundreds of wide
positive pulses in a row.
Magnetics that meet the open circuit inductance specification keep the signal quality from
degrading as quickly. Systems that fail this specification may have poor BER results over long
cables depending on the ability of the receiver to handle these degrading signals. Fortunately, these
types of signals are never as long as shown above, so the problem will not usually be so dramatic
that all of the packets will disappear. Normally, the extra inductance in the magnetics will improve
the signals enough to prevent the majority of the errors.
G.9
Duty Cycle Distortion (ANSI specification 9.1.8)
Different receivers handle signals with duty cycle distortion differently. The general symptom of
this problem will be that the receiver may drop some bits or it may think some bits are present
when they really are not. This problem can be aggravated on a longer cable.
Time
Time
Original Signal
Signal after going through a generic
transformer
Voltage
(V)
Voltage
(V)
Time
Signal Improvement with high open
circuit inductance
Voltage
(V)