User guide

August 2001 39
Understanding T1 Trunks
The Bipolar signal, also called Alternate Mark Inversion
(AMI), uses 0V to represent zero and alternating positive
and negative pulses to represent ones. AMI is the default
line coding method for T1 boards.
Figure 6 shows the three line coding methods.
Figure 6. T1 Line Coding Methods
10101 11
1
11 100 00
0
00
Bit Stream Code
Binary Signal (Unipolar)
Bipolar (AMI - Alternate Mark Inversion)
Polar Signal
0V
+3V
0V
+1.5V
-1.5V
0V
+3V
-3V