User guide

August 2001 41

Understanding T1 Trunks

In B8ZS (Binary 8-Zero Substitution), the transmitting end

replaces a series of eight zeros with a ones-rich pattern. B8ZS

coding inserts a bipolar violation as a signal to the receiving end

to reinsert the original zeros. Figure 8 shows the B8ZS

replacement patterns. Notice that the replacement pattern that

is inserted depends on the polarity of the preceding one.

Figure 8. The B8ZS Replacement Pattern

00110011

0000 0000

Original pattern

Replacement pattern

depends on polarity

of the preceding 1.