Quantum and Evolution Series Installation and Operating Handbook
7-129
Options:
Unbalanced
Balanced
Factory default:
Unbalanced
Description:
Sets the G.703 line format.
Edit-Unit-Interface-Terrestrial-G.703 Line Encoding Screen
Options:
AMI
B3ZS
B6ZS
B8ZS
HDB3
Factory default:
AMI
Description:
Selects the different line coding available for the required data rate. The
objective is to limit the number of contiguous zeros transmitted on the
G.703 line. This is necessary with G.703 as with AMI a `mark` (logic one)
is sent as a pulse on the line, and a `space` (logic zero) is set as the
absence
of a pulse on the line. If there are too many contiguous spaces
the G.703 receiver fails to recover the clock properly (as there are no
incoming pulses for a while) and it causes data errors. HDB3 and B8ZS
for example, are both methods of ensuring that no more than three or
eight zeroes respectively occur on a G.703 line by substituting strings of
more than this number of zeroes with another code, in turn this code is
detected at the end of the G.703 line and replaced with the correct
number of zeroes again.
G.703 line encoding: [AMI]
1:AMI #:B3ZS #:B6ZS
4:B8ZS #:HDB3
