CTC Union FMUX-01, User Manual

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Chapter 1. Introduction
1-8
Multiplexer Unit : Apr 2003
1.4 E1 Signal Structure
E1 link line rate
The E1 line operates at a nominal rate of 2.048Mbps.
E1 link line coding
The basic E1 line signal is coded using either the Alternate Mark Inversion (AMI) or
HDB3 rule.
In the AMI format, "ones" are alternately transmitted as positive and negative pulses,
whereas "zeros" are transmitted as a zero voltage level. AMI is not used in most 2.048Mbps
transmissions because synchronization loss occurs during long strings of data zeros.
In the HDB3 format, a string of four consecutive zeros is replaced with a substitute
string of pulses containing an intentional bipolar violation. The HDB3 code substitutions
provide high pulse density so that the receiving equipment is able to maintain
synchronization with the received signal.
The
4-CHANNEL E1 Port Card
supports two E1 line codes:
AMI coding.
HDB3 coding.
The
4-CHANNEL E1 Port Card
supports only transparent unframed format.
1.5 T1(DS1) Signal Structure
T1 link line rate
The T1 line operates at a nominal rate of 1.544Mbps.
T1 link line coding
The basic T1 line signal is coded using either the Alternate Mark Inversion (AMI) or
B8ZS rule.
In the AMI format, "ones" are alternately transmitted as positive and negative pulses,
whereas "zeros" are transmitted as a zero voltage level. AMI is not used in most 1.544Mbps
transmissions because synchronization loss occurs during long strings of data zeros.
In the B8ZS format, a string of eight consecutive zeros is replaced with a substitute
string of pulses containing an intentional bipolar violation. The B8ZS code substitutions
provide high pulse density so that the receiving equipment is able to maintain
synchronization with the received signal.