Introducing AuroraPlus
Issue 5 - 04/01 1-13
µ-Law encoding
This is the type of encoding used in the United States, Japan
and some other regions of Asia. Sampling consists of 8159
levels, divided into 8 segments.
Line Coding Techniques
To overcome the technical difficulties raised by sending
digitised information down a telephone cable originally
designed for 50V pulse dialling and 4kHz speech, line coding
is used. There are a number of different techniques: each one
involves coding digitised speech into different voltages which
can then be transmitted down the telephone lines.
2B1Q line coding
The name 2B1Q comes from the method of coding 2 binary
digits (2B) as one of 4 voltage levels (1Q, where Q stands for
‘quaternary’).
4B3T line coding
The name 4B3T comes from the method of coding 4 binary
digits (4B) as a group of 3 voltage levels (3T, where T stands
for ‘ternary’).
Basic Rate & Primary Rate ISDN
Equipment on an ISDN network may be connected either
through a Basic Rate interface or a Primary Rate interface.
• Basic Rate (BRI) consists of two B channels and one D
channel, known collectively as 2B+D.
• Primary Rate (PRI) consists of 30 B channels and one
D channel (‘30B+D’) in Europe, and 23 B channels and
one D channel (‘23B+D’) in the US.
The B channels contain user data at rates of up to 64Kbps.
The data is switched by the network in order to provide an
end-to-end transmission service.
Chap01.P65 30/04/01, 16:2613
To Next Page
Loading...