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MTT-14B e_Manual D07-00-083P RevA00
Page 82 of 101
4.2 E1 Technology Overview
This section covers the fundamental concepts in 2.048 Mbit/s
technology; sampling a signal, converting this information into a
bitstream, and dividing the bitstream into segments (channels).
This section also touches upon the basics of signalling technolo-
gies like MFR2 and CAS.
4.2.1 Technical Standards
E1 transmission technology is defined by a number of technol-
ogy standards. Such standards allow equipment designers and
service providers to ensure that various pieces of equipment are
compatible and that networks operate in a predictable, reliable
manner. The following standards cover many of the important
aspects of E1 transmission technology:
• ITU G.703: Physical/electrical characteristics of interfaces.
• ITU G.704: Synchronous frame structures.
• ITU G.706: Frame alignment and CRC.
• ITU G.821: Error performance of a international connection.
• ITU G.826: Error performance and transmission quality control.
• ITU M.550/M.2100 Getting an international connection into
service.
• Q.140: Concerns redundant copies from subrate channels.
• Q.400: Concerns CAS (Channel Associated Signaling).
Consult these standards when you need detailed information on
particular aspects of E1 transmission technology.
4.2.2 Basic Definitions
Binary Data: A signal which has been converted into a format
of zeros and ones.
Bit Stream: Binary Data which has been placed in a sequence
at a fixed rate.
Channel: A single portion of the bit stream which is available for
bidirectional communication.
4.2.3 Converting a Voice Signal
To transmit voice over a digital medium, like a 2.048 Mbit/s line.
The analog voice signal must be converted into a binary format.
Then it must be converted to a bit stream suitable for digital
transmission. This conversion can be accomplished through
Pulse Code Modulation as shown in Figure 57.
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