Legacy Technology: All About T1

Legacy Technology: All About T1
This module provides detailed information on the carrier system technology called T1. T1 used to be a principal subject of telecommunications courses, but is now relegated to the back of the book, as T1 is a technology running at 1.5 Mb/s on copper wires, replaced with Gigabit/s Optical Ethernet on fiber.

That said, there are thousands of T1 circuits installed and in use, and some readers of this book have picked it precisely to learn about T1 because they have been tasked with supporting it, or auditing an existing installation.

Power companies, the military and government still have T1s in place, along with T1s at big organizations that are no longer being used, but have been forgotten and are still being paid for each month... a small but appreciated part of any phone company’s revenue.

This chapter on T1 also provides a very detailed explanation of synchronous Time-Division Multiplexing, framing and channels. Since the principles of operation of legacy SONET fiber-optic transmission systems are the same as T1, learning about T1 is also learning about SONET.

Telecom Module 18
Detailed Outline

18 Legacy Technology: All About T1
18.1 T1 History and Applications
18.2 T1 Circuit Components
18.3 Operation
18.4 T1 Framing
..... 18.4.1 Superframe Format
..... 18.4.2 ESF
18.5 Pulses and Line Code: AMI
..... 18.5.1 Repeaters
18.6 Synchronization: Bit-Robbing
18.7 56 kb/s for Data
18.8 B8ZS and 64 kb/s Clear Channels
18.9 How T1 Is Provided
..... 18.9.1 HDSL
18.10 Fractional T1, DACS and Cross-Connects
18.11 Subrate Data Circuits 1.2 kb/s to 56 kb/s
..... 18.11.1 CSUs, DSUs and CSU/DSUs