ADTRAN Express L1.5, Руководство пользователя

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61202192L1-1 Express L768/L1.5 User Manual 3
Chapter 1
Understanding HDSL and
the Express L768/L1.5
HDSL OVERVIEW
High Bit Rate Digital Subscriber Line (HDSL) is rapidly becoming the service
providers’ technology of choice for the deployment of T1 services: according
to recent estimates, over 60% of today’s T1 installations use HDSL technology.
Instead of traditional methods requiring multiple T1 repeaters, HDSL allows
the telephone companies to quickly deploy a T1 circuit over Carrier Serving
Area (CSA) loops (9,000 feet on 26 AWG wire or 12,000 feet on 24 AWG wire)
without the need for loop conditioning or repeater installation. The benefits
HDSL offers over traditional T1 span lines represent large cost savings for the
service provider because
• HDSL circuits can be deployed in days as opposed to weeks
• HDSL circuits can be deployed without the need for
- line repeaters on CSA loops
- binder group separation
- bridge tap removal for bridge taps totaling less than
2,500 feet (no single bridge tap greater than 2,000 feet)
• HDSL circuits virtually eliminate cross talk and loop impairment prob-
lems
• Safer class A3 voltages eliminate need for special training or procedures.
Adtran provides a full line of HDSL products that are the price/performance
leaders in the industry.