Verilink AS2000: The Basics (880-502981-001) Product Manual - Manual (Page 144)

Acronyms and Definitions
Glossary-24 Verilink Access System 2000: Basics
H
HDSL High-Density Subscriber Loop is a
four-wire (two-pair) full duplex
service which carries a T1 circuit as
payload over ordinary copper pair
wire.
HDLC A generic link-level protocol in the
OSI model used to manage the
transfer of synchronous, code-
transparent, serial information
between two end points.
high-density bipolar 3 zeros The line code for E1transmission
where four consecutive zero bits
are replaced by an intentional
bipolar violation (BPV) pattern.
The BPV is removed at the far end
and is not counted as an error.
Also see bipolar violation. (HDB3)
HSSI High Speed Serial Interface. A
serial data communication
interface optimized for high
speeds up to 52 Mbit/s. Used to
connect high-bandwidth DTE
applications to a T3 DSU or inverse
multiplexer.
hub office A central location from which an
operator can access a node for
administration and/or testing. The
controller is normally located at
the hub office for dial-up interface
with systems at one or more
distant customer premises.
Hz Hertz: A unit of frequency equal to
one cycle per second.