| Half-duplex Transmission: A bidirectional link
that is limited to one-way transfer of data,
i.e., data cannot be sent both ways at the same
time. Also referred to as simplex transmission. |
|
| Hard-clad
Silica Fiber: An optical fiber having
a silica core and a hard polymeric
plastic cladding intimately bounded
to the core. |
| HBT: Abbreviation for heterojunction
bipolar transistors. A very high performance
transistor structure built using more than one
semiconductor material. Used in high performance
wireless telecommunications circuits such as
those used in digital cell phone handsets and
high-bandwidth fiber optic systems. |
|
| HDSL: Abbreviation for high data-rate digital subscriber
line. A DSL operating at a high data
rate compared to the data rates specified for ISDN. |
| HDTV: Abbreviation for high-definition
television. Television that has approximately
twice the horizontal and twice the vertical
emitted resolution specified by the NTSC standard. |
| Headend: 1) A central control device required
within some LAN and MAN systems to provide such
centralized functions as remodulation, retiming,
message accountability, contention control,
diagnostic control, and access to a gateway.
2) A central control device within CATV systems to
provide such centralized functions as remodulation
(illustrated). See also local area network (LAN). |
|
| Hero
Experiments: Experiments performed
in a laboratory environment to test the limits
of a given technology. |
| Hertz (Hz): One cycle per second. |
| HFC
(Hybrid Fiber Coax): A transmission
system or cable construction (illustrated) that
incorporates both fiber optic transmission components
and copper coax transmission components. |
|
| HFC
Network: A telecommunication technology
in which optical fiber and coaxial cable are
used in different sections of the network to
carry broadband content. The network allows
a CATV company to install fiber
from the cable headend to serve nodes located close to business
and homes, and then from these fiber nodes,
use coaxial cable to individual businesses and
homes. |
Click to Enlarge Image |
| HIPPI: Abbreviation for high performance parallel
interface as defined by the ANSI X3T9.3 document,
a standard technology for physically connecting
devices at short distances and high speeds.
Primarily to connect supercomputers and to provide
high-speed backbones for local area networks (LANs). |
| Hot Swap: In an electronic device subassembly or component,
the act or process of removing and replacing
the subassembly or component without first powering
down the device. |
| HP: Abbreviation for homes passed. Homes that could easily and inexpensively be connected to a cable
network because the feeder cable is nearby. |
| Hydrogen
Losses: Increases in fiber connector attenuation that occur
when hydrogen diffuses into the glass matrix
and absorbs some light. |
)
){kind=link}