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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.

Half-duplex  Transmission
 


Hard-clad Silica Fiber


An optical fiber having a silica core and a hard polymeric plastic cladding intimately bounded to the core.

 


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).

 




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).

Headend
 


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 (Hybrid Fiber Coax)
 


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.

 


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).

 


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.