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| Term |
Description |
| hacker |
Hacker, in general computing terms means to cleverly solve programming problems. It is not necessarily associated with intruders breaking into remote computer systems via communication networks (a.k.a. crackers), even though it is sometimes used in that context by journalists.
Following are definitions of the different contexts/subcultures of the term:
hacker (computer security context) is someone who seeks and exploits weaknesses in a computer system or computer network, debugging, or fixing security problems.
hacker (programmer) is a person who enjoys the intellectual challenge of creatively overcoming and circumventing limitations of programming systems, trying to extend their capabilities.
hacker (hobbyist) is a person who enjoys exploring the limits of what is possible, building, rebuilding, and modifying to make software/hardware better or faster. |
| HDCP |
HDCP (High-bandwidth Digital Content Protection) is a form of Digital Rights Management (DRM) developed by Intel to control digital audio and video content as it travels across DVI or HDMI connections.
The specification is proprietary, and creating an implementation of HDCP requires a license by Digital Content Protection, an Intel subsidiary.
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| HDSL |
HDSL (High-data-rate Digital Subscriber Line, High-speed DSL).
One of the older DSL implementations, providing equal upstream and downstream traffic. HDSL requires minimum two twisted pairs and offers data rates up to 2,048 Kbps. |
| HDTV |
HDTV (High Definition television) is a term describing television with significantly more picture information (resolution) than that provided by a good NTSC or PAL television signal. The specific resolution (or definition) of HDTV can vary according to specifications, however it is typically about twice the resolution of standard signals in both the horizontal and vertical direction. HDTV often has a wider aspect ratio. To transfer the required additional resolution data through the narrow frequency TV channels, frames are digitized and compressed before they are transmitted, and then decompressed when they reach the TV. |
| headend |
headend is a general term that refers to the point at which all cable television programming is collected and formatted for placement on the cable system.
The headend master facility is typically a secure building (or PLC substation) housing several large satellite dishes for reception of cable/satellite TV networks, antennae, and/or fiber optics, as well as electronic equipment used to receive, process and re-transmit video and data over the local cable infrastructure. |
| header |
header refers to the first part of a data cell or packet, containing such information as source and destination addresses, and instructions on how the telecommunications network is to handle the data. The header is part of the overhead in a data transmission protocol.
For typical TCP/IP transmissions (most Internet traffic), the header is usually 40 bytes of each packet (20-byte TCP and 20-byte IP headers). Note TCP and IP headers can be larger than 20 bytes if "options" are enabled. ICMP headers (as in pings) are 28 bytes. UDP headers are 8 bytes. |
| HFC |
HFC (Hybrid Fiber Coax) is a distribution network commonly used for Cable Television. The cable segments closer to the headend are optical fiber, while those closer to the customer are coaxial cable. The transition point from fiber to coax varies, and in many places, fiber is extended further into the network in successive upgrades. The signal is normally modulated onto an RF carrier throughout the system. Thus, HFC networks allow the physical medium to be upgraded without changing the signal format or capabilities. |
| HomePlug |
HomePlug is a set of standards developed by the HomePlug Powerline Alliance trade association for powerline home networking over existing AC home electrical wires.
HomePlug 1.0 - the first HomePlug specification, widh PHY data rate of 14Mbps
HomePlug AV - offers peak data rate of 200 Mbps at the physical layer, and about 80Mbps at the MAC layer. Some proprietary extensions allow for peak PHY-rate of 500 Mbps.
HomePlug AV2 - 20% faster than HomePlug AV 500, often sold as HomePlug 600.
HomePlug Green PHY - uses up to 75% less energy than AV and has peak rates of 10 Mbps. GreenPHY is a subset of HomePlug AV intended for use in the smart grid for smaller appliances, such as smart meters and HVAC thermostats.
HomePlug Access BPL - BPL (Broadband over Power Lines) internet access technology, subsequently merged into the IEEE 1901 standard. |
| HomeRF |
HomeRF is a 1.2Mbps wireless LAN (WLAN) standard, lagging behind 802.11 mainly because of its data rate.
A newer, HomeRF version 2.0 spec with 10Mbps throughput and the ability to support multiple channels of voice communication without interfering with or using data transmission bandwidth is being introduced.
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| hop |
A hop is the trip a data packet takes from one router to another in a packet-switching network. On a routed TCP/IP network, such as the Internet, the hop count is kept in the packet header and used to detect routing loops (packets with excessive hop count are discarded). The hop count is an important metric in finding the shortest path between nodes, and can be more significant than their geographical separation. |
| hotspot |
hotspot - an area covered by an access point providing a wireless internet connection. |
| HPNA |
Home Phone Networking Alliance |
| HSDPA |
HSDPA (High-Speed Downlink Packet Access) is a 3G mobile telephony communication protocol in the HSPA family, which allows higher data transfer speeds and capacity.
Current HSDPA deployments support down-link speeds of 1.8, 3.6, 7.2 and 14.4 Mbit/s. Further speed increases are available with HSPA+, which provides speeds of up to 42 Mbit/s downlink. |
| HSPA |
HSPA (High Speed Packet Access) is a collection of high-speed 3G digital data services provided by cellular carriers worldwide that use the GSM technology. HSPA protocols extend and improve the performance of existing UMTS (Universal Mobile Telecommunications System) protocols.
HSPA service works with HSPA cellphones as well as laptops and portable devices with HSPA modems. The two established standards of HSPA are HSDPA and HSUPA |
| HTPC |
HTPC ia an acronym for: Home Theater Personal Computer |
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