| Hall effect |
A type of door monitoring built into magnetic locks. |
| Hard Disk |
Non volatile digital data storage device used in PCs. Come in various storage sizes, normally measured in giga-bytes. See Hard Disk Recorder. |
Hard Disk Recorder -
HDR (Digital Video
Recorder - DVR) |
Device that uses digital techniques to record CCTV pictures to a hard disk. The results can be of higher quality than VHS or SVHS, events can be found faster and there is no loss of quality when copies are made. |
| Hardwired |
Method of controlling camera points using multicore cable. |
| Holiday Code |
A VCR timer feature that allows you to assign the Sunday timer settings to up to 20 weekdays per year. Normally used for Bank holidays. |
| Hot Swapping |
Removing and replacing a component of a larger system while the system is receiving power and operating. |
HTML (Hypertext
Mark-up Language) |
A standard for defining documents with hypertext links. HTML is a subset of SGML (Standard Generalised Mark-up Language) and is used to establish links between documents on the World Wide Web. |
HTTP (Hypertext
Transfer Protocol) |
The clients/server protocol used for connections to servers on the World Wide Web. Addresses of Web sites begin with an http://prefix. |
| Hub |
A central connecting device in a network that joins communications lines together in a star configuration. |
| Hz (Hertz) |
Cycles per second. |
