Unit Frekuensi Ambang
Whereas there is no formal specification for "half rack", the term half-rack can have different separate meanings: It can describe equipment that fits in a certain number of rack units, but occupy only half the width of a 19-inch rack (9.5 inches (241.30 mm)). These are commonly used when a piece of equipment does not require full rack width, but may require more than 1U of height.[citation needed] For example, a "4U half-rack" DVCAM deck occupies 4U (7 in) height × 9.5 in width, and in theory, two 4U half-rack decks could be mounted side by side and occupy the 4U space. It can also describe a unit that is 1U high and half the depth of a 4-post rack (such as a network switch, router, KVM switch, or server), such that two units can be mounted in 1U of space (one mounted at the front of the rack and one at the rear). When used to describe the rack enclosure itself, the term "half-rack" typically means a rack enclosure that is half the height (22U tall). There is also a "half rack width" size being used in IT applications where a device conforms to a smaller than 9.5-inch width so that these "half rack width" appliances may be used in a chassis system that fits the traditional 19-inch rack space, but allows for these 8.4-inch-wide "half rack width" appliances to be inserted and removed easily without tools or the need to remove adjacent hardware. This "half rack width" concept is popular in applications where IT equipment is being used by military who are unable to use traditional 1U full-depth IT appliances due to their large size.
