Rayleigh fadingRayleigh fading is a statistical model for the effect of a propagation environment on a radio signal, such as that used by wireless devices. Rayleigh fading models assume that the magnitude of a signal that has passed through such a transmission medium (also called a communication channel) will vary randomly, or fade, according to a Rayleigh distribution — the radial component of the sum of two uncorrelated Gaussian random variables.
Carrier Sense Multiple Access with Collision DetectionCarrier Sense Multiple Access/Collision Detection (CSMA/CD) est un protocole qui gère le partage de l'accès physique. Il est utilisé dans les premières normes du réseau Ethernet (IEEE 802.3). Carrier Sense Multiple Access (CSMA) : Accès multiple avec écoute de la porteuse. Cette méthode permet à une station d'écouter le support physique de liaison (câble ou fibre) pour déterminer si une autre station transmet une trame de données (niveau déterminé de tension électrique ou de lumière).
Radio receiver designRadio receiver design includes the electronic design of different components of a radio receiver which processes the radio frequency signal from an antenna in order to produce usable information such as audio. The complexity of a modern receiver and the possible range of circuitry and methods employed are more generally covered in electronics and communications engineering.
Subnetwork Access ProtocolThe Subnetwork Access Protocol (SNAP) is a mechanism for multiplexing, on networks using IEEE 802.2 LLC, more protocols than can be distinguished by the 8-bit 802.2 Service Access Point (SAP) fields. SNAP supports identifying protocols by EtherType field values; it also supports vendor-private protocol identifier spaces. It is used with IEEE 802.3, IEEE 802.4, IEEE 802.5, IEEE 802.11 and other IEEE 802 physical network layers, as well as with non-IEEE 802 physical network layers such as FDDI that use 802.
Average bitrateIn telecommunications, average bitrate (ABR) refers to the average amount of data transferred per unit of time, usually measured per second, commonly for digital music or video. An MP3 file, for example, that has an average bit rate of 128 kbit/s transfers, on average, 128,000 bits every second. It can have higher bitrate and lower bitrate parts, and the average bitrate for a certain timeframe is obtained by dividing the number of bits used during the timeframe by the number of seconds in the timeframe.
Municipal wireless networkA municipal wireless network is a citywide wireless network. This usually works by providing municipal broadband via Wi-Fi to large parts or all of a municipal area by deploying a wireless mesh network. The typical deployment design uses hundreds of wireless access points deployed outdoors, often on poles. The operator of the network acts as a wireless internet service provider. Municipal wireless networks go far beyond the existing piggybacking opportunities available near public libraries and some coffee shops.
Ghosting (television)In television, a ghost is a replica of the transmitted image, offset in position, that is superimposed on top of the main image. It is often caused when a TV signal travels by two different paths to a receiving antenna, with a slight difference in timing. Common causes of ghosts (in the more specific sense) are: Mismatched impedance along the communication channel, which causes unwanted reflections. The technical term for this phenomenon is ringing.
MAC spoofingMAC spoofing is a technique for changing a factory-assigned Media Access Control (MAC) address of a network interface on a networked device. The MAC address that is hard-coded on a network interface controller (NIC) cannot be changed. However, many drivers allow the MAC address to be changed. Additionally, there are tools which can make an operating system believe that the NIC has the MAC address of a user's choosing. The process of masking a MAC address is known as MAC spoofing.
Mac ProLe Mac Pro est une station de travail 64 bits d'Apple. Il est présenté pour la première fois lors de la WWDC d’. Il remplace le Power Mac G5 dont il reprend le design, et signe la disparition de la dénomination Power Mac parmi les produits Apple. Le , Apple a mis à jour ses Mac Pro. Ces derniers pouvant accueillir deux processeurs Intel Xeon Nehalem cadencé jusqu'à . Le , Apple renouvelle sa gamme en intégrant de nouveaux processeurs Intel Xeon Westmere et la possibilité d'avoir jusqu'à douze cœurs à disposition.
Macintoshvignette|upright=1.2|alt=Un grand ordinateur tout-en-un en aluminium, écran plat large.|Un modèle d'iMac lancé en . Macintosh (, en anglais : ) ou Mac est une série de différentes familles d'ordinateurs personnels conçus, développés et vendus par Apple. Le premier Macintosh est lancé le (il a été renommé Macintosh 128K dès le lancement du Macintosh 512K). Il constitue le premier succès commercial pour un ordinateur utilisant une souris et une interface graphique (au lieu d'une interface en ligne de commande).
