Trochu teorie

PoE (Power over Ethernet) je název řady metod, které umožňují napájet síťová zařízení prostřednictvím krouceného páru a zároveň přenášet data. Je možné napájet zařízení, jako jsou kamery, telefony, přepínače, přístupové body atd.

Exchanging data between at least two computers requires a dedicated computer network has to be created. In such a network, the devices communicate using transmission media via appropriate communication protocols. Not only computers and servers can be connected to a computer network these days, but also CCTV equipment, alarms, smart home components or household appliances.

Twisted-pair cables are used to transmit signals in telecommunication systems and computer networks. The most popular twisted-pair cables are composed of four pairs of twisted insulated copper wires. The twisting strongly reduces the influence of external electromagnetic interference and mutual interference between the pairs, called crosstalk. Currently, the cables are mainly used in telephony and Ethernet networks.

The Yagi-Uda or Yagi antenna is one of the most popular antenna designs. Despite a comparatively simple construction, it has a high gain, typically greater than 10 dBi. Yagi-Uda antennas can operate in the HF to UHF bands (3 MHz to 3 GHz), but often within a limited bandwidth around the center frequency.

ULTIPOWER Ethernet industrial switches enable data transmission at rates of 10/100 Mbps or 1000 Mbps. Their RJ45 ports support auto-negotiation and Power over Ethernet (PoE) functions. The devices automatically discover PD devices (///Power Device///) compliant with IEEE 802.3af standard and supply power to them. This way, it is easy to power network devices located in places without access to AC lines, such as access points, IP cameras, IP phones etc. The switches have been equipped with optical converters or SFP slots for installing modules changing the transmission medium to fiber.

Twisted-pair cables are used to transmit signals in telecommunication systems and computer networks. Currently they are mainly used in analog telephony and Ethernet networks. Twisted-pair cables may consist of one or more pairs. The twisting strongly reduces the influence of external electromagnetic interference and mutual interference between the pairs, called crosstalk.

Translation of the domain name into the set of numbers is performed by the appropriate DNS server, to which the computer sends a query asking for the translation of the address. After receiving the response with the numeric address, the computer connects to the appropriate computer/server.

WLAN (Wireless Local Area Network) představuje technologii, která umožňuje výstavbu bezdrátových datových sítí s vyhovujícími parametry a poměrně velkým rozsahem aplikací při relativně nízkých nákladech. Další výhodou této technologie je krátká doba potřebná pro její implementaci.