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Computer Engineering Articles
Page 27 of 35
What is 100Base-TX?
100BASE-TX is the technical name of Fast Ethernet over twisted pair cables. It is a predominant form of Fast Ethernet carrying data traffic at 100 Mbps (Mega bits per second) in local area networks (LAN). It was launched as the IEEE 802.3u standard in 1995. Here, 100 is the maximum throughput, i.e. 100 Mbps, BASE denoted use of baseband transmission, and TX denotes use of twisted pair cables in Fast Ethernet.PropertiesThis has either two pairs of unshielded twisted pairs (UTP) category 5 wires or two shielded twisted pairs (STP) type 1 wires.One of these pairs transmits frames from hub to ...
Read MorePower line communications (PLC)
Power line communications (PLC) allows data communications over conductors that are simultaneously used for transmission of electrical power.PLCs work by adding a modulated carrier signal, formed by superimposing data signal over low frequency power signal. Electrical signals transmit at 50 – 60 Hz, while the data signals transmit in the order of MHz.PLCs are also known as power line carrier, power line digital subscriber line (PDSL), or power line networking (PLN).Types of PLC:Narrowband PLC: They work at lower frequencies of 3-500KHz. Their data rates are low but have high range of several kilometres. They are used in the Smart Grid.Broadband ...
Read MoreThe Maximum Data Rate of a Channel
Data rate refers to the speed of data transfer through a channel. It is generally computed in bits per second (bps). Higher data rates are expressed as Kbps ("Kilo" bits per second, i.e.1000 bps), Mbps ("Mega" bits per second, i.e.1000 Kbps), Gbps ("Giga" bits per second, i.e. 1000 Mbps) and Tbps ("Tera" bits per second, i.e. 1000 Gbps).One of the main objectives of data communications is to increase the data rate. There are three factors that determine the data rate of a channel:Bandwidth of the channelNumber of levels of signals that are usedNoise present in the channelData rate can be ...
Read MoreWhat is a Fourier Analysis?
Fourier analysis is a method of representing general functions by approximate sum of simple trigonometric functions. The method is named after mathematician Jean Baptiste Joseph Fourier who formulated and proved the Fourier series. Fourier analysis is used in electronics, communications and acoustics.The Fourier series decomposes a periodic function as a sum of sine and cosine components as expressed below:where, g(t) is the periodic functionT is the time periodf is the fundamental frequency expressed as 1/Tan is the sine amplitude of the nth harmonicbn is the cosine amplitude of the nth harmonicc is a constantThe values of an, bn and c ...
Read MoreAdvanced Mobile Phone System
Advanced mobile phone system (AMPS) was a standard for analog cellular phone system developed by Bell Labs and officially introduced by AT&T in 1983.FeaturesIt is an analog system based on the initial electromagnetic spectrum allocation for cellular service by the Federal Communications Commission.It uses frequency division multiple access (FDMA) for multiple simultaneous conversations.Frequency ranges within the 800 and 900 MHz are allocated for cellular telephones in AMPS. Half of the signal is used for sending signals and half is used for receiving signals.It has a high bandwidth requirement particularly when the number of conversations is very high.It was the first ...
Read MoreCellular Architecture
Cellular architecture is constituted of the following −A network of cells each with a base station.A packet switched network for communication between the base stations and mobile switching centers.The public switched telephone network to connect subscribers to the wider telephony networkCellular ConfigurationIn all cellular systems, land area is divided into a number of cells each with its radio service. In AMPS the area is large which in digital services, the area is much smaller.Conventionally cells are hexagonal in shape.Each cell uses a frequency range that is not used by its adjacent cells. However frequencies may be reused in non-adjacent cells.At ...
Read MoreThe Mobile Telephone System
Mobile telephone service (MTS) connects mobile radio telephones with other networks like public switched telephone networks (PSTN), other mobile telephones and communication systems like Internet.Basic Mobile Communications SystemMobile phones and other mobile devices, called mobile stations are connected to base stations. Communication between the mobile stations and the base stations are done by wireless radio signals, which may be both data signals and voice signals. Each base station has a coverage area around it, such that mobile stations within this area can connect provided they have access permissions. Base stations contain transmitters and receivers to convert radio signals to electrical ...
Read MoreThe Local Loop
In a telephone system, the local loop is a two-wire connection between the subscriber’s house and the end office of the telephone company. It is commonly referred to as the “last mile” of the telephone network. The loop may run from 1km to as far as 10 km.CompositionTraditionally, local loops are composed of twisted pair copper cables. The old local loops have several limitations − narrow bandwidth, high attenuation, distortion of symbols, crosstalk's etc.In recent times, copper wires are being replaced by fiber optic cables for faster and more accurate performance. Installation of fiber cables is popularly known as FttH ...
Read MoreStructure of the Telephone System
The telephone system model is organized as a highly redundant, multilevel hierarchy. It comprises of the following components −Telephone of the subscriber or end userEnd office − Local central office directly connected to end user at a distance of 1 – 10km.Local loop − A two-way connection between the telephone and the end office.Toll office − switching centres which are called tandem offices when located within the same local area.Toll connecting trunk − Lines that connect end offices with toll offices.Intermediate switching offices − Interconnected non-hierarchical switching offices for connecting toll offices.Inter toll trunk − Very high bandwidth channels that ...
Read MoreFiber Optics vs Satellites
Fiber optic communications and satellite communications are complementary to each other. Their properties are very different from one another and consequently their usage varies.Comparison between satellite communication and optical fiber communication can be done based upon the following areas −TerrainSatellite communication is best suited for rough terrains, poorly connected areas and places where it is difficult to lay wires.On the other hand, fibers are suited for urban areas with good infrastructures, where it is convenient to lay communication lines.BandwidthFiber optic promises extremely higher bandwidth with negligible electromagnetic interference. Satellites have lesser bandwidth and are prone to interferences.Data Rate and DelayThe ...
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