http://pikibook.com/electrical-engineering/telecommunications/essentials/ en-us Mon, 13 Apr 2009 07:15:54 -0500 Mon, 13 Apr 2009 07:15:54 -0500 http://blogs.law.harvard.edu/tech/rss 1440 http://pikibook.com/electrical-engineering/telecommunications/essentials/communications-fundamentals ... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/communications-fundamentals http://pikibook.com/electrical-engineering/telecommunications/essentials/telecommunications-technology-fundamentals Telecommunications Technology Fundamentals This chapter talks about the types of transmission lines and network connections, the electromagnetic spectrum, and what bandwidth is all about in the emerging broadband era. It looks at the differences between analog and digital signals, and it discusses... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/telecommunications-technology-fundamentals http://pikibook.com/electrical-engineering/telecommunications/essentials/transmission-lines Transmission Lines Two prerequisites must be satisfied to have successful communication. The first prerequisite is understandability. The transmitter and receiver must speak the same language. It doesnt matter how big or how clean the pipe between the two endpoints. If theyre not speaking the same... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/transmission-lines http://pikibook.com/electrical-engineering/telecommunications/essentials/types-of-network-connections Types of Network Connections Three major types of networks connections can be made: Switched network connections A switched connection is referred to as a dialup connection. This implies that it uses a series of network switches to establish the connection between the parties.Leased-line network connections... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/types-of-network-connections http://pikibook.com/electrical-engineering/telecommunications/essentials/the-electromagnetic-spectrum-and-bandwidth The Electromagnetic Spectrum and Bandwidth The following sections talk about bandwidth and about where the various transmission media lie within the electromagnetic spectrum. The Electromagnetic Spectrum When electrons move, they create electromagnetic waves that can propagate through free space. James... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/the-electromagnetic-spectrum-and-bandwidth http://pikibook.com/electrical-engineering/telecommunications/essentials/analog-and-digital-transmission Analog and Digital Transmission There are a number of differences between analog and digital transmission, and it is important to understand how conversions between analog and digital occur. Lets look first at the older form of transmission, analog. Analog Transmission An analog waveform (or signal)... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/analog-and-digital-transmission http://pikibook.com/electrical-engineering/telecommunications/essentials/multiplexing Multiplexing Multiplexers, often called muxes, are extremely important to telecommunications. Their main reason for being is to reduce network costs by minimizing the number of communications links needed between two points. Like all other computing systems, multiplexers have evolved. Each new generation... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/multiplexing http://pikibook.com/electrical-engineering/telecommunications/essentials/political-and-regulatory-forces-in-telecommunications Political and Regulatory Forces in Telecommunications New developments always bring politics with them. Different groups vie for money, power, the ability to bring new products to market first and alone, and the right to squash others new ideas. A prominent characteristic of the telecommunications... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/political-and-regulatory-forces-in-telecommunications http://pikibook.com/electrical-engineering/telecommunications/essentials/traditional-transmission-media Traditional Transmission Media Transmission media are the physical pathways that connect computers, other devices, and people on a networkthe highways and byways that comprise the information superhighway. Each transmission medium requires specialized network hardware that has to be compatible with... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/traditional-transmission-media http://pikibook.com/electrical-engineering/telecommunications/essentials/twisted+pair Twisted-Pair The historical foundation of the public switched telephone network (PSTN) lies in twisted-pair, and even today, most people who have access to networks access them through a local loop built on twisted-pair. Although twisted-pair has contributed a great deal to the evolution of communications,... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/twisted+pair http://pikibook.com/electrical-engineering/telecommunications/essentials/coaxial-cable Coaxial Cable The second transmission medium to be introduced was coaxial cable (often called coax), which began being deployed in telephony networks around the mid-1920s. Figure 2.2 shows the components of coax. In the center of a coaxial cable is a copper wire that acts as the conductor, where the... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/coaxial-cable http://pikibook.com/electrical-engineering/telecommunications/essentials/microwave Microwave Microwave was used during World War II in military applications, and when it was successful in that environment, it was introduced into commercial communications. Microwave was deployed in the PSTN as a replacement for coaxial cable in the late 1940s. As mentioned earlier, twisted-pair and... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/microwave http://pikibook.com/electrical-engineering/telecommunications/essentials/satellite Satellite In May 1946, Project RAND released Preliminary Design of an Experimental World-Circling Spaceship, which stated, "A satellite vehicle with appropriate instrumentation can be expected to be one of the most potent scientific tools of the Twentieth Century. The achievement of a satellite... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/satellite http://pikibook.com/electrical-engineering/telecommunications/essentials/fiber-optics Fiber Optics In the late 1950s and early 1960s, a number of people were working in the realm of fiber optics simultaneously. Charles Kao, who was a scientist with ITT, is often acknowledged as being one of the fathers of fiber optics. Kao theorized that if we could develop a procedure for manufacturing... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/fiber-optics http://pikibook.com/electrical-engineering/telecommunications/essentials/establishing-communications-channels Establishing Communications Channels This chapter discusses the key definitions and characteristics associated with establishing communications channels. It covers networking modes and switching modes, including the differences between routing and switching. It also covers the details of circuit switching... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/establishing-communications-channels http://pikibook.com/electrical-engineering/telecommunications/essentials/establishing-connections-networking-modes-and-switching-modes Establishing Connections: Networking Modes and Switching Modes For messages to travel across a network, a transmission path must be established to either switch or route the messages to their final destinations. Therefore, network providers need a mechanism that allows them to deliver the proper connections... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/establishing-connections-networking-modes-and-switching-modes http://pikibook.com/electrical-engineering/telecommunications/essentials/the-pstn-versus-the-internet The PSTN Versus the Internet In one very important fashion, the PSTN and the public Internet are one and the same thing: They both exist on the same physical infrastructure. There would be no Internet without the PSTN. The communications links, or backbones, that ISPs run on are delivered over the PSTN,... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/the-pstn-versus-the-internet http://pikibook.com/electrical-engineering/telecommunications/essentials/the-pstn The PSTN This chapter talks about the public switched telephone network (PSTN). It discusses what comprises the PSTN, what sorts of technologies have been used to complete the connections, how the signaling systems operate, and the typical components and transmission capacities of the basic backbone... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/the-pstn http://pikibook.com/electrical-engineering/telecommunications/essentials/the-pstn-infrastructure The PSTN Infrastructure Views about what a network should be designed to support and what the infrastructure should be composed of have changed quite a bit over the years, as applications and technology have changed. Before discussing what is needed in a network today, this chapter takes a look at how... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/the-pstn-infrastructure http://pikibook.com/electrical-engineering/telecommunications/essentials/the-transport-network-infrastructure The Transport Network Infrastructure The transport network includes two main infrastructures. The first is the PDH, also known as T-carrier, E-carrier, and J-carrier wideband transmission standards. This infrastructure was first introduced in the early 1960s. The second infrastructure of the transport... Mon, 13 Apr 2009 07:15:54 -0500 http://pikibook.com/electrical-engineering/telecommunications/essentials/the-transport-network-infrastructure