Communication engineering principles pdf Continue © 1996-2014, Amazon.com, Inc. or its affiliates 1. DEX2201EX, Engg Communication Principle. Block 1, prepared: Er Lohan Raj NeupaneManmohan Memorial Polytechnic page (en) 1Princips communication engineeringUnit 1 INTRODUCTION1.1 Communication Communication Story - is the process of establishing communication or communication between two points for information exchange. The history of telecommunications - the transmission of signals at a distance for communications purposes - began thousands of years ago with the use of smoke signals and drums in Africa, America and parts of Asia. In the 1790s, Europe had the first fixed semaphore (visual signal transmission system), but it was not until the 1830s that electrical systems began to emerge. Basic Electrical Signals: No 1838: Electric Telegraph 1858: First Transatlantic Telegraph Cable No. 1876: Telephone No. 1880: Telephony via Light Biphonadvanz Electric and Electronic Signals: 1893: Wireless Telegraphy 1896 : Radio 1914: First North American transcontinental telephone call No. 1927: Television No 1927: First commercial radio telephone service, UK-USA 1930: First experimental video phones 1934: First commercial radio service, USA-Japan 1936: World First Public VideoPhone Network 1946 : Limited capacity Mobile telephone service for cars 1956: Transatlantic telephone cable 1962: Commercial communications satellite 1964: Fiber Optical Telecommunications 1965: First North American public video phone network 1969: Computer network 1973: First modern Mobile era (cellular cellular) telephone 1979: INMARSAT ship satellite communication to the shore 1981: First mobile (cellular) telephone network 1982: EMAIL SMTP 1983: Internet 1998: Mobile satellite hand-held telephones 2003 : Skype 2 Internet Telephony. DEX2201EX, Engg Communication Principle. Block 1, prepared: Er Lohan Raj NeupaneManmohan Memorial Polytechnic page (en) 21.2 Modulation, the need for modulation and demonulation in the communication systemModulation is the process of changing one or more properties of the periodic wave shape called carriersignal, with a modulating signal that usually contains information that will be transmitted. In other words, modulation can be defined as the process by which certain characteristics of a signal called a carrier change according to the instant value of another signal called a modulating signal. Characteristics that can be varied amplitudes or frequencies or phases. The information containing the signal is called modulating signals. The signal as a result of processof modulation is called a modulated signal. The need for modulation or the benefits of modulation is needed in the communication system to achieve MultiplexingSimultaneous Transmission Multiple signal on the common channel is possible only during the modulation process.2) The practicality of antennas For effective radiation and signal reception, the antenna must have a length comparable to a quarter of the wavelength of the frequency used. For example, if the 5 kHz signal had to be transmitted without modulation, the length of the antenna would be whiter than th/4 s/4f (3x108)/ (4x5x103) 15 kmEvidly, it would be impossible to build and install such an antenna. However, the length of the antenna can be caused by modulation technology. If the frequency of sound is translated into a radio frequency carrier of frequency5 MHz, the length of the antenna will be whiter than 4 s/4f (3x108)/ (4x5x106) 15 meters The height of the antenna can be achieved practically. 3. DEX2201EX, Engg Communication Principle. Block 1, prepared: Er Lohan Raj NeupaneManmohan Memorial Polytechnic page (en) 33) Remove interference: Because of transmission on the same frequency range, signals interfere with each other. Therefore, in order to keep different signals separate, it is necessary to transfer or transfer them to different port of the electromagnetic spectrum by modulation.4) Noise reduction: noise is the main limitation in communication. Noise can be minimized by several modulation methods. Demodulation is the reverse modulation process that is used to receive the original message signal. Modulation is performed at the end of the transmission, while the demodilation is performed at the receiving end.1.3 Analog Communication System Anolog communication is the type of communication in which the message or information signal for transmission is analog in nature. In analog communication, the analog signal modulates some high media frequency inside the relay to produce a modulated signal. This modulated signal is transmitted via a transmitting antenna to be transmitted through the transmission channel. On the receiver, this modulated signal is removed and processed to restore the original message signal. The image below shows a block diagram of the analog communication system. Currently all AM, FM radio broadcasts and TV.V. Transmissions are examples of analog communication.1.4 The classification of a telecommunications system and their main characteristics of a TELEPHONE: a phone, or a phone, is a telecommunications device that allows two or more users to conduct a conversation when they are not in the same place of each other to be heard directly. The phone converts sound, usually and most effectively to the human voice, into electronic signals suitable for transmission through cables or other means of transmission over long distances, and reproduces such signals in audible form to its user. First patented in 1876 by Alexander Graham Bell and further developed by many others, the phone was the first device in history that allowed people to directly with each other over long distances. Key elements phone microphone (transmitter) to speak in anu earpiece (receiver) that reproduces the voice of a distant person. In addition, most phones contain the caller who produces the sound to announce the incoming phone call, and the dial used to enter the phone number when initiating a call to another phone. Until about the 1970s, most phones used a rotating dial that was out of date with the modern touch-pushing of a button first induced by AST in 1963. The receiver and transmitter are usually built into the phone, which is held up to the ear and mouth during the conversation. The dial can be located either on the phone or on the base unit to which the phone is connected by a wire cord. 4. DEX2201EX, Engg Communication Principle. Block 1, prepared: Er Lohan Raj NeupaneManmohan Memorial Polytechnic page (en) Stationary phone 4A is connected by a pair of wires to the phone network, while the mobile phone, such as a cell phone, is portable and communicates with the telephone network on radio transmissions. The wireless phone has a portable phone that communicates on the radio transmission with the station of the telephone base, which is connected by wire to the phone network. The transmitter converts sound waves into electrical signals that are sent through the telephone network to the receiving phone. The receiving phone converts the signals into the sound in the thereceiver and sometimes the loudspeaker. Phones are a duplex means of communication, which means that they can speak at both ends at the same time. The telephone network, consisting of a worldwide network of telephone lines, fiber optic cables, microwave transmission, cellular networks, communications satellites and underwater telephone cables connected to the commutes, allows any phone in the world to contact anyone else. Each phone line has an identification number called her phone number. To call a phone call, the user enters the number of other phones into the phone's numerical keyboard. Graphic symbols used to refer to a telephone service or phone-related information in print, signage and other media include. Although originally designed for simple voice communication, most modern phones have multi-additive capabilities. They can record conversation messages, send and receive text messages, take pictures and show videos, play music and browse the Internet. The current trend is phones that integrate all mobile communications and computing needs; they're called smartphones. TELEX: The Telex Network is a switched network of teleprinters, similar to the telephone network, to send text messages. This network provided the first common means for international communications recording using standard signaling methods and criteria, as stated in the International Telecommunications (ITU). Telex messages by routing, addressing them to a telex address, such as 14910 ERIC S, where 14910 is a subscriber number, ERIC is an acronym for the name of subscribers and S is the country code. Solutions exist to automatically route messages to various telex terminals within a subscription organization, using various terminal identifiers, such as T148. The main advantage of telex is that receiving a message by the recipient can be confirmed with a high degree of certainty by the response. At the beginning of the message, the sender transmitted the code aWRU (Who aRe yoU), and the WRU code was also sent at the end of the message, so a correct response would confirm that the connection remained continuous during the transmission of the message. This telex is an important advantage over less-verifiable forms of communication, such as telephone and fax. FASCIMILE: A fax machine, sometimes referred to as telecopi or telefax, is a telephone transmission of scanned printed materials (both text and image) to a phone number connected to a printer or other output of the device.