Evolution of Communication Systems PDF

Evolution of Communications Systems Course: History of Engineering Sciences Lecturer: Dr. Mohamed A. El-Shimy Department: Electrical Engineering Department, Affiliation: Alexandria University, Egypt. 0. Introduction  Communication is the process of exchanging words and signs with others that...

Evolution of Communications Systems Course: History of Engineering Sciences Lecturer: Dr. Mohamed A. El-Shimy Department: Electrical Engineering Department, Affiliation: Alexandria University, Egypt. 0. Introduction  Communication is the process of exchanging words and signs with others that enables us to pass information.  The evolution of communication is an ongoing process. Beginning from prehistoric era and with the advancements of technology, humans have developed different methods to communicate.  Examples of communication systems are: o Telegraph and Telephone Systems o Radio and Television Broadcasting o Cellular Mobile Network o Wireless Networks o Satellite Communications Systems o …. Etc. 1. Ancient Systems 1.1. Cave Paintings  The oldest methods of communicating where signs and symbols were used to record events and stories information on the walls and ceiling of caves.  One of the most significant cave paintings is Chauvet Cave in France which was made around 30,000 B.C. 1.2. Smoke and Drum Signals  Prehistoric man relied on fire, smoke, and drum signals to encode information over a limited geographic area.  These signals have very simple meanings like "safe" or "danger" or could be used as a form of alarm system. 1.3. Postal System  In the 6th century BCE, a Persian emperor named Cyrus the Great established the first postal system in the history to communicate from one end of his vast empire to the other.  Later on, other ancient like Egypt, Rome, and China built their own postal systems. 1.4.Pigeon Post  It has been discovered that the pigeons have the ability to find their way back to their nests regardless of the distance.  Travelers brought pigeons along with them, attach messages to them and release them to fly back home.  The first pigeon messaging system was established by Persia and Syria around the 5th century BCE. 1.5. Flag Semaphore  A special code involving the positions of two hand-held flags. Each position and motion represented a letter or number.  It was introduced in the 15th century and used to communicate between ships. 2. Telegraph Systems 2.1. Optical Telegraph  It is a system of pendulums that set up somewhere high like on a tower or the top of a town clock. One of its names is the semaphore visual telegraph.  It is considered as the first telecommunications system in Europe where it was created by two French inventors (the Chappe brothers) in 1790.  The system was then implemented all throughout France and it was widely used in military at the time of French revolution and Napolean period.  The optical telegraph system had been in use for about 60 years till the invention of the electrical telegraph. Operation  The optical telegraph stations are equipped with mechanical rotating arms.  The telegraph would swing its arms around to encode messages into symbols.  Stations were built 10 to 15 km apart which relaying the symbols from one tower to another till it reaches the receiving station.  Messages are received by human eyes, aided by telescope, and the symbols are then decoded by a code book to extract the sending message. 2.2. Electrical Telegraph  In 1838, Samuel Morse and his friends Alfred Vail and Leonard Gale connecting two model telegraphs together with an electric wire.  They discovered that messages can be sent by holding or releasing the buttons in a series of intervals. The letters are represented by combinations of long and short pulse known as Morse code.  Morse was not the first one to think of the idea of sending electric signals across wires, but he was the first to get political support for making it work.  After that, Britain and United States had established telegraph stations within their own countries.  In 1858, the first transatlantic cable was installed to connect England and the United States by telegraph.  In the late 19th century, electric telegraphy signals using Morse code could be successfully transmitted wirelessly by radio waves knowing as radio telegraphy systems.  At the turn of the 2oth century, all long-distance communications depended heavily on the telegraph. By the time, radio and telephone had diminished the impact of the telegraph. 3. Landline Telephone Systems 3.1. Basic Principles  The telephone is a personal type of communication that offers a transmission of sound, typically human voices, over a distance by converting acoustic vibrations to electrical signals.  The word telephone, from the Greek roots, is composed of ‘tele’ means ‘far’ and ‘phone’ means ‘sound’. 3.2. Telephone Device  The main functional components of the telephone instrument are the power source, the switch hook, the dialer, the ringer, the transmitter, the receiver, … etc... Acoustic Telephone  Early history of telephone started when Robert Hooke created an acoustic telephone in 1672 where he discovered that sound could be sent over wire into an attached earpiece or mouthpiece. Electric Telephone  Beginning in the early 19th century, several inventors made several attempts to transmit sound by electric means. The first inventor suggested that was a Frenchman, Charles Bourseul.  In 1849, an Italian innovator Antonio Meucci began developing the design of a talking telegraph or telephone. He had electrical devices in his home to communicate between rooms.  By 1861, Johann Philipp Reis of Germany had designed several instruments for the transmission of sound.  Later in 1870s, two American inventors, Elisha Gray and Alexander Graham Bell, each independently, designed devices that could transmit speech electrically.  In 1876, Bell won the first U.S patent for his design of the electric telephone device that can transmit speech electronically.  At first, Bell telephone was operated by batteries located inside the telephone device. Then, since the 1890s, the telephone supplied current has been generated at the local switching office with standard 48 volts. Photophone  In 1880, Alexander Graham Bell made a photophone device which was capable of transmitting sound in a beam of light. This can be considered as the first wireless communication device in history preceding the radio invention by nearly 20 years.  The photophone functioned similarly to the telephone, except the photophone used light as a means of projecting the information, while the telephone relied on electricity.  Due to practical limitations in technology, the photophone was not recognized in its time till the invention of fiber optics in 1970s. 3.3. Telephone Network System  Telephones are directly wired to a local exchange (central switching office).  In 1882, Bell and others established the Bell Telephone company which is named later AT&T.  The central offices were arranged into network hierarchies for telephone calls between subscribers where it span cities, countries, and all the world.  Bell Telephone Company was the first company to provide network hierarchy was in the United States.  In 1915, Bell made the coast-to-coast call from a land-line phone and it is the first long-distance call made in history.  The first radio-telephone service was established from U.K. to U.S. across the Atlantic Ocean in 1927 and from U.S to Japan across the Pacific Ocean in 1934.  In 1956, the first transatlantic telephone cable was installed from Newfoundland to Scotland.  In the early 1960s, the Bell System installed the first communication link for digital voice transmission where the speech message was digitized into a stream of 1s and 0s. 3.4. Call Number Dialing Manual Operator  In the late of 1800s, the caller and the called phones are connected manually by an operator at the central office to set the call. Pulse Dialing  A traditional rotary dialer was invented in 1890s where it is rotated against the tension of a spring and then released to return to its position. This causes a switch to open and close producing dial pulses.  It was designed for operation an electromechanically switching system.  In 1892, Almon B. Strowger combines the new rotary-dialed telephone with an automated telephone switch.  Each telephone was assigned a unique number where a series of pulses sent to the CO switch corresponding to each digit in the telephone number such that two pulses correspond to the digit 2 and so on. Tone Dialing  Later in the 1960s, an electronic push-button dialing system was introduced by AT&T company which generates a “dual-tone” signal that replaced the “dial pulse” signaling.  The system is based on the concept of dual-tone multifrequency (DTMF), where the dialing digits are assigned to specific push buttons which are arranged in rows and columns that are assigned a tone of frequency.  By pushing a button, a dual-tone is generated that corresponds to the intersection of the column and row at that button.  Each dual tone is composed of a low frequency (697, 770, 852, or 941 Hz) corresponds to rows and a high frequency (1209, 1336, 1477 Hz) corresponds to columns that are sensed and decoded at the switching office.  Notice that Modern push-button telephones can even be able to generate pulse signals. 4. Cellular/Mobile Communication Networks 4.1.Network Principles  A cell phone or mobile phone is a portable telephone that communicates wirelessly to a cellular/mobile network.  The network is distributed over land areas called "cells", each served by at least one fixed-location transceiver which can be used for transmission of voice, data, and other types of content.  In the conventional fixed telephone network, each subscriber is identified by the number of a certain subscriber loop that is connected to a certain fixed telephone socket. In contrast, in a cellular network, the identification is in the telephone set itself where it is located in one cell at a time.  When the cells are joined together, they provide radio coverage over a wide geographic area. This allows mobile phones to communicate with each other and to be connected to the public switched telephone network (PSTN).  The mobile switching center (MSC) acts as a local exchange that provides switching and control functions, and it also keeps track of the subscribers’ locations in order to be able to route a call to the destination.  The BSs are connected to the MSC by a microwave link or by a cable line (optical or copper cable) and the MSC is connected to the PSTN. 4.2. History of Mobile Communications 1940s The first system offering mobile telephone service (car phone) in the US. 1964 Bell Laboratories improved the mobile service by adding full-duplex features. 1968 The Federal Communication Commission (FCC) reallocated the frequency spectrum (800 to 900 MHz) to the user. 1973 The first cellular mobile call was made by Martin Cooper. The used phone was a prototype for Motorola’s first mobile phones. 1981 Japan launched the first commercially automated cellular network. 4.3. Mobile Generations  The mobile communication systems have been evolved from the first generation (1G) to currently the fifth generation (5G). 5. Radio Broadcasting 5.1. Basic Principles  It is a unidirectional wireless transmission of an audio signal over radio waves to reach a wide audience.  The radio industry is one of the oldest industries in electrical communications. It offers distinct products in the form of entertainment and information, and access to audiences for radio advertising. 5.2. History of Radio Broadcasting  By the end of the nineteenth century, innovators were working in transmitting Morse code via the wireless radio technology. Over time, the transmission of dots and dashes gave them a way to broadcast voice and music signals.  In 1896, an Italian inventor, Marconi, sent his first long-distance wireless transmission of sound signal over a distance of 2 kilometers.  In 1900, the Canadian Reginald Fessenden was able to wirelessly transmit a human voice.  In 1901, Marconi established the first wireless communication across the Atlanic Ocean between Britain and Newfoundland, earning him the Nobel Prize in physics.  In 1920, KDKA broadcasts the first regular licensed radio broadcast out of Pittsburgh.  Britain was the first European country to establish a radio station where it set up the British Broadcasting Corporation (BBC) in 1924 to broadcast from London.   Starting from 1930s, the radio broadcasting has been used on a large scale such as by the pilots, police forces and so on.  The period of 1930s and 1940s, before the television world, was referred as the golden age of the radio broadcasting 5.3. AM and FM Radio Stations  The radio stations broadcast with different types of analog modulations:  In AM stations, the information is carried by amplitude modulation.  In FM stations, the Information is carried by frequency modulation.  The FM broadcasting began to emerge as an alternative to the standard AM.  Programming is dominated by music on the FM band and by talk and information on the AM band. 6. Television Broadcasting 6.1.Basic Principles  It is a system of broadcasting moving images and sound to a wide audience. It's considered a powerful tool for information, entertainment, and education.  Audio and video contents are created, via microphone and camera respectively, and converted into electronic signals suitable for transmission.  The signals are sent via (1) radio waves, through terrestrial broadcasting, satellite broadcasting, and cable television, or (2) internet protocol television (IPTV), through a high-speed internet connection.  Viewers use antennas for terrestrial TV, dishes for satellite TV, or cable boxes for cable TV to receive and decode the signal back into audio and video for viewing on their televisions.  Broadcasting comes in free (over-the-air) or pay-TV that requires channels subscription. 6.2. Evolution of Television  The beginnings of TV were shown in 1920s by inventors Phillip T. Farnsworth and John Logie Barid.  The first public television broadcast was transmitted in England by John Logie Barid using a mechanical scanning disc.  The first working electronic television prototype is made by Phillip T. Farnsworth. He discovered a method to encode radio waves with an image and then project them back onto the screen.  Color television technology is demonstrated as early as the 1920s with technical challenges and it becomes standardized by the 1950s.  The invention of the video cassette recorders (VCRs) in the 1970s allows viewers to record and watch programs at their convenience.  Stereo sound is introduced in the 1980s, followed by surround sound, further enhancing the audio experience.  Cable and satellite television emerged in the 1980s, offering a wider range of channels and programs, challenging the dominance of traditional networks.  The 2000s brought the digital television (DTV) which is the transition from analog to digital broadcasting in favor of digital signals for improved picture and sound.  The introduction of High-Definition Television (HDTV) was seen in the 1990s and becoming the new TV standard in 2000s.  Television broadcasting continues to evolve, where smart TVs are nowadays equipped with internet connectivity and interactive features. The way to deliver television channels and video content through the internet protocol (IP) is known as IPTV.