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**MODULE NO.1: INTRODUCTION TO COMMUNICATION SYSTEMS THEORY** HISTORICAL BACKGROUND *Introduction* - Communication is the process of exchanging information. - Two main barriers of human communications: a. Language b. Distance Breakthrough in communications started in the late 19th centu...

**MODULE NO.1: INTRODUCTION TO COMMUNICATION SYSTEMS THEORY** HISTORICAL BACKGROUND *Introduction* - Communication is the process of exchanging information. - Two main barriers of human communications: a. Language b. Distance Breakthrough in communications started in the late 19th century when electricity and its applications were explored. Electronic communication has increased our ability to share information, such as the telephone, radio, television, and the Internet. ***1800s*** ***Events*** ***Remarks*** ------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------------------------------------------------- 37 Samuel Finley Breeze Morse invented the Telegraph and patented it in 1844. Developed Morse Code (Patterns of dots and dashes) 47 James Clerk Maxwell postulated the Electromagnetic Radiation Theory. 64 James Clerk Maxwell, a Scottish physicist established the Theory of Radio or Electromagnetism which held the rapidly oscillating electromagnetic waves exist and travel at through space with the speed of light. 76 Alexander Graham Bell and Thomas A. Watson invented the Telephone capable of transmitting voice signals (March 10). 82 Nikola Tesla outlined the basic principles of radio transmission and reception. Wireless communication 87 Heinrich Hertz detected electromagnetic waves with an oscillating circuit and establishes the existence of radio waves. Frequency 95 Marchese Guglielmo Marconi discovered ground -- wave radio signals. +-----------------------+-----------------------+-----------------------+ | ***1900s*** | ***Events*** | ***Remarks*** | +=======================+=======================+=======================+ | 01 | Reginald A. Fessenden | | | | transmits the world's | | | | first radio broadcast | | | | using continuous | | | | waves. Marconi | | | | transmits telegraphic | | | | radio messages from | | | | Cornwall, England to | | | | Newfoundland, first | | | | successful | | | | transatlantic | | | | transmission of radio | | | | signals. | | +-----------------------+-----------------------+-----------------------+ | 06 | Reginald Fessenden | Triode is also known | | | invented Amplitude | as Amplifier | | | Modulation (AM). | | | | | | | | Lee De Forest added a | | | | grid to the diode and | | | | produced triode. | | | | | | | | Ernst F. W. | | | | Alexanderson invented | | | | the Tuned Radio | | | | Frequency Receiver | | | | (TRF) an HF | | | | Alternator producing | | | | AC, contributing | | | | better voice | | | | broadcasting. | | +-----------------------+-----------------------+-----------------------+ | 18 | Edwin H. Armstrong | | | | invented the | | | | Superheterodyne | | | | Receiver. | | +-----------------------+-----------------------+-----------------------+ | 31 | Edwin Armstrong | | | | invented the | | | | Frequency Modulation, | | | | greatly improving the | | | | quality of the | | | | signals. | | +-----------------------+-----------------------+-----------------------+ | 45 | Arthur C. Clarke | Sputnik I -- 1^st^ | | | proposed the use of | active satellite | | | satellites for long | (came from Russia) | | | distance radio | | | | transmissions. | Moon -- 1^st^ passive | | | | satellite (does not | | | | use power) | +-----------------------+-----------------------+-----------------------+ | 46 | AT&T introduced the | Parang PLDT | | | first mobile | | | | telephone system for | | | | the public called the | | | | MTS (Mobile Telephone | | | | System). | | +-----------------------+-----------------------+-----------------------+ | 58 | Jack Kilby developed | | | | the first Monolithic | | | | Integrated Circuit | | | | Semiconductor chip | | | | with active and | | | | passive elements. | | +-----------------------+-----------------------+-----------------------+ | 67 | K. C. Kao and G. A. | Fiber optics -- a | | | Bockam of Standard | technology that uses | | | Telecommunications | light for | | | Laboratories in | transmission | | | England proposed the | | | | use of cladded fiber | Optical fiber -- it | | | cables as new | concerns about media | | | transmission medium. | (channel) | +-----------------------+-----------------------+-----------------------+ | 83 | Cellular telephone | | | | networks introduced. | | +-----------------------+-----------------------+-----------------------+ | 91 | Tim Berners -- Lee | | | | developed World Wide | | | | Web (WWW). | | +-----------------------+-----------------------+-----------------------+ **[Telegraph]** 1. **Samuel Morse** invented the telegraph (*Uses Morse Code*) in 1844. The telegraph is considered as the forerunner in *digital communications*. *( discrete two state)* It is a *variable-length code* using an alphabet of *4 symbols*: a dot, a dash, a letter space, and a word space. Notice that **short sequences** represent **frequent letters**. **[Telephone]** 1. **Alexander Graham Bell** invented the first telephone in 1875. The telephone made **real-time transmission of speech** by *electrical encoding and replication of sound* a practical reality. **[Electronics]** 1. In 1904, **John Ambrose Fleming** invented the *vacuum-tube diode*, which paved the way for the invention of the *vacuum-tube triode* by **Lee de Forest** in 1906. The *transistor (point contact transistor)* was invented in 1948 by **Walter H. Brattain, John Bardeen, and William Shockley** at Bell Laboratories. The *first silicon integrated circuit (IC)* was produced by **Robert Noyce** in 1958. **[5G Evolution Wireless communications]** ELECTRONIC COMMUNICATION **[Electronic Communication Systems]** (*x'msm/reception of information signal using electronic devices)* 1. The fundamental purpose of an electronic communications system is to **transfer information from one place to another**. All electronic communication systems have a *transmitter, a communication channel or medium, and a receiver*. **[Information Source]** 1. In electronic communication systems, the message is referred to as *information*, or an *intelligence signal*. The source of information could either be in **analog form** such as *human voice and music*, or in **digital form** such as *binary-coded numbers or alphanumeric codes*. - **Analog signals** are time-varying voltages or currents that are *continuously* changing. - **Digital signals** are voltages or currents that change in *discrete* steps or levels. 2. **[Transmitter]** 1. The first step in sending a message is to **convert** it into electronic form suitable for transmission. **Transducers** are used to *convert physical characteristics* (temperature, pressure, light intensity, and so on) into electrical signals. 1. Examples: 1. Voice messages -- microphone converts acoustic energy into an electric audio signal 2. Television -- camera sensor converts light information into video signals 3. Computer systems -- input devices (mouse, keyboard, etc.) converts mechanical energy into binary codes **[Transmitter (Tx)]** 1. The transmitter is a **collection of electronic components and circuits** designed to convert the electrical signal to a signal suitable for transmission over a given communication medium. Transmitters are made up of *oscillators, amplifiers, tuned circuits, filters, modulators, frequency mixers, frequency synthesizers, and other circuits*. **[Communication Channel or Transmission Media]** 1. The communication channel is the medium by which the electronic signal is sent from one place to another. It can either be a **guided channel** by using *wire conductors, fiber-optic cable, or waveguides,* or **unguided channel** when signals are transmitted over *free space*. Guided channels are also called **wireline channels,** while unguided channels are called **wireless channels**. **[Communication Channel]** ***Wireline Channel*** Electronic conductors -- examples include *coaxial cables* for TV, *twisted-pair cables* used in a local area network (LAN) Optical media - *fiber-optic cable* or *light pipe* that carries the message on a light wave ***Wireless Channel*** Free space -- when free space is the medium, the resulting system is known as **radio**. Acoustic -- *underwater communication* Optical -- through *infrared* such as *remote control*. **[Receiver (Rx)]** 1. A receiver is a collection of electronic components and circuits that accepts the transmitted message from the channel and *converts it back to a form understandable by humans*. Receivers contain *amplifiers, oscillators, mixers, tuned circuits, filters, and demodulator* that recovers the original intelligence signal from the modulated carrier. The main objective is to **retrieve the transmitted signal** at the receiver end. **Noise** 1. Noise refers to **unwanted signals** that tend to *disturb the quality of the received signal* in a communication system. The sources of noise may be *internal or external* to the system. The **measure of noise** is usually expressed in terms of the **signal-to-noise ratio (SNR)**, which is the signal power divided by the noise power and can be stated numerically as  **[Types of Electronic Communication]** Electronic communications are classified according to whether they are: 1. One-way (simplex) or two-way (half duplex or full duplex) transmissions 2. Analog or digital signals 3. Baseband or Modulated Signals +-----------------------------------+-----------------------------------+ | ***One way*** | ***Two way*** | +===================================+===================================+ | [One-way: | **[Two-Way or Duplex: Half | | **Simplex**] | Duplex]** | | | | | 1. The simplest method of | **The form of two-way | | electronic communication is | communication in which only one | | referred to as **simplex**. | party** | | | | | **This type of communication | **transmits at a time is known as | | is one-way**. Examples are: | half duplex. Examples are:** | | | | | - AM and FM Radio broadcasting | - **Police, military, etc. | | | radio transmissions** | | - TV broadcasting | | | | - **Citizen band (CB)** | | - Beeper (personal receiver) | | | | - **Amateur radio** | | | | | | [Two-Way or Duplex: **Full | | | Duplex**] | | | | | | When people can talk and listen | | | simultaneously, it is called full | | | duplex. The telephone is an | | | example of this type of | | | communication. | +-----------------------------------+-----------------------------------+ **[Types of Electronic Communication]** +-----------------------------------+-----------------------------------+ | ANALOG SIGNALS | DIGITAL SIGNALS | +===================================+===================================+ | An analog signal is a smoothly | Digital signals change in steps | | and continuously varying voltage | or in discrete increments. | | or current. Examples are: | | | | Most digital signals use binary | |  | or two-state codes. | | | | | | Examples are: | | | | | | - Telegraph (Morse code) | | | | | | - Continuous wave (CW) code | | | | | | - Serial binary code (used in | | | computers) | | | | | | Many transmissions are of signals | | | that originate in digital form | | | but must be converted to analog | | | form to match the transmission | | | medium. | | | | | | - Digital data over the | | | telephone network. | | | | | | - Analog signals. | | | | | | They are first digitized with an | | | analog-to-digital (A/D) | | | converter. | | | | | | The data can then be transmitted | | | and processed by | | | | | | computers and other digital | | | circuits | +-----------------------------------+-----------------------------------+  +-----------------------------------+-----------------------------------+ | BASEBAND SIGNALS | MODULATED SIGNALS | +===================================+===================================+ | Baseband signal refers to the | To transmit baseband signals by | | information signal, regardless of | radio *(wireless)*, modulation | | whether it is analog or digital. | technique must be used. | | | | | *unmodified signal (NO | A radio-frequency (RF) wave, or | | modulation)* | radio wave, is an | | | | | *Audio signal to electrical | electromagnetic signal that is | | signal, amplifies sound, back to | able to travel long distances | | audio signal. NO modulation* | through space. | | | | | *Example: Lapel* | Modulation is the process of | | | having a baseband voice, video or | | | | | | digital signal modifies another, | | | high-frequency signal called the | | | | | | carrier. | +-----------------------------------+-----------------------------------+ **[Modulation and Multiplexing]** ***Baseband Transmission*** **Baseband** information can be sent directly and unmodified over the medium or can be used to modulate a carrier for transmission over the medium. - In telephone or intercom systems, the voice is placed on the wires and transmitted. - In some computer networks, the digital signals are applied directly to coaxial or twisted-pair cables for transmission. ***Broadband Transmission*** A broadband transmission takes place when a carrier signal is modulated, amplified, and sent to the antenna for transmission. The two most common methods of modulation are: - Amplitude Modulation (AM) - Frequency Modulation (FM) Another method is called phase modulation (PM), in which the phase angle of the sine wave is varied. 3. 2.