Engr. Jaime P. Licuanan, CCNA
CHAPTER 1 :Introduction to Electronic Communications
the transmission, reception and processing of information between two or more locations using electronic circuits signals that are time-varying voltages or currents that are continuously changing, such as cosine and sine waves. It contains an infinite number of values signals that are voltages or currents that change in discrete steps or levels he invented the first workable telegraph it is used to transfer information in the form of dots, dashes and spaces between a simple transmitter and receiver using a transmission line consisting of a length of metallic wire they were the first to successfully transfer human conversation over a crude metallic-wire communication system using a device they called telephone a logarithmic unit that can be used to measure ratios of virtually anything a transmission-measuring unit used to express relative gains and losses of electronic devices and for describing relationships between signals and noise another name for power loss a collection of one or more electronic devices or circuits that converts the original source information to a form more suitable for transmission over a particular transmission medium it provides a means of transporting signals between a transmitter and a receiver and can be as simple as a pair of copper wires any unwanted electrical signals that interfere with the information signal a collection of electronic devices and circuits that accepts the transmitted signals from the transmission medium and then converts those signals back to their original form higher-frequency analog signal the process of changing one or more properties of the analog carrier in proportion with the information signal a system in which energy is transmitted and received in analog form, both the information and the carrier are analog signals electronic communications analog signals
digital signals Samuel Finley Breese Morse (1837) electromagnetic induction
Alexander Graham Bell Thomas A. Watson decibel (dB) decibel attenuation transmitter transmission medium or communications channel system noise receiver carrier modulation Analog system communication
Electronics Systems and Technologies
Engr. Jaime P. Licuanan, CCNA
it covers a broad range of communication techniques including digital and digital radio a true digital system where digital pulses are transferred between two or more points in communication system the transmittal of digitally modulated analog carriers between two or more points in communication system the information signal is analog and the amplitude of the carrier is varied proportional to the information signal the frequency is varied proportional to the information signal a circuit performing modulation in a transmitter a carrier that has been acted on by an information signal the reverse process of modulation and converts the modulated carrier back to the original information it is often used to refer to a specific band of frequencies allocated a particular service another name for information signal the process of converting a frequency or band of frequencies to another location in the total frequency spectrum it can propagate as a voltage or current along a metallic wire as emitted radio waves through free space or as light waves down an optical fiber simply the number of times a periodic motion such as sine wave of voltage or current occurs in a given period of time an international agency in control of allocating frequencies and services with the overall frequency spectrum signals in the 30-Hz to 300-Hz range and include ac power distribution signals (60Hz) and low frequency telemetry signals signals in the 300-Hz to 3000-Hz range and include frequencies generally associated with human speech, standard telephone channels signals in the 3-kHz to...