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Electronic Communications
Published in Dale R. Patrick, Stephen W. Fardo, Electricity and Electronics Fundamentals, 2020
Dale R. Patrick, Stephen W. Fardo
Continuous-wave (CW) communication is the simplest of all communication systems. It consists of a transmitter and a receiver. The transmitter employs an oscillator for the generation of an RF signal. The oscillator generates a continuous sine wave. In most systems the CW signal is amplified to a desired power level by an RF power amplifier. The output of the final power amplifier is then connected to the antenna-ground network. The antenna radiates the signal into space. Information or intelligence is applied to the CW signal by turning it on and off, which causes the signal to be broken into a series of pulses or short bursts of RF energy. The pulses conform to an intelligible code. The international Morse code is in common usage today. Figure 7-5 shows a simplification of the Morse code. A short burst of RF represents a dot. A burst three times longer represents a dash. Signals of this type are called keyed or coded continuous waves. The Federal Communications Commission (FCC) classifies keyed CW signals as type Al. This is considered to be radio telegraphy with on-off keying. Figure 7-6 shows a comparison between a CW signal and a keyed CW signal.
Information
Published in Philipp Kornreich, Mathematical Models of Information and Stochastic Systems, 2018
An early information transmission system was the Morse code system. It was patented in 1854 by Samuel Morse. Samuel Morse was born in 1791 in Charleston, Massachusetts, and passed away in 1872 in New York City. Before he developed his code, he was a professor of sculpture and painting at New York University. The Morse code is used to this day, especially in emergency situations, because it requires very little bandwidth for transmission. A manually operated Morse code communication system requires a bandwidth of about 1 Hz.
The Role of Artificial Intelligence for Network Automation and Security
Published in Mazin Gilbert, Artificial Intelligence for Autonomous Networks, 2018
Although early evidence of communication was observed in Africa, the Americas, and China through the use of smoke signals and drums, the real breakthrough happened in the nineteenth century through the invention of the electric telegraph by Francis Ronalds [1]. The telegraph was the first communication network of its kind that enabled short-distance transmission of signals. In 1837, Samuel Morse, along with his assistant Alfred Vail [2], invented the Morse code for transmission of information across an electric telegraph. The telegraph used a transmitter, in the form of a sending device or encoder, which enabled sending a series of dots and dashes to represent letters and characters. At the receiving end, a decoder was used to receive the information that was then interpreted by an operator.
The Changing Face of Public Broadcasting in India
Published in IETE Journal of Education, 2023
Pioneering initial work by Heinrich Hertz and J C Bose was soon followed by the invention of wireless communication by Gugliemo Marconi and more development by Popov in Russia towards the end of nineteenth century. These events taken all together have paved the way for transmission of information at long distances by means of radio frequency (RF) electromagnetic waves, without the need for any physical connecting medium. In the beginning, information could only be transmitted in the presence or absence of RF signal, called keying. The long and short burst of RF energy was coded by the famous Morse code, already used in telegraphy, to represent alphabets and thereby intelligible sentences could be reconstructed at the receiving end. The possibility of continuous variation of the amplitude of the RF wave, called carrier, and subsequent extraction of the amplitude variation at the receiving end, made possible the transmission of voice signals over long distances by means of radio waves. The radio stations transmitting voice and music programs over the air came into being, heralding the birth of public broadcasting.