An oscillator is an electronic device for generating an AC signal voltage. Oscillators generate sinusoidal or non-sinusoidal waveform from very low frequencies up to very high frequencies. Read more about Oscillators
Telegraphy is used to transfer information in the written form. It is a combination of two words. "Tele" means at a distance and "Graph" means to write. Hence telegraphy is to write at a distance.
The transmission media used for the communication of signals from one point to another are copper wires, coaxial cables, wave-guides and radio links. Read more about Optical Fiber
Morse code is named in honor of Samuel F.B. Morse, an American who invented the telegraphic code. The morse code basically consists of two elements, the dot (.), called "dit", which is the shortest element
Machine telegraphy started with the 5-unit code system and worked very well. However, the matching of the sending and receiving mechanism was very critical.
Exchange is a central place through which one telephone can be connected to any other telephone indirectly. A large number of telephone lines are interconnected with each other through the exchange.
The telephone system is an arrangement of electrically interconnected transmitters and receivers, by means of which speech is communicated between two points, either close together or remote
Microwave refer to high frequencies (above 300MHz) and short wave lengths, at the microwave components depends on the changing electro magnetic fields instead of current in the conductor or voltage across the 2 points a microwave propagated through the line of sight Read more about Microwave Communication
