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Digital modulation methods can be considered as digital-to-analog conversion and the corresponding demodulation or detection as analog-to-digital conversion. The changes in the carrier signal are chosen from a finite number of M alternative symbols (the modulation alphabet). Schematic of 4 baud, 8 bit/s data link containing arbitrarily chosen ...
Demodulation is the process of extracting the original information-bearing signal from a carrier wave. A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated carrier wave. [1] There are many types of modulation, and
A modulator-demodulator, commonly referred to as a modem, is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio.
In analog frequency modulation, such as radio broadcasting, of an audio signal representing voice or music, the instantaneous frequency deviation, i.e. the difference between the frequency of the carrier and its center frequency, has a functional relation to the modulating signal amplitude.
The modulator is then programmed to broadcast the signals on a certain frequency. That RF broadcast is then received by the connected TV. When the TV is tuned to the programmed channel, the video and audio signal of the source device is accessed. RF modulation can become difficult in a CATV system. High pass, low pass, and notch filters must be ...
where is the energy per symbol in joules and ρ is the nominal spectral efficiency in (bits/s)/Hz. [2] / is also commonly used in the analysis of digital modulation schemes. The two quotients are related to each other according to the following:
[1] [2] [3] Heterodyning is used to shift signals from one frequency range into another, and is also involved in the processes of modulation and demodulation. [ 2 ] [ 4 ] The two input frequencies are combined in a nonlinear signal-processing device such as a vacuum tube , transistor , or diode , usually called a mixer .
E represents the envelope term; roughly half the modulation term applied to the envelope modulator is utilized to reduce the second-order term of the arcsin "phase"-modulated path; thus reducing the second-order term in the undesired sideband. A multi-loop modulator/demodulator feedback approach was used to generate an accurate arcsin signal.