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Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave.In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal.
3.1 Amplitude modulation. 3.2 Frequency modulation. ... Internal electronic noise of measurement systems can be reduced through the use of low-noise amplifiers.
Telecommunication systems strive to increase the ratio of signal level to noise level in order to effectively transfer data. Noise in telecommunication systems is a product of both internal and external sources to the system. Noise is a random process, characterized by stochastic properties such as its variance, distribution, and spectral density.
Categorization for signal modulation based on data and carrier types. In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a separate signal called the modulation signal that typically contains information to be transmitted. [1]
QAM is used extensively as a modulation scheme for digital communications systems, such as in 802.11 Wi-Fi standards. Arbitrarily high spectral efficiencies can be achieved with QAM by setting a suitable constellation size, limited only by the noise level and linearity of the communications channel. [ 1 ]
A 'signal space diagram' is an ideal constellation diagram showing the correct position of the point representing each symbol. After passing through a communication channel, due to electronic noise or distortion added to the signal, the amplitude and phase received by the demodulator may differ from the correct value for the symbol. When ...
The frequency spectrum of a typical radio signal from an AM or FM radio transmitter. The horizontal axis is frequency; the vertical axis is signal amplitude or power. It consists of a signal (C) at the carrier wave frequency f C, with the modulation contained in narrow frequency bands called sidebands (SB) just above and below the carrier.
After pulse compression, the signal-to-noise ratio can be considered as being amplified by as compared to the baseline situation of a continuous-wave pulse of duration ′ = / and the same amplitude as the chirp-modulated signal before compression, where the received signal and noise have (implicitly) undergone a bandpass filtering on [/, + /].