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8 Cards in this Set
- Front
- Back
modulation
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converts a digital computer signal into a form that can travel down an ordinary analog telephone line (e.g.: analog to digital, etc); carry waves
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forms of modulation
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◦ Amplitude modulation
◦ Frequency modulation ◦ Phase modulation ◦ Quadrature amplitude modulation (QAM) -- combines amplitude and phase modulation |
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Amplitude Modulation (AM)
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frequency stays the same, but amplitude changes
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amplitude
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the intensity of the signal.
◦ Loud (1) or soft (0) |
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Frequency Modulation (FM)
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amplitude stays the same, but frequency changes
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frequency
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number of complete cycles per second; measured in Hertz - kHz, MHz, GHz, THz; higher frequency = shorter wavelength
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Phase Modulation (PM)
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signals can have same frequency & amplitude, but different phases; be at different points in cycles at a given moment; harder to understand than FM & AM, but sensitive to equipment
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Quadrature Amplitude Modulation
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uses 2 carrier waves -- sine and cosine (90 degrees out of phase) -- both amplitude modulated
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