October 2013
Intermediate to advanced
400 pages
10h 16m
English
We've examined AM transmission. Now the discussion turns to frequency modulation (FM). This scheme simplifies video transmission in some ways, while complicating it in other ways.
Frequency modulation uses the instantaneous amplitude of a modulating signal (voice, music, data, etc.) to directly vary the frequency of a carrier signal. Modulation index beta (β) describes the ratio of maximum frequency deviation of the carrier to the maximum frequency deviation of the modulating signal.
In an intensity-based system, the modulation index measures how much the modulation signal affects the light output. To determine this value, let the carrier be xc(t) = Ac•cos ( ...