SFWRENG 4J03 Lecture Notes - Lecture 6: Angle Modulation, Mathtype, C Mathematical Functions
12 Oct 2016
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Document Summary
One of the ways to modulate the angle of a carrier. Frequency of a carrier is related to the instantaneous amplitude of the message signal. I(t) = 2 fct + 2 kf m t t d t. = fc + f cos(2 fmt) instantaneous angle of the modulation signal [fi]: multiply by 2 and integrate to get fi(t) [ f]: change with respect to original carrier frequency, kpam. Carrier frequency will be varied by f fc + f fc f. 2 f t c m sin 2 f t m sin 2 f t m. A c f t c f t m sin 2 cos 2. Narrow band frequency modulation (nbfm): << 1 rad bandwidth is finite. Wide band frequency modulation (wbfm): >> 1 rad bandwidth is very large, identify infinity bandwidth = upper sideband lower sideband = 2fm. Multi-tone modulation: multiple message signals (practical, since air is common medium) frequency transmission better for audio signals.
