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Homework 9 - Angular Transmission Modulation

Problem 1.
If a frequency modulator produces 5KHz of frequency deviation for a 10V modulating signal, determine the deviation sensitivity. How much frequency deviation is produced for a 2V modulating signal.
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Problem 3.
Determine (a) the peak frequency deviation, (b) the carrier swing, and (c) the modulation index for an FM modulator with deviation sensitivity K1 = 4KHz/V and a modulating signal vm(t) = 10 sin( 2 pi 2000 t ). What is the peak frequency deviation produced if the modulating signal were to double in amplitude?
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Problem 7.
For an FM modulator with modulation index m = 2, modulating signal vm(t) = Vm sin ( 2 pi 2000 t), and an unmodulated carrier vc(t) = 8 sin (2 pi 800 kt), determine the following:
a) The number of sets of significant sidebands
b) Their amplitudes
c) Draw the frequency spectrum showing the relative amplitudes of the side frequencies
d) The bandwidth
e) The bandwidth if the amplitude of the modulating signal increases by a factor of 2.5.

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Problem 10.
An FM transmitter has a rest frequency equal to 96MHz and a deviation sensitivity K1 = 4KHz/V. Determine the frequency deviation for a modulating signal vm(t) = 8 sin ( 2 pi 2000 t), and the modulation index.
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Problem 12.
For an FM modulator with a 40KHz frequency deviation and a modulating signal frequency of 10KHz, determine the bandwidth using both a Bessel table and Carsonís rule.
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Problem 13.
For an FM modulator having an unmodulated carrier amplitude Vc = 20V, a modulation index m = 1, and a load resistance RL = 10ohms, determine the power in the modulated carrier an each side frequency, and sketch the power spectrum for the modulated wave.
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Homework Solutions and Calculations

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Engineering key words: modulation, RF spectrum, power and gain, waveform, Bessel table, Carsons Rule, amplitude, bandwidth, sideband, frequency deviation, sensitivity, FM, loads, signals, angular modulation, phase angle, transmit.

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