CALCULATION QUESTIONS (AM Modulation Fundamentals)
1. An AM wave has a peak modulation voltage, Vm of 1.5 V and a peak carrier voltage Vc of 4.0 V. Compute the modulation index, m and percentage modulation index M.
2. An AM signal has the equation v(t) = [15 + 4 sin (44 x 103t)] sin (46.5 x 106 t) V
a. find the carrier frequency
b. find the frequency of the modulating signal
c. find the value of modulation index
3. For an envelope with +Vmax = 40 Vp, and +Vmin = 10 Vp, determine
a. The unmodulated carrier amplitude
b. The peak change in amplitude of the modulated wave
c. The modulation coefficient
d. The percent modulation
4. For an unmodulated carrier amplitude Vc = 16 Vp and a modulation coefficient m = 0.4, determine the amplitudes of the carrier and side frequencies.
5. For a modulation coefficient m = 0.2 and a peak carrier power Pc = 1000 W,
determine
a. The sideband power
b. The total transmit power
6. Describe the meaning of the following expression
vam(t) = Vc sin(2πfct) - mVc/2 cos[2π(fc + fm)t] + mVc/2 cos[2π(fc - fm)t]
7. The radio station produced amplitude modulation wave as shown in figure below. The value of load at antenna is 50Ω.
Determine:
i. Equation for carrier signal
ii. Equation for information signal
iii. Equation for modulated signal
iv. Modulation index
v. Amplitude and frequency of upper side band