Question No. 2: The figure below shows the block diagram of a WBFM generator
using the indirect Armstrong method. The modulating signal m(t) is a sinusoidal with
frequency 50 Hz. At each stage of Armstrong frequency modulator find the carrier
frequency fc, the frequency deviation, the modulation index, n1, n2, and fo.
m(t )
f c1  0.1MHz

NBFM
Modulator
1
f1  25Hz
f c1  0.1MHz
f c 3  2.2 MHz
f c2
 n1
2
3
Mixer
f 3
f 2  1.6 KHz
f0
Oscillator
Oscillator
1
0.5
n1
64
2
32
fc2
6.4MHz
f
8.6Mhz
3
32
f 3
1.6Khz
n2
64
fc4
140.8Mhz
f 4
102.4Khz
 n2
f c4
 4  2048
f 4