Question

Q.N. 1:- Frequency modulation (FM) and Phase modulation (PM) are both considered angular modulation techniques. As such, you can modulate using FM, and demodulate the received signal using PM.

True

False

Q.N. 2:-

Select the correct statement(s) regarding frequency modulation (FM).

		a. baseband amplitude changes (information) are captured as carrier wave frequency changes
		b. a device such as the voltage controlled oscillator (VCO) is required to convert signal amplitude changes to changes in frequency
		c. the more the carrier frequency is allowed to change (i.e., Δf), the greater the bandwidth as seen in the frequency domain
		d. all of the above are correct statements

Q.N. 3:-

What are the units of the FM Kvco?

		a. radians per Hertz
		b. Hertz per volt
		c. volts per Hz
		d. Hertz per radians

Q.N. 4:-

Select the correct statement(s) regarding the FM Index.

		a.  Δf represents the amount of frequency that the carrier wave can change in order to represent the baseband (information/message) signal
		b. β=(KvcoAm)/fm  is a ratio that has no units
		c. the larger the FM index, the greater the frequency bandwidth
		d. all statements are correct

Q.N. 5:-

Given the following FM modulated signal equation, determine the original message equation, m(t). s(t)= 1.8cos(2π2.4GHz*t + 3sin(2π22kHz*t)), Kvco=4500 (Hz/v)

		a. m(t)= 1.8cos(2π2.4E9t)
		b. m(t)= 1.8cos(2π22E3t)
		c. m(t)= 14.7cos(2π22kHz*t)
		d. m(t)= 3cos(2π13E3t)

Answer 1

1 Ans : false

The relationship between phase and frequency variations is not linear;that is, phase and frequency do not vary in direct proportion.

2. Ans:

d: All the above statements are correct

3. Ans

b.Hertz per volt

Kvco is VCO’s frequency/voltage gain in unit of Hz/V.

4. Ans :c. the larger the FM index, the greater the frequency bandwidth

BW = 2 (β + 1 ) f_m

_where:

where β  is the modulation index and

f_m is the maximum modulating frequency used.