Republic of the Philippines

CAGAYAN STATE UNIVERSITY

Carig, Tuguegarao City

COLLEGE OF ENGINEERING

Finalterm Examination
Principal in communication
set A 2nd SEM S.Y. 2020-2021

Name:________________________________ Course:_________________ Score:_________

MULTIPLE CHOICE: Write the letter of your answer in the space provided before each number.
Use CAPITAL LETTERS only. Do not use pencil.. STRICTLY NO ERASURES

1 Another term for amplitude modulation

a DSBFC b. SSBSC C. DSBSC D.PCM
2 In PM , carrier Frequency deviation is not proportional to?
a.Modulating signal amplitude b. Carrier amplitude and frequency
c.Modulating Signal Frequency d. Modulator phase shift
3 What must be the value of the modulation index in order to achieve NBFM
a. .25 b..5 c.1 d. 2
4 The main purpose of 19 KHz pilot in stereo multiplexed signal in FM is for the reciever to ____ ?
a. Indicate stereo reception b.Demodulation
c.Modulation d. Multiplexing
5 In th microwave communication, the frequency range oof super high frequency is_________ MHz?
a. 30- 300 b. 300-3000 d.3000-30,000 d. 30,000- 3000,000
6 The information of an AM signal resides in the?
a. Upper side bands b. Lower side bands
c. Upper and lower side bands d. carrier signal
7 Morse code is a form of:
A. Digital modulation. C. Phase modulation.
B. Analog modulation D. dc modulation.
8 The amount of frequency shift during modulation is called the _____.
a. Amplitude b. Frequency c. Phase shift d deviation
9 In PM, the carrier _____ is varied in proportion to the amplitude of the modulating signal.
a.phase shift b. Amplitude
c. frequency d. QUAM
10 what is the BW of a commerial FM
a. 200 KHz b. 200Mhz c. 200Ghz d. 200 THz
11 Noise is primarily a variation in
a. Amplitude b. Frequency. c. Phase. d. Quam
12 A phase modulator may use a low-pass filter to offset the effect of increasing carrier frequency
deviation for increasing modulating
a. Amplitude b. Frequency c. Phase shift d QUAM
13 Luminance signal in Television is
a. .30R+.59G+.11B b. .60R-0.28-.32B c. .21-52G +.31B
14 The method used to offset the effect of noise in FM transmissions by boosting high frequencies is
known as _____.
a. capture effect b.limiter (or clipper) c.pre-emphasis d. de-emphasis
15 The FM produced by a phase modulator is known as _____.
a. FM b. fm c.indirect FM d. fc
16 the voice Frequency channel pass band is
a. 0-4000 c. To carry speech C. 155 kHz. D. 1.55 MHz.
17 The amount of frequency shift during modulation is called the _____.
a. Amplitude b. Frequency c. Phase shift d deviation
18 then ability of the radio reciever to separate or pick out desire signal and tuned out the rest or unwanted signal
a. sensitivity b. fidelity c. Selectivity d. Capture Effect
19 The Standard Intermsdiate Frequency ( IF) of an FM transmitter is______?
a. 455KHz b.10.7Mhz c. 200MHz
20 Iif the amplitude of the modulating signal applied to phase modulator is constant, the output signal will be?
a.zero b. the carrier frequency c. Above the carrier Frequency d. Below the carrier frequency
set A
21 speaker phones operates in
a. simplex b. Duplex
c. Full duplex d. Full- full duplex
22 In amplitude modulation, Bandwidth is ______ the audio freq.?
a. 4x b. 3x c. 2x d.5x
23 the tranmission and reception of an information is called
a. Modulation b. Communication c. radiation d. Emission
24 Pre- empahsis and deemphsis are used in a FM multiplex system to improve _______?
a. Standing wave ratio b. Power ratio
c. signal to noise ratio c. Voltage ratio
25 The bandwidth of an FM signal is proportional to the _____.
a. frequecy b.modulation index c, amplitude
26 The reciever circuit that rids FM noise is the
a. Modulator b. Demodulator c. Limiter d. LPF
27 The primary dis advantage of FM is its
a. Higher cost and complexity b. Excessive use of spectrum space
c. capture effect d. Noise Suceptibility
28 The maximum allowed deviation of FM sound signal in TV is 25khz
. If the actual deviation is 18Khz, the percent modulation is?
a. 43% b. 72 % c. 96% d. 139%
29 An FM transmmiter has a maximum deviation of 12 Khz and
maximum modulation frequency of 12 Khz . The Bandwidth by Carson's rule is?
a. 24 KHz b.33.6KHz c.36.8 KHz d. 48 KHz
30 over modulation results in
a. weekening of signal b. excessive carrier power c, distortion

II Draw and explain( 5pts)

1 The Frequency Spectrum and its application
2 Difference between amplitude ,Phase and Frequency Modulation
3 What is envelop in AM and show how this is created.

III. Solve( 5 pts each)

1 If the maximum allowed deviation is 5 kHz but the actual deviation is 3.75 kHz, the percentage of
modulation is _____ percent.

2 An FM transmitter has a rest frequency Fc=96 MHz and deviation sensitivity K1= 4KHz/V.
Determine the frequency deviation for a modulating signal Vm(t)= 8 sin (2π2000t).
Detertime modulation index and BW( realistic)
Solve and draw the folloing having VC=1 assume your own VM
3 Over Modulation
4 100 % modulation
5 under modulation

Prepared by: Approved By:

Engr. Pinky C. Tumaliuan Engr. Audy R. Quebral

Prof IV Dean , College of Engineering