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Question 1

Trans and reception of information signal thru electronic device

Answer 1

Electronic Comms

Question 2

Converts into signal that is suitable to channel
Must be properly modulated

Answer 2

Transmitter

Question 3

Can be guided or unduided

Answer 3

Channel

Question 4

T.p wire
Coaxial cable} uses electrical signal
Optical fiber- uses light energy

Answer 4

Guided medi

Question 5

Uses free space, e.m wave

Answer 5

Unguided media

Question 6

Categories of Electronic communications

Answer 6

1. One way/ simplex & Two way/ duplex
2. Analog & Digital
3. Baseband & Broadband

Question 7

Represents the principal reason for using analog to analog modulation

Answer 7

Because Higher frequency is needed for effective transmission

Question 8

Bandwidth required for a modulated carrier depends on

Answer 8

Baseband frequency range

Question 9

Bandwidth of analog signal contains most of its power ( or energy)

Answer 9

Effective bandwidth

Question 10

Range of frequency allow to pass thru without distortion

Answer 10

Channel bandwidth

Question 11

Value

Answer 11

Absolute bandwidth

Question 12

No Intersymbol Interference, flat fading

Answer 12

Coherence bandwidth

Question 13

Sending the signak at high frequencies

Answer 13

Passband transmission

Question 14

For low frequency

Answer 14

Baseband transmission

Question 15

Process, characteristics of wVe are varied in accordance with a message

Answer 15

Modulation

Question 16

Rate of change
Number of cycles taken by EM waves in one second

Answer 16

Frequency

Question 17

Distance traveled bt EM wave in one cycle

Answer 17

Wavelength

Question 18

Time taken by EM wave to complete one cycle

Answer 18

Period

Question 19

Voice grade channel

Answer 19

300Hz - 3,400Hz

Question 20

Voice channel bandwidth

Answer 20

4Hz

Question 21

Two or more signals share a commnon channel

Used to efficiently transfer signal from one point to another

Answer 21

Multiplexing

Question 22

m = 1

Answer 22

Ideal

Question 23

m > 1

Answer 23

Over modulation

Question 24

m &laquo_space;1

Answer 24

Under modulation

Question 25

m < 1

Answer 25

Practical

Question 26

The power in the sidebands in AM system depends on

Answer 26

Modulation index

Question 27

Application of a mixer of a signal from a local oscillator at a freq. below that of the incoming signal

Answer 27

Low side injection

Question 28

Modulation as stage earlier than final stage Uses linear amplitude ( A, B, AB)

Answer 28

Low-level modulation

Question 29

Modulation at final stage Uses class C amplitude due to high efficiency

Answer 29

High-level modulation

Question 30

It suppress carrier

Answer 30

Balanced modulator

Question 31

Not used bec. it's difficult to demodulate It requires sync for both phase and frequency

Answer 31

DSBSC

Question 32

Ssb generator types

Answer 32

Filter method- most used Phasing method-cuses 2BM & 2 phase shifter Third (weaver)- combines 1 & 2

Question 33

Advantages of SSB over AM (DSBFC)

Answer 33

Spectrum utilization Less bandwidth Less power Less fading

Question 34

In SSB____ is simply the DC input power of the final ampli. stage at the instant voice envelope peak

Answer 34

Peak envelope power (PEP)

Question 35

Double sideband suppressed carrier modulation requires the carrier to be reinserted at the receiver with the correct phase and frequency. Single sideband suppressed carrier modulation only requires the ____ of the inserted carrier to be correct

Answer 35

Frequency

Question 36

Additional side freq. produced by overmodulation or distortion in any AM system is known as

Answer 36

Sideband splatter

Question 37

Emission outside the assigned BW

Answer 37

Spurious signal

Question 38

In transmitter system, the absence of spurious signals refers to

Answer 38

Spatial purity

Question 39

Two main characteristics of receiver

Answer 39

Sen-sel

Question 40

Ability of the receiver to process every weak signal (SNR)

Answer 40

Sensitivity

Question 41

Ability of the receiver to reject unwanted freq.

Answer 41

Selectivity

Question 42

Faithful reproduction of signal

Answer 42

Fidelity

Question 43

The greater the number of tuned circuits, ____

Answer 43

The higher the Q

Question 44

The narrower the passband, ____

Answer 44

The higher the selectivity

Question 45

PM Carrier freq is proportional to both ____ and ____

Answer 45

Amplitude and Freq

Question 46

PM Max. phase shift and max carrier freq occurs at ___ crossing point of modulating signal

Answer 46

Zero

Question 47

FM Carrier freq. is propotional only to ____ of modulating signal

Answer 47

Amplitude

Question 48

As freq. mod is varied,

Answer 48

m is also varied

Question 49

In phase mod, the carrier freq. deviation is propotional to ____

Answer 49

Both modulating freq and amplitude of the modulating signal

Question 50

When the modulating signam amplitude crosses zero, the phase shift and freq dev in a phase mod ____

Answer 50

Are at maximum

Question 51

When the modulating freq is changed the PM mod index ____

Answer 51

Remain constant

Question 52

Advantages of FM over AM

Answer 52

Noise immunity Capture effect Transmitter efficiency

Question 53

Tendency of an FM receiver to receive the strongest signal and reject others

Answer 53

Capture effect

Question 54

Ability of receiver to reject unwanted freq

Answer 54

Selectivity

Question 55

Ability of receiver to still process weak signal

Answer 55

Sensitivity

Question 56

In adjacent channel, where the sensitivity of one channel is reduced by another (decentralisation(

Answer 56

Blocking

Question 57

A pre-emphasis circuit provides extra noise immunity by

Answer 57

Amplifying the higher audio freq.

Question 58

Due to practical reason, bandwidth of FM trans is generally limited by government regulations by putting limits on:

Answer 58

Max freq dev and max mod freq