LEC 3

Question 1

defined as anything that can carry information from a source to a destination

Answer 1

transmission media

Question 2

guided transmission media
examples:
twisted-pair cable
coaxial cables
fiber optic cables

Answer 2

wired

Question 3

unguided transmission media

Answer 3

wireless

Question 4

consists of two conductors, each with its own plastic insulation, twisted together

Answer 4

twisted-pair cable

Question 5

coax has a central core conductor of solid or stranded wire enclosed in an insulating sheath, encased in an outer conductor

Answer 5

coaxial cable

Question 6

made of glass or plastic that transmits signals in the

form of light

Answer 6

fiber optic cable

Question 7

transport electromagnetic waves without using a physical conductor

Answer 7

unguided media

Question 8

• Frequency range from 3KHz to 1GHz
• omnidirectional
• multicasting

Answer 8

radio wave

Question 9

• frequency ranges from 1GHz to 100GHz
• unidirectional
• unicasting

Answer 9

microwave

Question 10

• frequency ranges from 300THz to 400THz

- short range communications

Answer 10

infrared

Question 11

continuous

eg. analog clock, human voice

Answer 11

analog data

Question 12

discrete

eg. digital clock, information from computer

Answer 12

discrete

Question 13

___ infinitely many levels

of intensity over a period of time

Answer 13

analog signal

Question 14

___ have a limited number of defined values (1 and 0)

Answer 14

digital signal

Question 15

___completes a pattern within a measurable time frame (period)

Answer 15

periodic signal (analog)

Question 16

_____ changes without exhibiting a pattern or cycle that repeats over time – can represent variation in data

Answer 16

non-periodic signal (digital)

Question 17

most fundamental form of a periodic analog signal is the sine wave

Answer 17

sine wave

Question 18

classified as simple or composite

Answer 18

periodic analog signal

Question 19

the absolute value of its highest intensity, proportional to the energy it carries

Answer 19

peak amplitude

Question 20

refers to the amount of time a signal needs to complete one cycle;

Answer 20

period

Question 21

refers to the number of

periods in one second

Answer 21

frequency

T = 1/F

Question 22

describes the position of the waveform relative to time 0

Answer 22

phase

Question 23

binds the period or the frequency of a simple sine wave to the propagation speed of the medium (λ= cT= c/f)

Answer 23

wavelength

Question 24

any composite signal is a combination of simple sine waves with different frequencies, amplitudes, and phases

Answer 24

fourier analysis

Question 25

Any periodic signal can be represented as a sum of sinusoids known as a _____

Answer 25

Fourier Series

Question 26

can be decomposed into a series of simple sine waves with discrete frequencies

Answer 26

periodic composite signals

Question 27

can be decomposed into a combination of an infinite number of simple sine waves with continuous frequencies

Answer 27

nonperiodic composite signals

Question 28

difference between the highest and the lowest frequencies contained in a composite signal

Answer 28

bandwidth

Question 29

T/F | if a signal has L levels, each level needs log2L bits

Answer 29

T

Question 30

used to describe digital signals – the number of bits sent in 1 second

Answer 30

bit rate

Question 31

the distance one bit occupies on the transmission medium

Answer 31

bit length

Question 32

bit length = propagation speed x bit duration

Answer 32

--------

Question 33

2 TRANSMISSION OF DIGITAL SIGNALS

Answer 33

baseband transmission | low pass channel

Question 34

sending a signal over a channel without changing | the digital signal to an analog signal

Answer 34

baseband transmission

Question 35

a channel with a bandwidth that starts from zero

Answer 35

low pass channel

Question 36

also known as modulation, means changing the digital | signal to an analog signal for transmission

Answer 36

broadband transmission

Question 37

a channel with a bandwidth that does not | start from zero

Answer 37

bandpass channel

Question 38

CAUSES OF TRANSMISSION IMPAIRMENT

Answer 38

attenuation distortation noise

Question 39

- measures the relative strengths of two signals | or one signal at two different points

Answer 39

decibel

Question 40

- signal changes its form or shape - occurs in a composite signal made of different frequencies

Answer 40

distortation

Question 41

5 types of noises

Answer 41

thermal induced crosstalk impulse

Question 42

random motion of electrons in a wire which | creates an extra signal

Answer 42

thermal noise

Question 43

comes from the sources such as motors and | appliances

Answer 43

induced noise

Question 44

effect of one wire on the other

Answer 44

crosstalk

Question 45

spike that comes from power lines, lightning, etc

Answer 45

impulse

Question 46

- ratio of what is wanted (signal) to what is not wanted (noise)

Answer 46

signal-to-noise ration (SNR)

Question 47

3 data rate factors

Answer 47

bandwidth available levels of signals quality of channel

Question 48

calculating data rate

Answer 48

nyquist bit rate (noiseless channel) shannon capacity (noisy channel)

Question 49

refers to the range of frequencies in a composite signal or the range of frequencies that a channel can pass

Answer 49

bandwidth in hertz

Question 50

refers to the speed of bit transmission in a channel or link

Answer 50

bandwidth in bps

Question 51

measure of how fast we can actually send data | through a network

Answer 51

throughput

Question 52

defines how long it takes for an entire message to | completely arrive at the destination from the time the first bit is sent out from the source

Answer 52

latency (delay)

Question 53

measures the time required for a bit to travel from the source to the destination

Answer 53

propagation time propagation time = distance / propagation speed transmission time = message size / bandwidth