EST PART 1

Question 1

Collection of electronic components and circuits designed to convert the information into a signal. It’s functions are: Encoding Compression, Error correcting operations, and Modulatation processes.

Answer 1

-TRANSMITTER

Question 2

The reduction of signal amplitude as it passes over the transmission medium

Answer 2

-ATTENUATION

Question 3

Random, undesirable electric energy that enters the communication. It can be also defines as any unwanted introduction of energy tending to interfere.

Answer 3

-NOISE

Question 4

TYPES OF NOISE

Answer 4

1. External
2. Internal

Question 5

It is introduces in the medium/channel and difficult to quantify.

Answer 5

-EXTERNAL

Question 6

It is produced at the receiver resistor, diodes, transistor, wires.

Answer 6

-INTERNAL

Question 7

TYPES OF EXTERNAL NOISE

Answer 7

1. Industrial/man made noise
2. Atmospheric/static noise
3. Extraterrestrial/space noise

Question 8

Occurs randomly at a frequency up to 600 MHz.

Answer 8

-INDUSTRIAL/MAN MADE NOISE

Question 9

Caused by lightning discharges during the thunderstorms and other natural electrical disturbances occuring in earth’s atmosphere less severe above 30MHz.

Answer 9

-ATMOSPHERIC/STATIC NOISE

Question 10

Can be observe between 8MHz to 1.5GHz.

Answer 10

-EXTRATERRESTRIAL/SPACE NOISE

Question 11

TYPES OF INTERNAL NOISE

Answer 11

1. Thermal noise
2. Shot noise
3. Flicker noise

Question 12

Also called brownian noise. It is associated with the rapid and random movement of electrons within a conductor.

Answer 12

-THERMAL NOISE

Question 13

Is caused by the random arrival of carriers at the output element of an electronic device, such as diode, FET, OR BJT

Answer 13

-SHOT NOISE

Question 14

Noise found at low audio frequencies in transistors. Proportional to the emitter current and junction temperature. Inversely propotional to frequency.

Answer 14

-FLICKER NOISE

Question 15

Process of altering some of the characteristics of the carrier wave by impressing the modulating signal either by amplitude, frequency, or by phase information.

Answer 15

-MODULATION

Question 16

Is the process of recoversing the modulating signal back to modulated carrier.

Answer 16

-DEMODULATION

Question 17

Also known as the information signal. It can be a voice/audio, picture/audio, and data.

Answer 17

-MODULATING SIGNAL

Question 18

TYPES OF MODULATION

Answer 18

1. Amplitude Modulation (AM)
2. Angle Modulation
3. Frequency Modulation (FM)
4. Phase Modulation (PM)

Question 19

It is a modulation process where in the amplitude of the carrier is made proportional to the instantaneous amplitude of the intelligence.

Answer 19

-AMPLITUDE MODULATION

Question 20

It is a type of analog modulation where in the frequency or phase of the carrier is varied in accordance with the instantaneous amplitude of the modulating signal.

Answer 20

-ANGLE MODULATION

Question 21

It is an angle modulation where the instantaneous frequency of a carrier is caused to vary by an amount proportional to the modulating signal amplitude.

Answer 21

-FREQUENCY MODULATION

Question 22

Angle modulation where the phase angle of a carrier is caused to depart from its reference value by an amount proportional to the modulating signal amplitude.

Answer 22

-PHASE MODULATION

Question 23

It is the process of transferring digital information (usually in binary form) between two or more points. Information that has been processed, organized, and stored is called data.

Answer 23

-DATA COMMUNICATION

Question 24

It is a system of computers, computer terminals use to transmit and/or receive information between two or more locations.

Answer 24

-DATA COMMUNICATION NETWORK

Question 25

These are set of rules governing the orderly exchange of data within the network or a portion of the network.

Answer 25

-DATA COMMUNICATION PROTOCOLS

Question 26

It created the sets of rules and standards for graphics and document exchange and provide models for equipment and system compatibility, quality enhancement.

Answer 26

-INTERNATIONAL STANDARDS ORGANIZATION

Question 27

Is one of four permanent parts of the internation telecommunications union based in geneva, switzerland.

Answer 27

-COMITE CONSULTATIF INTERNATIONALE DETELEGRAPHIE AT TELEPHONIE

Question 28

Network and service operation, tariff and accounting principles.

Answer 28

-THE ITU-T

Question 29

It is the name for a set of standards for communicatingamong computers. It is also to serve as a structural guideline for exchanging information between computers.

Answer 29

-OPEN SYSTEMS INTERCONNECTION

Question 30

Adopted a seven layer communications architecture reference model. Each layer consists of specific protocols for communication.

Answer 30

-ISO AND ITU-T (CCITT)

Question 31

It is used to amplify signals carried by a network. It is used to lengthen individual network segments to form a large extended network.

Answer 31

-REPEATER

Question 32

Used to build a LAN by connecting different computers in a star/hierachal network topology.

Answer 32

-HUBS

Question 33

There are two types of hubs

Answer 33

1. Passive 2. Active

Question 34

The signal is forwarded as it is doesn't need power supply.

Answer 34

-PASSIVE

Question 35

The signal is amplified, so they work as repeaters. In fact thet have been called multiport repeaters. (uses power supply)

Answer 35

-ACTIVE

Question 36

Connected multiple devices on a network similar to a hub, but this have the ability to remember which device is connected. It reduces traffic and divide the collision domain intto segments.

Answer 36

-SWITCHES

Question 37

Use to extend networks by maintaining signals and traffic. It is on data link layer (ISO-OSI Model) they are capable to do data filtering and separatinh the collison domain, but they are less advanced. They are known to be used to extend distance capabilities of networks.

Answer 37

-BRIDGES

Question 38

Used to connect different LANs od a LAN with a WAN. It controls both collision domains and broadcast domains. It work on the network layer so they can filter data based on IP addresses.

Answer 38

-ROUTERS

Question 39

It is appropriate software to connect and translate data between networks with different protocols or architecture. It operates at the network layer and above.

Answer 39

-GATEWAYS

Question 40

TYPES OF AREA NETWORK

Answer 40

1. LAN 2. WLAN 3. WAN 4. MAN 5. SAN 6. CAN

Question 41

It is a computer network thet interconnects computers in a limited area such as a home. It is typically controlled and managed by a single person.

Answer 41

-LOCAL AREA NETWORK

Question 42

A LAN based on wifi wireless network technology

Answer 42

-WIRELESS LOCAL AREA NETWORK

Question 43

It is a network that covers a broad area any telecommunications network that links across metropolitan, regional, or national boundaries using a private or public network transports.

Answer 43

-WIDE AREA NETWORK

Question 44

It is a computer network that usually spans a city or a large campus. Usually interconnects a number of local area networks using a high capacity backbone technology.

Answer 44

-METROPOLITAN AREA NETWORK

Question 45

Sometimes called system area network. It connects servers to data storage devices through a technology like a fiber channel.

Answer 45

-STORAGE ARE NETWORK

Question 46

Sometimes called a cluster area network. A network spanning multiple LANs but smaller than a MAN, such as on a university or local business campus.

Answer 46

-CAMPUS AREA NETWORK

Question 47

It is transmission digital signals between the transmitter and receivers and requires physical transmission medium such as cable, fiber optic.

Answer 47

-DIGITAL TRANSMISSION

Question 48

It is transmission of digitally modulated signals between transmitter and receivers and requires free space (air) transmission medium.

Answer 48

-DIGITAL RADIO

Question 49

It is measure of how much information can be transmitted/propagated through a communication system. It also known as channel capacity.

Answer 49

-INFORMATION CAPACITY

Question 50

Ideal noiseless transmission medium at a rate or equal to two times the bandwidth of the medium. The minimum theorotical bandwidth to propagate a signal is called the minimum nyquist bandwidth.

Answer 50

-NYQUIST THEOREM

Question 51

Developed a useful relationship among bandwidth, transmission time and information capacity.

Answer 51

-HARTLEY'S LAW

Question 52

Theoretical expression of how many bits of information per second can be transmitted without error over a communication channel with a bandwidth.

Answer 52

-SHANNON-HARTLEY EQUATION

Question 53

It is the transmittal of digitally modulated analog signal (carrier) between two or more points in a communication system.

Answer 53

-DIGITAL MODULATION

Question 54

TYPES OF DIGITAL MODULATION

Answer 54

1. Amplitude Shift Keying 2. Frequency Shift Keying 3. Phase Shift Keying 4. Quadraturre Amplitude Modulation

Question 55

is the number of bits transmitted during 1 second.

Answer 55

-BIT RATE

Question 56

Is the number of signal units per second.

Answer 56

-BAUD RATE

Question 57

It is the simplest digital modulation techniques, where a binary information signal directly modulates the amplitude of analog carrier.

Answer 57

-AMPLITUDE SHIFT KEYING

Question 58

It is a form of constant-amplitude angle modulation similar to standard frequency modulation.

Answer 58

-FREQUENCY SHIFT KEYING

Question 59

It is another form of angle-modulated, constant amplitude digital modulation.

Answer 59

-PHASE SHIFT KEYING

Question 60

It is another form of angle-modulated, varying amplitude digital modulation. It is a combination of ASK and PSK so that a maximum contrast between each signal is achieved.

Answer 60

-QUADRATURE AMPLITUDE MODULATION

Question 61

The exchange of information through electrical/optical means between source and destination within a physically bounded medium.

Answer 61

-WIRE COMMUNICATION

Question 62

PHYICAL TRANSMISSION MEDIA

Answer 62

1. Metallic cable 2. Twisted pair 3. Coaxial cable 4. Optical fiber

Question 63

It is a metallic conductor system that is used to transfer electrical energy from one point to another. Used to propagete low frequency or high frequency signals.

Answer 63

-TRANSMISSION LINES

Question 64

GENERAL TYPES OF TRANSMISSION LINES

Answer 64

1. Balanced 2. Unbalanced

Question 65

Both conductors carry current for signal and return. The signal propagating down the wire is measured as the potential difference between two wires.

Answer 65

-BALANCED LINES

Question 66

One for signal and one for ground. Ground wire may also be the reference for other signal carrying wires.The gound must go wherever the signal go.

Answer 66

-UNBALANCED LINES

Question 67

A circuit device used to connect a unbalanced transmission line such as coax to an balanced load such as twin lead and antenna.

Answer 67

-BALUNS

Question 68

A two paralled conductor, closely spaced and separated by air. Non conductive spacers are placed at periodic intervals for support and to keep the distance between the conductors constant generally between 2-6 inches.

Answer 68

-OPEN WIRE TRANSMISSION LINE

Question 69

Often called ribbon cable (300ohms, impedance-balanced). Spacer between two conductors are solid dielectric.

Answer 69

-TWIN LEAD

Question 70

Formed by twisting together two insulated conductors. Pairs are often stranded in units, and units are often cabled into cores. Neighboring pairs are twisted with different pitch to reduce interference between pairs due to mutual induction.

Answer 70

-TWISTED PAIR CABLE

Question 71

Parallel conductor TL are suitable only for low frequency applications. It is for high frequency that reduces losses and isolate transmission paths. At high frequency, outer conductor provides excellent shielding against external interference.

Answer 71

-CONCENTRIC OR COAXIAL TRANSMISSION LINES

Question 72

It is a cable containing one or more optical fibers. It is typically individually coated with plastic layers and contained in a protective tube suitable for the environment.

Answer 72

-FIBER OPTIC CABLE

Question 73

Fibers are used for long distance transmission and required the use of laser as a light source, while multimode fibers can be use more types of light sources but cannot be used over long distances.

Answer 73

-SINGLE MODE

Question 74

The cable is wheree all the light is concentrated.

Answer 74

-THE CORE

Question 75

This is the layer of glass surrounding the core and it has the function of maintaining the light within the core itself. It provides a degree of mechanical strength and allows a more suitable size for handling purposes.

Answer 75

-THE CLADDING

Question 76

Only one path for light to take down the cable. Extremely wide bandwidths and low losses.

Answer 76

-SINGLE-MODE

Question 77

The light wave rays take many paths between the source and the far end of the fiber. Placed 2km between repeaters.

Answer 77

-MULTIMODE FIBER

Question 78

The core has a uniform index of refraction providing an abrupt change in refraction index at the core cladding interface.

Answer 78

-STEP INDEX

Question 79

The core has index of refaction that changes continuously from the center to the outside.

Answer 79

-GRADED INDEX

Question 80

A soft silicon resin applied over the cladding in order to preserve the internet strength of the glass fiber. Without this coating, the fiber would become brittle.

Answer 80

-THE PRIMARY COATING

Question 81

FIBER CONSTRUCTION

Answer 81

1. Glass fiber-optic cable 2. Plastic fiber-optic cable 3. Plastic-clad silica

Question 82

Gives off energy with a wavelength from about 300 microns down to 0.5 microns.

Answer 82

-LIGHT SOURCES

Question 83

Non-coherent injection light sources which are low-cost, low-heat, light sources and are the most promising light sources for optical transmission.

Answer 83

LIGHT EMITTING DIODE

Question 84

Make the most efficient use of electric energy. This coherent light source can couple a few milliwatts of light power into a fiber since it has a more direct radiation pattern.

Answer 84

-INJECTION LASER DIODES

Question 85

When photons are absorbed by intrinsic electrons in the valence band, they add sufficient energy to generate carriers in the depletion region.

Answer 85

-POSITIVE INTRINSIC NEGATIVE

Question 86

Light enters diode and is absorbed by the thin, heavily doped n-layer causing a high electric field intensity to e across in p-n juction.

Answer 86

-AVALANCHE PHOTO DIODE