Data and Digital Communication Mocktest (Midterm) BSIT - 505

80問 • 4ヶ月前

問題一覧

In a _____________, data can flow in both directions, but never simultaneously. It first flows in one direction, and then in the other direction.

half-duplex transmission (HDX)

In a ___________, data can only flow in one direction, which is usually from the source to the sink.

simplex transmission

In a _______________, data can flow in both directions simultaneously. It can be viewed as a pair of simplex lines between the source and sink with one line going from the source to the sink and the other going from the sink to the source.

full-duplex transmission (FDX)

when data is sent or received, the data bits are organized in a specific order since they can only be sent one after another.

Serial data transmission

is used when data is transmitted as individual characters. In this method, each character is preceded by one start bit and one or two stop bits that are used by the receiver for synchronization purposes.

Asynchronous transmission

is used to transmit large blocks of data at a time. In this scheme, data is usually organized in frames and each frame is preceded by a flag that consists of a few bits and terminated by another flag

Synchronous transmission

multiple data bits are transmitted over multiple channels at the same time.

Parallel data transmission

It is a communication channel that carries the information from the sender to the receiver in which data is transmitted through the electromagnetic signals via copper wire, fiber optics, atmosphere, water, and vacuum. The function of these transmission media is to carry the information in the form of bits through the network.

Transmission Media

enables the transfer of information between two or more points that are connected by an electrical conductor.

Guided Media

it consists of two insulated copper wires that are typically about 1mm thick and twisted together in a helical form.

Twisted Pair

to facilitate two-way communication, the cable bandwidth is split into two sets of channels: upstream channels and downstream channels.

Coaxial Cable

refers to the medium and the technology associated with the transmission of information as light pulses along a glass or plastic wire or fiber the optical cable.

Optical Fiber

do not require physical links between two or more devices. Wireless communication is based on radio waves communications in the frequency spectrum.

Unguided media

These are easy to generate and can penetrate through buildings. The sending and receiving antennas need not be aligned. Example: AM and FM radios and cordless phones.

Radio waves

It is a line of sight (LOS) transmission i.e. the sending and receiving antennas need to be properly aligned with each other. The distance covered by the signal is directly proportional to the height of the antenna. These are majorly used for mobile phone communication and television distribution.

Microwaves

These waves are used for very short distance communication. They cannot penetrate through obstacles. This prevents interference between systems. It is used in TV remotes, wireless mouse, keyboard, printer, etc.

Infrared

It is the metal rod or dish that catches radio waves and turns them into electrical signals feeding into something like a radio or television or a telephone system.

Antennas

It is a directional antenna that is made of a series of dipoles placed along its axis at different space intervals of time followed by a logarithmic function of frequency.

Log Periodic Antennas

These antennas use a length of wire for transmitting and receiving wavelengths of signals.

Wire Antennas

It is a directional aperiodic antenna that uses a travelling wave as its guiding structure.

Traveling Wave Antennas

This type of antenna uses microwave transmission to broadcast signals between two or more locations.

Microwave Antennas

It is the range of frequencies contained by a signal.

Frequency Spectrum

Frequency: 3 KHz to 30 KHz Wavelength: 100 km to 10 km

ELF

Frequency: 30 KHz to 300 KHz Wavelength: 10 km to 1 km

Frequency: 300 KHz to 3000 KHz Wavelength: 100 km to 10 km

Frequency: 3 MHz to 30 MHz Wavelength: 100 m to 1 m

Frequency: 30 MHz to 300 MHz Wavelength: 10 m to 1 m

VHF

Frequency: 300 MHz to 3000 MHz Wavelength: 1 m to 100 mm

UHF

Frequency: 3 GHz to 30 GHz Wavelength: 100 mm to 10 mm

SHF

Frequency: 30 GHz to 300 GHz Wavelength: 10 mm to 1 mm

EHF

These waves are basically defined as superimposed oscillations of an electric and a magnetic field in space with their direction of propagation perpendicular to both. These are the following propagation that is currently used today

Wave Propagation

This is used for a low-frequency range transmission, mostly less than 1 MHz. This type of propagation employs the use of large antennas order of which is equivalent to the wavelength of the waves and uses the ground or Troposphere for its propagation.

Ground Wave

This is used for the propagation of EM waves with a frequency range of 3-30 Mhz. These waves makes the use of ionosphere in which it is the ionized part of the earth’s upper atmosphere.

Sky Wave

This is used for a line of Sight communication (LoS). Space satellite communication and very high-frequency waves use this propagation method.

Space Wave

It is a way of sending multiple signals or streams of information over a communications link at the same time in the form of a single, complex signal.

Multiplexing

The receiver recovers the separate signals, a process called _________.

demultiplexing

The utilization of such media can be increased by allowing multiple users to transmit their data simultaneously, or close to simultaneously.

Media Sharing Technique

In Media sharing techniques, it is where the frequency spectrum of the medium is partitioned into multiple frequency blocks called channels that are assigned to users who can use these channels simultaneously without interference from each other.

Frequency-division multiplexing (FDM)

In media sharing techniques, it is where transmission time is divided into non-overlapping time slots that are assigned to users. Transmissions are staggered using a round-robin method to schedule the transmissions.

Time-division multiplexing (TDM)

In media sharing techniques, it is where the output signal, which appears like noise, occupies more bandwidth than the original signal.

Spread spectrum (SS)

In CSMA/CD, it means that each station on the LAN continually listens to (tests) the cable for the presence of a signal before transmitting.

Carrier Sense

In CSMA/CD, it means that many computers are attempting to transmit and compete for the opportunity to send data (i.e., they are in contention).

Multiple Access

In CSMA/CD, it means that when a collision is detected, the stations will stop transmitting and wait a random length of time before retransmitting the data.

Collision Detection

Instead of detecting and reacting to collisions, ________ tries to avoid them by having each computer signal its intention to transmit before transmitting.

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)

It is a media access method by which collisions are prevented. Collisions are eliminated under this because only a computer that possesses a free token (a small data frame) can transmit. This method also allows different priorities to be assigned to different stations on the ring.

Token passing

In this, an active hub is an essential requirement that can control access to the network. The terminals on a network are required to obtain permission from the hub before they start transmitting the bytes over a network.

Demand priority

is an architecture used to interconnect two (2) devices together. It includes the design of the plug and socket, the type, and the number and purpose of the wires and the electrical signals that are passed across them.

hardware interface

it is the whole content of an entity of an interface standard.

Composition

deals with voltages, line capacitance, and other electrical issues.

Electrical component

deals with items such as the connector or plugs description.

Mechanical component

deals with the function of each pin used in an interface.

Functional component

describes how the circuits are used to perform an operation.

Procedural component

It is a digital interface that uses a standardized connector(plug) for all serial and parallel type devices which provides a digital interface and known for being hot-pluggable.

Universal Serial Bus (USB)

In USB, it is also known as hot swapping and is the ability to add and remove devices to a computer system while the computer is running and have the operating system automatically recognize the change.

Hot Plugging

It is a type of interconnection between peripheral devices (such as wireless modems and high-speed digital video cameras) and a microcomputer. This digital interface that is capable of supporting transfer speeds of up to 3.2 Gbps.

Fire Wire

It is currently found on Apple laptops and provides a 10-Gbps connection to peripheral devices. It uses the same connector as the already existing Mini DisplayPort and uses an already existing protocol called PO Express.

Thunderbolt

It is an 8-pin connector in which it can be found as the primary connector on the newer versions of Apple's iPhone as well as Apple devices such as the iPad.

Lightning

is a technique forninterfacing a computer to high-speed devices such as hard disk drives, tape drives, CDs, and DVDs. This was designed to support devices of a more permanent nature such as high-performance workstations and network servers.

SCSI

This interface is used due to its high-speed connection that is mostly found in networks that require large amounts of peripheral storage. It can carry multiplebchannels of data at the same time up to 2.5 billion bits (2.5 gigabits) per second (single data rate), 5 gigabits per second (double data rate), and 10 gigabits per second (quaddata rate); and it can address (interconnect) thousands of devices using both copper wire and fiber-optic cables.

InfiniBand

It is like InfiniBand in that it too is a serial, high-speed network that connects a computer to multiple input/output devices. It also supports data transfer rates up to billions of bits per second, but it can support the interconnection of up to 126 devices only.

Fibre Channel

a single character, or byte of data, is the unit of transfer between the sender and receiver. The sender prepares a data character for transmission, transmits that character with irregular timing, and then begins preparing the next data character for transmission.

Asynchronous connection

the unit of transmission is a sequence of characters. This sequence of characters may be thousands of characters in size with regular timing sent.

Synchronous connection

a special kind of data link connection used to support various types of real-timebapplications such as streaming voice, video, and music.

Isochronous connection

refers to the data-carrying capacity of a channel or medium. Higher bandwidth communication channels support higher data rates.

Bandwidth

refers to the leakage of signal from the medium due to undesirable electrical characteristics of the medium.

Radiation

refers to the susceptibility of the media to external electrical noise that can cause distortion of the data signal.

Noise Absorption

refers to the loss of energy as signal propagates outwards. The amount of energy lost depends on frequency. Radiations and physical characteristics of media contribute to this.

Attenuation

Bandwidth in ______ is the range of frequencies contained in a composite signal or the range of frequencies a channel can pass.

hertz

is the amount of data that enters and goes through a system. In layman’s term, it is a measure of how fast we can actually send data through a network.

Throughput

It is a measure of delay. It measures the time it takes for data to get to its destination across the network.

Latency

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

Propagation time

measures the time how long a message will pass in channel corresponding with the bandwidth.

Transmission time

measures the time needed for each intermediate or end device to hold the message before it can be processed.

Queuing time

measures how data is processed through or from links.

Processing delay

refers to the number of signal elements or symbol changes that occur per second. A symbol is one of several voltage, frequency, or phase changes.

Baud Rate

is the amount of data (number of bits) that can be transmitted per second. It is closer to bandwidth, but it is often per host or source to destination devices.

Bit Rate

In a _________, data is transferred from source to destination through a series of intermediate switching nodes. Data passes through a subset of the network nodes.

switched network

involves establishing a path from source to destination before the commencement of communication. The path is dedicated to the source-destination pair for the duration of the communication session.

Circuit switching

involves organizing data in blocks called packets that are sent in a store-and-forward manner without prior establishment of the communication path. By store-and-forward, we mean that when a node receives a packet, it stores the packet and checks it for errors.

Packet switching

In a _________, a transmission from a source is received by all nodes in the network. It ensures that all the nodes in the network see the transmitted data.

broadcast network

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