SATELLITE MULTIPLE ACCESSING ARRANGEMENTS (c26)

CHAPTER 26
SATELLITE MULTIPLE ACCESSING ARRANGEMENTS

1)
Also called as Multiple Destination, It implies that more than one user has access to one or more radio channels within a satellite communications channel.
 Multiple Accessing

Multiple Accessing Arrangement:
 Frequency-division multiple accessing (FDMA)
 Time-division multiple accessing (TDMA)
 Code-division multiple accessing (CDMA)

2)A given number of the available voice-band channels from each earth station are assigned a dedicated destination.
Pre-assignment(dedicated)
 

3)Voice channels are assigned on an as-needed basis.
Demand Assignment
 

4)The method of assigning adjacent channels different electromagnetic polarizations and is possible by using orthogonal polarization and spacing adjacent channels 20 MHz apart.
Frequency Reuse
 

5)Eskimo word meaning “little brother”.
Anik
 

6)Domestic Satellites operated by Telsat Canada.
Anik-E communications Satellite
 

7)A method of multiple accessing where a given RF bandwidth is divided into smaller frequency bands.
FDMA
 

8)Multiple channel per carrier formats assigned and remain fixed for a long Period of time.
Fixed-Assignment, Multiple Access (FAMA)

9)Assigning carrier frequency on temporary basis using a statistical assignment process.
Demand-Assignment
Multiple Access
 

10)An acronym for Single-channel-per-carrier PCM multiple Access Demand-assignment Equipment.
SPADE
 

11)Stands for Single-Carrier-Per-Channel.
SCPC
 

12)A time division-multiplexed transmission that is frequency division multiplexed.
Common Signaling Channel (CSC)
 

13)The predominant Multiple-access method of time-division multiplexing digitally modulated carriers between participating earth stations within a satellite network through a common satellite transponder.
TDMA
 

14)An RF-to-RF repeater that simply receives the earth station transmissions, amplifies them, and then re-transmit them in a downlink beam that is received by all other participating station.
Transponder
 

15)It is where transmissions from all earth stations are synchronized.
Reference Burst
 

16)It is where all receiving stations recover a frequency and phase coherent carrier for PSK demodulation
Carrier Recovery Sequence (CRS)
 

17)An acronym for Conference of European Postal and Telecommunications Administrations, is commonly used TDMA frame format for digital satellite system
CEPT
 

18)Sometimes referred to as Spread-Spectrum Multipleentire allocated bandwidth Access, the transmissions can spread throughout the
Code-Division Multiple Access (CDMA)

19)A unique binary word that each earth station’s transmissions are encoded.
Chip Code
 

20)It compare two signals and recover the original data.
Correlator
 

21)It assigns an individual terrestrial channel (TC) to a particular satellite channel (SC) for the duration of the call.
Digital non interpolated Interface
 

22)It assigns a terrestrial channel to a satellite channel only when speech energy is present on the TC.
Digital Speech Interpolated Interface
 

23)A form of analog channel compression that has been used for sub oceanic cables for many years.
Time-Assignment Speech Interpolation (TASI)
 

24)The art or science of plotting, ascertaining or directing the course of movements, in other words, knowing where you are and being able to find your way around.
Navigation
 

25)It is the most ancient and rudimentary method of navigation and simply continuing to travel about until you reach your destination, assuming of course that you have one.
Wandering
 

26)Earliest effective means of navigation wherein direction and distance are determined from precisely timed sightings of celestial bodies, including the stars and moon.
Celestial Navigation
 

27)Method of navigation by means of fixing a position and direction with respect to familiar, significant landmarks such as railroad tracks, water towers, barns, mountains and bodies of water.

Piloting

28)A navigation technique that determines position by extrapolating a series of measured velocity increments.
Dead Reckoning
 

29)The term derived from the word “deduced” and not necessarily from the fate of the people who used the technique.
Dead
 

30)He used dead reckoning successfully in 1927 during his historic 33-hour transatlantic journey.
Charles Lindbergh
 

31)She attempted to make the first around-the-world in 1937 using the dead reckoning technique.
Amelia Earhart
 

32)Navigation technique wherein the position is deter-mined by measuring the travel time of an electro magnetic wave as it moves from a transmitter to a receiver.
Radio Navigation
 

33)A radio Navigation system for terrestrial surface broadcast.
Decca
 

34)Radio Navigation system that provide global coverage and terrestrial surface broadcast.
Omega
 

35)Also a terrestrial surface broadcast.
LORAN
 

36)Low-orbit satellite broadcast, provides global coverage.
Navy Transit GPS
 

37)Medium-orbit satellite broadcast also provides global coverage.
Navstar GPS
 

38)Means of radio navigation in which receivers acquire Coded signals from two pairs of high-powered, land based transmitters whose locations are precisely known.
LORAN
 

39)An acronym for Navigation System with Time and Ranging.
Navstar

40)An abbreviation for Global Positioning System.
GPS

Two levels of service or accuracy:
 Standard Positioning Service
 Precise Positioning Service

41)A satellite-based open navigation system which simply means that it is available to anyone equipped with a GPS receiver.
 Navstar GPS

Consists of three segments:
 a space segment
 a ground control segment
 user segment

42)It is when was the Navstar declared as fully operational by the U.S. Air Force Space Command.
April 27, 1995
 

43)It was completed in 1994 and is maintained by the United States Air Force.
Navstar Satellite System
 

44)A positioning and timing service that is available to all GPS users on a continuous, worldwide basis with no direct change.
Standard Positioning Service
 

45)Sometimes called Space Segment, consists of 24operational satellites revolving around Earth in six orbital planes approximately 60° apart with four satellites in each plane.
Satellite Segment
 

46)It produces highly accurate timing signals for satellites.
Cesium Atomic Clock
 

47)A unique integer number that is used to encrypt the signal from that satellite.
Pseudorandom Noise (PRN) Code Number
 

48) A term associated with a table showing the position of a heavenly body on a number dates in a regular sequence, in essence, an astronomical almanac.
Ephemeris

49)Error in the receiver’s clock which affects the accuracy of the time-difference measurement.
Clock Bias Error
 

50)The Navstar control segment.
It consists of :
 Fixed-location ground based monitor stations
 Master Control Station
 uplink transmitter
Operational Control System
 

51)It makes standard GPS more accurate. It works by canceling out most of the natural and man-made errors that creep into normal GPS measurements.
Differential GPS

SATELLITE COMMUNICATIONS (c25 Tomasi)

CHAPTER 25
SATELLITE COMMUNICATIONS

1)A celestial body that orbits around a planet.
Satellite

2)Man-made satellites that orbit earth, providing a multitude of communication functions to a wide variety of consumers, including military, governmental, private and commercial subscriber.
Communications Satellites

3)A satellite radio repeater which a satellite may have many.
Transponder

Consists of :
input Bandlimiting device (BPF)
input low-noise amplifier (LNA)
frequency translator
low level amplifier
output bandpass filter

4)It consists of one or more satellite space vehicles, a ground-based station to control the operation of the system, and a user network of earth stations that provides the interface facilities for the transmission and reception of terrestrial communications traffic through the satellite system.
Satellite System

5)It includes control mechanism that support the payload operation.
Bus

6)The actual user information conveyed through the system.
Payload

7)A type of satellite wherein it simply “bounces” signals from one place to another.
Passive Reflector

8)A natural satellite of Earth, visible by reflection of sunlight having a slightly elliptical orbit.
Moon

9)Used by passive satellites for tracking and ranging purposes.
Radio Beacon Transmitters

10)Launched by Russia, the first active earth satellite in 1957. It transmitted telemetry for 21 days.
Sputnik I

11)A type of satellite capable of receiving, amplifying, reshaping, regenerating and retransmitting information.
Active Satellite

12)Satellite launched by U.S., it transmitted telemetry information for nearly five months.
Explorer I

13)Satellite launched by NASA in 1958, a 150-pound conical-shaped satellite. It was the first artificial satellite used for relaying terrestrial communications.
Score

14)The first active satellite to simultaneously receive and transmit radio signals.
Telstar I

15)Launched in 1963, and was used for telephone television, facsimile and data transmission and accomplished the first successful transatlantic video transmission.
Telstar II

16)Launched in February 1963, was the first attempt to place a geosynchronous satellite into orbit.
Syncom I

17)It was the first commercial telecommunications satellite. It launched from Cape Kennedy in 1965 and used two transponders. Also called as Early Birds.It stands for International Telecommunications Sate-llite.
Intelsat I

18)Domestic satellite launched by former Soviet Union in 1966. It means “lighting”.
Molya

19)A German astronomer who discovered the laws thatgoverns satellite motion.
Johannes Kepler

20)It may be simply stated as: 

The planets move in ellipses with the sun at one focus 

The line joining the sun and the planet sweeps out equal intervals of time.
The square of the time of revolution of a planet divided by the cube of its mean distance from the sun gives a number that is the same for all planets.
Kepler’s Law

21)The point in an orbit closest to earth
Perigee

22)The point in an orbit farthest from the earth.
Apogee

23)It states that the square of the periodic time of orbit is proportional to the cube of the mean distance between the primary and the satellite.
Harmonic Law

24)High-altitude earth-orbit satellites operating primarily in the 2-GHz to 18 GHz frequency spectrum with orbits Satellite 22,300 miles above earth’s surface.
Geosynchronous Satellite

Advantages of Geosynchronous Satellite:
It remain almost stationary in respect to a given earth station.
Available to earth within their shadows 100% of the time.
No need to switch from one geosynchronous satellite to another as they orbit overhead
The effects of Doppler shift are negligible

Disadvantages of geosynchronous Satellite:
It requires sophisticated and heavy propulsion device onboard to keep them in a fixed orbit
Much longer propagation delays

Requires higher transmit power and more sensitive receivers because of the longer distances and greater path loss.
High precision spacemanship is required.

25)The angle between the earth’s equatorial plane and the orbital plane of a satellite measured counter clockwise at the point in the orbit where it crosses the equatorial plane traveling from south to north called the ascending node.
Angle of Inclination

26)The point where the polar or inclines orbit crosses the equatorial plane travelling from north to south
Descending Node

27)The line joining the ascending and descending node
Line of Nodes

28)It is when the satellite rotates in an orbit directl above the equator, usually in a circular path.
Equatorial Orbit

29)It is when the satellite rotates in path that takes over the North and the South poles in an orbit that is close to earth and passes over and very close to both the North and South Poles.
Polar Orbit

30)The noise power normalized to a 1 Hz bandwidth, or the noise power present in a 1Hz bandwidth
Noise Density

31)It identifies the system parameters and is used to determine the projected carrier-to-noise ratio and energy Bit-to-noise density ratio at both the satellite and earth station receivers for a given modulation scheme.
Link Budget

MICROWAVE RADIO COMMUNICATIONS AND SYSTEM GAIN (c22 Tomasi)

CHAPTER 24
MICROWAVE RADIO COMMUNICATIONS AND SYSTEM GAIN

1)Electromagnetic waves with frequencies that range from approximately 500 MHz to 300 GHz or more.
Microwaves

2)The wavelengths for microwave frequencies, which is than infrared energy.
1 cm and 60 cm slightly longer

3)The name given to microwave signals, because of their inherently high frequencies, have short wavelengths.
“Microwave” waves

4)Each frequency is divided in half with the lower half identified as the low band and the upper half as narrow band.
Full-Duplex (Two-way)

5)Communications system used to carry information for relatively short distances such as between cities with the same state.
Short Haul

6)Microwave systems that is used to carry information for relatively long distances, such as interstate and backbone route applications.
Long Haul

7)It propagate signals through Earth’s atmosphere between transmitters and receivers often located on top of tower spaced about 15 miles to 30 miles apart.

Microwave Radios 

Advantages of Microwave Radio:
 Radio systems do not require a right-of way acquisition between stations.
 Each station requires the purchase or lease ofonly a small area of land.
 Because of their high operating frequencies, microwave radio systems can carry large quantities of information.
 High frequencies mean short wavelengths, which require relatively small antennas.
 Radio signals are more easily propagated around physical obstacles such as water and high mountains
 Fewer repeaters are necessary for amplification.
 Distances between switching centers are less.
 Underground facilities are minimized.
 Minimum delays are introduced.
 Minimal crosstalk exists between voice channels.
 Increased reliability and less maintenance are important factors.
Disadvantages of Microwave Radio:
 It is more difficult to analyze and design circuits at microwave frequencies.
 Measuring techniques are more difficult to perfect and implement at microwave frequencies.
 It is difficult to implement conventional circuit components at microwave frequencies.
 Transient time is more critical at microwave frequencies.
 It is often necessary to use specialized components for microwave frequencies.
 Microwave frequencies propagate in a straight line, which limits their use to line-of-sight applications.

8)Propagates signals outside the Earth’s atmosphere and are capable of carrying signals much farther while utilizing fewer transmitters and receivers.
Satellite Systems

9)It is used in microwave radio systems rather than amplitude modulation because AM signals are more sensitive to amplitude nonlinearities inherent in wide-band microwave amplifiers.
Frequency Modulation

10)Major factor when designing FM Radio systems. It is caused by repeater amplitude nonlinearity in AM, while in FM, it is caused by transmission gain and delay distortion.
Intermodulation Noise

11)The composite signal that modulates the FM carrier and may comprise one or more of the following:
 Frequency-division multiplexed voice-band channels
 Time-division-multiplexed voice-band channels
 Broadcast-quality composite video or picture phone
 Wideband data
Baseband

12)It provides an artificial boost in amplitude to the higher baseband frequencies.
Preemphasis Network

13)Frequency modulation index used in the FM deviator. Typically, modulation indices are kept between 0.5 and 1.
Low-Index 

14)FM signal that is produces at the output of the deviator with a low-index frequency modulation.
Narrowband FM

15)A receiver and a transmitter placed back to back or in tandem with the system.
Microwave Repeaters

16)It receives a signal, amplifies and reshapes it, and then retransmit the signal to the next repeater or terminal station down line from it.

Repeater Station
Types of Microwave repeaters:
 IF
 Baseband
 RF

17)The received RF carrier is down-converted to an IF frequency, amplified, reshaped, up-converted to an RF frequency, and then retransmitted.
IF Repeater

18)Generally less than 9 MHz.
Baseband Frequencies

19)The range id 60 MHz to 80MHz.
IF frequencies

20)Another name for a Local oscillator, is considerably lower in frequency than either the received or the transmitted radio frequencies.
Shift Oscillator

21)Transmission used by microwave systems wherein a direct signal path must exist between the transmit receive antennas.
Line-of Site Transmission

22)A temporary reduction in signal strength which last in milliseconds for several hours or even days.
Radio Fade

23)It suggests that there is more than one transmission path or method of transmission available a transmitter and a receiver.
Diversity

24)It is simply modulating two different RF carrier frequencies with the same IF intelligence, then transmitting both RF signals to a given destination.
Frequency Diversity

25)The output of a transmitter is fed to two or more antennas that are physically separated by an appreciable number of wavelengths.
Space Diversity

26)A single RF carrier is propagated with two different electromagnetic polarizations. It is generally used in conjunction with space diversity.
Polarization Diversity

27)It is more than one receiver for a single radio-frequency channel. With frequency diversity, it is necessary to also use receiver diversity because each transmitted frequency requires its own receiver
Receiver Diversity

28)Another form of Hybrid diversity and undoubtly provides the most reliable transmission but most expensive. It combines frequency, space, polarization and receiver diversity into one system.
Quad Diversity

29)A specialized form of diversity that consist of a standard frequency diversity path where the two transmitter/ receiver pairs at one end of the path are separated from each other and connected to different antennas that are vertically separated as in space diversity.
Hybrid Diversity

29)Alternate facilities temporarily made to avoid a service interruption during periods of deep fades or equipment failures.
Protection Switching Arrangement

types of protection switching arrangements:
 hotstandby
 diversity

30)Each working radio channel has a dedicated backup or spare channel.
Hot Standby Protection

31)A single backup channel is made available to as many as 11 working channels.
Diversity Protection

32)In hotstandby protection, it splits the signal power and directs it to the working and the spare (standby)microwave channels simultaneously.
Head-End Bridge

33)It has two working channels, one spare channel, and an auxiliary channel.
Diversity Protection

34)A low-capacity low-power microwave radio that is designed to be used for a maintenance channel only.
Auxilliary Channel

35)It is where the number of repeater stations between protection switches depends.
Reliability Objectives of the Systems

36)Points in the system where baseband signals either originate or terminate.
 Terminal Stations

four major sections:

 baseband
 wireline entrance link (WLEL)
 FM-IF
 RF sections

37)Points in a system where baseband signals may be reconfigured or where RF carriers are simply “repeated” or amplified.
Repeater Stations

38)Stands for WireLine Entrance Link, it serves as the interface between the multiplex terminal equipment and the FM_IF equipment.
WLEL

39)A balanced modulator that, when used in conjunction with a microwave generator, power amplifier, and band-pass filter, up-converts the IF carrier to an RF carrier and amplifies the RF to the desired output power.
Transmod

40)It must be capable of amplifying very high frequencies and passing very wide bandwidth signals for microwave radios.
Power Amplifiers

devices used in microwave amplifiers:
 Klystron Tubes
 Traveling-wave tubes (TWTs)
 IMPATT (Impact avalanche and transit time)

41)It provides the RF carrier input to the up-converter. It is called as microwave generator rather than an oscillator because it is difficult to construct a stable circuit that will oscillate in the gigahertz range.
Microwave Generator

42)It operates in the range 5 MHz to 25 MHz, used to provide a base frequency that is multiplied up to the desired RF carrier frequency.
Crystal-controlled Oscillator

43)A unidirectional device often made from ferrite material. It used in conjunction with a channel-combining network to prevent the output of one transmitter from interfering with the output of another transmitter.
Isolator

44)Stands for Automatic Gain Control, is a circuit in an IF amplifier.
AGC

45)It occurs only when three stations are placed in a geographical straight line in the system.
Multi-hop Interference

46)It prevents the power that “leaks” out the back and sides of a transmit antenna from interfering with the signal entering the input of a nearby receive antenna.
High/Low-Frequency Scheme

47)The signal entering the input of a nearby receive antenna.
Ring around

48)It means that this channels are propagated with vertical polarization.
V Channels

49)The line-of-sight directly between the transmit and receive antenna. Also called as the Direct Wave.
Free-Space Path

50)It consists of the electric and magnetic fields associated with the currents induced in earth’s surface.
Surface Wave

51)The portion of the transmit signal that is reflected off Earth’s surface and captured by the receive antenna.
Ground-Reflected Wave

52)The portion of the transmit signal that is returned back to Earth’s surface by the ionized layers of earth’s atmosphere.
Sky Wave

53)The loss incurred by an electromagnetic wave as it propagates in a straight line through a vacuum with no absorption or reflection of energy from nearby objects.
Free-Space Path Loss

54)A phenomenon wherein electromagnetic energy is spread out as it propagates away from the source resulting in lower relative power densities.
Spreading Loss

55)The reduction in signal strength at the input to a receiver.
Fading

56)The difference between the nominal output power of a transmitter and the minimum input power to a receiver necessary to achieve satisfactory performance.
System Gain

57)Sometimes called as Link Margin, is essentially a “fudge Factor” included in system gain equations that considers the non ideal and less predictable characteristics of radio wave propagation and terrain sensitivity.
Fade Margin

58)He described ways of calculating outage time due to fading on a non diversity path as a function of terrain, climate, path length, and fade margin, in April 1969.
W.T. Barnett
59)From Bell Laboratories, he derived formulas for calculating the effective improvement achievable by vertical space diversity as a function of the spacing distance, path length, and frequency in June 1970.
Arvids Vignant

60)The ratio of the wideband “carrier” to the wideband noise power.
Carrier-to-Noise Ratio (C/N)

61)Also called Receiver Sensitivity, is the minimum wide band carrier power at the input to a receiver that will
provide a usable baseband output.
Receiver Threshold

62)The carrier-to-noise ratio before the FM demodulator.
Pre-detection Signal to-Noise Ratio

63)The carrier-to-noise ratio after the FM demodulator.
Postdetection Signal-to-Noise Ratio

64)A ratio of input signal-to-noise ratio to output signal to noise ratio.
Noise Factor (F)

65)The noise factor stated in dB and is a parameter commonly used to indicate the quality of a receiver.
Noise Figure

DATA-LINK PROTOCOLS AND DATA COMMUNICATIONS NETWORKS (c23 Tomasi)

CHAPTER 23

DATA-LINK PROTOCOLS AND DATA COMMUNICATIONS NETWORKS

1)The primary goal of __________ is to give users of a network the tools necessary for setting up the network and performing data flow control.

Network Architecture

2)A set of rules implementing and governing an orderly exchange of data between two layer devices.

Data-Link Protocol

3)The transmitting station in a data link protocol.

Master Station

4)The receiving station in a data link protocol.

Slave Station

5)Data link network wherein all stations have equal access to the network.

Peer-to Peer Network

6)Discipline, Flow Control and Error Control.

Functions of Data-link Protocol

7)Coordinates hop-to-hop data delivery where a hop may be a computer, a network controller, or some type of network-connecting device

Line Discipline

8)Determines which device is transmitting and which is receiving at any point in time.

Line Discipline

9)Coordinates the rate which data are transported over a link and generally provides an acknowledgement mechanism.

Flow Control

10)Specifies means of detecting and correcting transmission errors.

Error Control

11)Two fundamental ways that line discipline is accomplished in a data communications network.

Enquiry/Acknowledgement(ENQ/ACK) and Poll/Select

12)It determines which device on the network can initiate a transmission and whether the intended receiver is available and ready to receive a message.

ENQ/ACK

13)The initiating station begins a session by transmitting a frame, block, or packet of data called _________, which identifies the receiving station.

Enquiry(ENQ)

14)The response of the destination station when it is ready to receive.

Positive Acknowledgement (ACK)

15)The response of the destination station when it is not ready to receive.

Negative Acknowledgement (NAK)

16)The best application of the poll/select line discipline.

Centrally Controlled Data Network

17)A solicitation sent from the primary to a secondary to determine if the

secondary has data to transmit

Poll

21)A set of procedures that tells the transmitting station how much data it can send before it must stop transmitting and wait for an acknowledgment from the destination station

Flow Control

22)The transmitting station sends one message frame and then waits for an acknowledgement before sending the next message frame.

Stop-and Wait Flow Control

23)A source station can transmit several frames in succession before receiving an acknowledgement.

Sliding Window Flow Control

24)It refers to imaginary receptacles at the source and destination stations with the capacity of holding several frames of data.

Sliding Window

25)Primary advantage of sliding window control.

Network Utilization

26)Primary disadvantages of sliding window flow control.

Complexity and Hardware Capacity

27)Interpret a frame of data as a group of successive bits combined into predefined patterns of fixed length, usually eight bits each.

Character Oriented Protocols

28)Another name for character oriented protocols.

Byte-oriented Protocols

29)A discipline for serial by bit information transfer over a data communications channel.

Bit Oriented Protocol

30)A character-oriented protocols generally used on two point networks using asynchronous data and asynchronous modems.

Asynchronous Data link Protocols

31)Developed the first file transfer protocol designed to facilitate transferring data between two personal computers in 1979.

Ward Christiansen

32)Cristiansen's protocol which is relatively simple data link protocol intended for low-speed applications.

XMODEM

33)Remote stations can have more than one PC or printer.

Synchronous Data-Link Protocols

34)A group of computers, printers, and other digital devices.

Cluster

35)A synchronous character-oriented data link protocol developed by IBM.

Binary Synchronous Communications (BSC)

36)Another name for BSC.

Bisync

37)Another name for enquiry (ENQ) character.

Format or line turn around

38)The __________ uses longitudinal redundancy checking (LRC) with ASCII-coded messages and cyclic redundancy checking.

Block Check Character (BCC)

39)A synchronous bit oriented protocol developed in the 1970's by IBM for use in system network architecture environment.

Synchronous Data-Link Control (SDLC)

40)Three transmission states.

Transient, Idle and Active

41)Flag Fields, Address Field, Control Field, Information and Frame Check Sequence Field are __________.

SDLC Frame Fields

42)It is used for the delimiting sequence for the frame and to achieve frame and character synchronization.

Flags

43)It is used for polling, confirming previously received frames, and several other data link management functions

Control Field

44)Three frame formats with SDLC.

Information, Supervisory and Unnumbered

45)A command or a response that is used to send unnumbered information.

Unnumbered Information (UI)

46)A command that places a secondary station into the initialization mode.

Set Initialization Mode

47)A response sent by a secondary station to request the primary to send a SIM command.

Request Initialization Mode (RIM)

48)A command that places a secondary into the normal response mode.

Set Normal Response Mode (SNRM)

49)A response transmitted from a secondary station if the primary attempts to send numbered information frames to it when the secondary is in the normal disconnect mode.

Disconnect Mode (DM)

50)A response sent by a secondary when it wants the primary to place it in the disconnect mode.

Request Disconnect (RD)

52)An affirmative response that indicates compliance to SIM, SNRM or DISC commands

Unnumbered Acknowledgement

53)An exchange of frames between the primary station and a secondary station.

TEST

54)A flag followed by eight consecutive logic 0's.

Turnaround Sequence

55)A SDLC subcommand causes all previously set functions to be cleared by the secondary.

Clear

56)A SLDC subcommand causes the secondary receiving it to turn on or turn off its carrier.

Beacon Test

57)A SDLC command causes the addressed secondary station to pace itself into the monitor mode.

Monitor Mode

58)A SDLC command causes a secondary station to loop its transmission directly to its receiver input.

Wrap

59)A SDLC command causes the addressed secondary to initiate a series of internal diagnostic tests.

Self-Test

60)The transparency mechanism used with SDLC.

Zero Bit Insertion or Zero Stuffing

61)It is used prematurely terminate an SDLC frame.

Message Abort

62)The encoding scheme used in SDLC.

Invert-On-Zero Coding

63)Standard that defines the frame structure, delimiting sequence, transparency mechanism and error detection method used with HDLC.

ISO 3309

64)Operational Mode of SDLC.

Normal Response Mode (NRM)

65)A mode of operation logically equivalent to a two point private line circuit where each station has equal data link responsibilities.

Asynchronous Balanced Mode

66)A switched data communications network similar to the public telephone network except a PDN is designed for transferring data only.

Public Switched Data Network (PDN)

67)It is used when making a standard telephone call on the public telephone network.

Circuit Switching

68)Is a form of store and forward network.

Message Switching

69)Another name for packet switching.

Hold and Forward Network

70)A user interface as the international standard for packet network access.

X.25

71)SA logically equivalent to a two point dedicated private line circuit except slower.

Permanent Virtual Circuit (PVC)

72)A logically equivalent to making a telephone call through the DDD network except no direct end to end connection is made.

Virtual Call

73)Identifies whether the packet is a new call request or a previously established call.

Format Identifier

74)A 12 bit binary number that identifies the source and destination users for a given virtual call.

Logical Channel Identifier

75)This four bit gives the number of digits that appear in the calling address filed.

Calling Address Field

76)This field is the same as the calling address field except that it identifies the number of digits that appear in the called address field

Called Address Length

77)This field contains the destination address.

Called Address

78)This field is the same as the called address field except that it contains up to 15 BCD.

Calling Address

79)This field identifies the number of eight bit octets present in the facilities field.

Facilities Length Field

80)This 32 bit field is reserved for the subscriber to insert user level protocol.

Protocol Identifier

81)A proposed network designed by the major telephone companies in conjunction with the ITU-T.

Integrated Services Digital Network (ISDN)

82)Customers gain access to the ISDN system through a local interface connected to a digital transmission medium.

Digital Pipe

83)ISDN objectives that ensure universal access to the network.

System Standardization

84)Said objectives that allow customers to use a variety of protocols and applications

Achieving Transparency

85)ISDN should not provide services that preclude competitiveness

Separating Functions

86)Provide private-line and switched services refers what objectives of ISDN.

Variety of Configurations

87)ISDN services should not be directly related to cost and independent of the nature of the data.

Addressing Cost-Related Tariffs

88)Provide a smooth transition while evolving.

Migration

89)Provide service to low capacity personal subscribers as well as to large companies.

Multiplexed Support

90)Translation between non-ISDN data protocol and ISDN is performed in this device.

Terminal Adapter

91)A boundary to the network and may be controlled by the ISDN provider.

Network Termination 1

92)Refers to interfaces between the common carrier subscriber loop and the central office switch

U-Reference Point

93)The media interface point between an NT1 and the central office.

U Loop

94)It is defined by ITU-T as a service that provides transmission channels capable of supporting transmission rates greater than the primary data rate.

Broadband ISDN

95)Information transfer is primarily from service provider to subscriber

Distribution Services

96)Codes the data information into smaller packets used by the BISDN network

Broadband Node

97)A connection between a source and a destination, which may entail several ATM links.

Virtual Channel

98)Once data have entered the ATM network, they transferred into fixed time slots called ________.

Cells

99)Controls the flow of traffic across the user network interface (UNI) and into the network.

Generic Flow Control Field (GFC)

100)The first three bits of the second half of byte 4 specify the type of message in cell.

Payload Type Identifier

101)Information fields that are designed to accommodate PCM-TDM traffic, which allows the ATM network to emulate voice or DSN services.

Constant Bit Rate

102)A portion of a public service provider's switching system where the service provider could be a local telephone company or a long-distance carrier.

Public ATM Switches

103)Provides the most effective and economical means of handling local data communications field.

Local Area Networks (LAN)

104)A communications system that allows users to send messages to each other through their computers.

E-Mails

105)LAN Topologies.

Star, Bus and Ring Topology

106)It describes how users access the communications channel in a LAN.

Network Access Methodologies

107)Access method used primarily in bus topology.

CDMA/CD

108)It two stations transmit at the same time, ________ occurs.

Collision

109)The time it takes a signal to travel from a source to a destination.

Propagation Delay

110)A base band transmission system designed in 1972 by Robert Metcalfe and David Boggs.

Ethernet

111)Its purpose is to establish clock synchronization.

Preamble

112)It is simply a series of two logic 1's appended to the end of the preamble.

Start Frame Delimiter

113)Consists of six bytes the corresponds to the address of the station sending the frame.

Source Address