RC Exam - EST 11 TO EST 20
______ medium transport electromagnetic waves without using a physical conductor. Unwired Direct Unguided Guided
Unguided
In a ____ line coding scheme, all the signal levels are on one side of the time axis, either above or below. Bipolar Non-polar Unipolar Polar
Unipolar
In antenna arrays, a _____ array designates an array in which the direction of maximum radiation is perpendicular to the plane containing these elements. broadside wide narrow beam perpendicular
broadside
A ____ is a set of memory locations that can hold packets at the sender and receiver. compander inverter buffer compressor
buffer
As the wave enters into the upper part of the layer of ______ ionization, the velocity of the upper part of the wave decreases, and the wave is bent away from the Earth. decreasing increasing similar None of the choices
decreasing
The _____ uses a series of filters to decompose the multiplexed signal into its constituent component signals. multiplexer decoder demultiplexer encoder
demultiplexer
An ____ array is one in which the principal direction of radiation is along the plane of the array and perpendicular to the elements. perpendicular end-fire planar linear
end-fire
As the wave enters the dense layer of electrically charged ions, the part of the wave that enters the new medium first travels ______ than the parts of the wave that have not yet entered the new medium. None of the choices slower the same as faster
faster
In a single sideband transmitter, the _______ is in between the balanced modulator and the mixer. filter microphone radio frequency oscillator speech amplifier
filter
In character-oriented (or byte-oriented) framing, data to be carried are 8-bit characters from a coding system such as ASCII. To separate one frame from the next, an 8-bit (1-byte) ____ is added at the beginning and the end of a frame. flag spot guide marker
flag
If the antenna is too long for the transmitting frequency, it offers an _____ reactance. imaginary None of the choices inductive capacitive
inductive
In error detection and correction, whenever bits flow from one point to another, they are subject to unpredictable changes because of ______. overmodulation sporadic signal disturbance interference
interference
The distance travelled by ground waves: is less at higher frequencies depends on the maximum usable frequency is the same for all frequencies is more at higher frequencies
is less at higher frequencies
Losses occurring on a transmission line between transmitter and antenna results in: the wire radiating RF energy reflections occurring in the line less RF power being radiated an SWR reading of 1:1
less RF power being radiated
At the end of suspended antenna wire, insulators are used. These act to: prevent any loss of radio waves by the antenna increase the effective antenna length allow the antenna to be more easily held vertically limit the electrical length of the antenna
limit the electrical length of the antenna
In antennas, the points of high current and high voltage are known as current and voltage ____. troughs peaks field loops
loops
The grounded end of the quarter-wave antenna has a ___ input impedance and has ___ voltage and ___ current at the input end. low, low, high high, high, low high, low, high low, high, low
low, low, high
Atmospheric noise is greater at ______ frequencies; thus, radio waves may have an unacceptable signal-to-noise ratio. lower higher None of the choices the same
lower
In _______ transmission, all stations will receive the frame, the stations that are members of the group keep and handle it; the rest discard it. multicast broadcast All of the choices unicast
multicast
In a frequency modulation transmitter, the _______ is located between the modulator and the frequency multiplier. microphone oscillator speech amplifier power amplifier
oscillator
In a transmitter, excessive harmonics are produced by: overdriven stages low SWR resonant circuits a linear amplifier
overdriven stages
Microwaves need unidirectional antennas that send out signals in one direction. Two types of antennas are used for microwave communications: the ______ and the ______ parabolic dish, horn horn, aperture horn, whip aperture, parabolic dish
parabolic dish, horn
For a varying magnetic field to exist, it must form closed loops in _____ with the conductors and be _____ to the electric field. perpendicular, perpendicular parallel, perpendicular perpendicular, parallel parallel, parallel
parallel, perpendicular
In TCP/IP, the _____layer is responsible for carrying individual bits in a frame across the link. physical presentation application data link
physical
The group velocity of energy in a waveguide is determined by the _______ of the wavefronts off the "b" walls. rejection angle refraction angle reflection angle acceptance angle
reflection angle
In a Yagi-Uda 3 element directional antenna, the _______ is the longest radiating element. driven element reflector boom director
reflector
In a SSB transmission, the carrier is: transmitted with one sideband inserted at the transmitter of no use at the receiver reinserted at the receiver
reinserted at the receiver
A ______ is any space completely enclosed by conducting walls that can contain oscillating electromagnetic fields and possess resonant properties. None of the choices non-resonant cavity resonant cavity open cavity
resonant cavity
Close or direct contact with rf transmission lines or antennas may result in _____. These are usually deep, penetrating, third-degree burns. rf exposure rf shock rf burns rf radiation
rf burns
A switch in a datagram network uses a ______ that is based on the destination address. routing guide routing manuscript routing schedule routing guide
routing guide
The angle at which the receiving antenna must be aimed to capture the scattered energy is called the ______. scatter angle dispersion vector angle of dispersion angle of spreading
scatter angle
The resonant frequency of an antenna may be increased by: increasing the height of the radiating element lengthening the radiating element shortening the radiating element lowering the radiating element
shortening the radiating element
The optimum working frequency provides the best long range HF communication. Compared with the maximum usable frequency (MUF), it is usually: half the MUF slightly lower double the MUF slightly higher
slightly lower
An antenna changeover switch in a transmitter-receiver combination is necessary: to allow more than one transmitter to be used to prevent RF currents entering the receiver circuits to change antennas for operation on other frequencies so that one antenna can be used for transmitter and receiver
so that one antenna can be used for transmitter and receiver
In _____ we combine signals from different sources to fit into a larger bandwidth. It is designed to be used in wireless applications (LANs and WANs). random spectrum wide spectrum direct spectrum spread spectrum
spread spectrum
In any folded dipole, the increase of impedance is the ____ of the number of conductors used in the radiator. multiple difference sum square
square
The total bandwidth required for AM is _____ can be determined from the bandwidth of the audio signal. B_AM = 2B B_AM = 4B B_AM = 3B B_AM = 5B
B_AM = 2B
If the available channel is a _____ channel, we cannot send the digital signal directly to the channel; we need to convert the digital signal to an analog signal before transmission. Band-pass Band-stop High-pass Low-pass
Band-pass
The _____ of a composite signal is the difference between the highest and the lowest frequencies contained in that signal. Cycle Upper frequency Bandwidth Amplitude
Bandwidth
_____ transmission means sending a digital signal over a channel without changing the digital signal to an analog signal. Modulation Vocal Analog Baseband
Baseband
In decoding a digital signal, the receiver calculates a running average of the received signal power. This average is called the _____. Median Baseline Average Basic
Baseline
The ____ is the number of signal elements sent in 1s. The unit is the baud. Baud rate None of the choices Throughput Bitrate
Baud rate
Why might a dummy antenna get warm when in use? Because it stores radio waves Because it changes RF energy into heat Because it absorbs static electricity Because it stores electric current
Because it changes RF energy into heat
It is a horizontal, long-wire antenna designed especially for the reception and transmission of low-frequency, vertically polarized ground waves. Beverage antenna Direct antenna Isotropic antenna Whip antenna
Beverage antenna
The ____ defines the number of data elements (bits) sent in 1s. The unit is bits per second (bps). None of the choices Throughput Output Bit rate
Bit rate
The datagram networks are sometimes referred to as _____ networks. It means that the switch (packet switch) does not keep information about the connection state. Direct Peerless Portless Connectionless
Connectionless
The basic Marconi antenna is 1/4 wavelength long and is either grounded at one end or connected to a network of wires called a ______. Ground stall Anti-stall Counterpoise Director
Counterpoise
A receiver designed for SSB reception must have a BFO (beat frequency oscillator) because: it beats with the received carrier to produce the other sideband it reduces the passband of the IF stages it phases out the unwanted sideband signal the suppressed carrier must be replaced for detection
the suppressed carrier must be replaced for detection
If the frequency of a signal is decreased so much that two quarter-wavelengths are longer than the wide dimension of a waveguide, energy will no longer pass through the waveguide. This is the lower frequency limit or the _______ of a given waveguide. Base frequency Carrier wave None of the choices Cut-off frequency
Cut-off frequency
It refers to any sequence of events, such as the positive and negative alternations of a wave, comprising one cycle of electrical current. Frequency Amplitude Cycle Period
Cycle
In TCP/IP, the ____ layer takes a datagram and encapsulates it in a packet called a frame. Application Session Data link Network
Data link
______ functions include framing and flow and error control. Data link control Flow control Data check Data movement
Data link control
The _____ 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. Ping System Lag Delay
Delay
The losses resulting from the heating effect on the dielectric material between conductors. Hysteresis losses Eddy current losses Dielectric losses Copper losses
Dielectric losses
What encoding combines the ideas of RZ and NRZ-I? There is always a transition at the middle of the bit, but the bit values are determined at the beginning of the bit. If the next bit is 0, there is a transition; if the next bit is 1, there is none. Pulse position Pulse code Differential Manchester Skip
Differential Manchester
Although the actual bandwidth of a ____ signal is infinite, the effective bandwidth is finite. Digital Parallel Analog Mixed
Digital
______ is the process of changing one of the characteristics of an analog signal based on the information in digital data. Digital conversion Analog conversion Analog-to-digital conversion Digital-to-analog conversion
Digital-to-analog conversion
The basic Hertz antenna is 1/2 wavelength long at the operating frequency and is insulated from ground. It is often called a ______. Dipole Isenthalpic antenna Isotropic antenna Rubber ducky
Dipole
The _____is a device that provides a method of sampling energy from within a waveguide for measurement or use in another circuit. Directional coupler Directional binder Bidirectional binder Bidirectional coupler
Directional coupler
The refraction of light waves that causes the different frequencies to bend at slightly different angles. Aspersion Diffraction Dispersion Reflection
Dispersion
____ means that the signal changes its form or shape. t can occur in a composite signal made of different frequencies. Distortion Attenuation Disruption Change
Distortion
A proposed standard is elevated to ____ standard status after at least two successful independent and interoperable implementations. Barring difficulties, it normally becomes an Internet standard. Revised Proposed Possible Draft
Draft
What is the term for an antenna element that is supplied power from a transmitter through a transmission line? Director element. Parasitic element. Reflector element. Driven element.
Driven element.
What layer has the ability to refract signals as high as 20 megahertz and for this reason, it is valuable for communications in ranges up to about 1500 miles? D layer F layer E layer A layer
E layer
What do you call the expected information contained in a message? None of the choices Entropy Coded signal Efficiency
Entropy
The _____ RFCs either have been superseded by later specifications or have never passed the necessary maturity levels to become an Internet standard. Experimental Historic Informational Periodic
Historic
Waves that are radiated with their E field component parallel to the Earth's surface. Circularly polarized Vertically polarized Horizontally polarized Elliptically polarized
Horizontally polarized
Skin effect tends to ______ the effective resistance of the conductor. Increase None of the choices Decrease Maintain
Increase
As the frequency of a radio wave is lowered, the rate of refraction ______. So, a wave whose frequency is below the established LUF is refracted back to Earth at a shorter distance than desired. Increases Cannot be determined Decreases Remains the same
Increases
In transmission lines, power loss increases as resistance _______. Stays the same Decreases Increases Cannot be determined
Increases
A digital signal is a composite analog signal with an ____ bandwidth. Finite None of the choices Infinite Zero
Infinite
If a signal changes instantaneously, its frequency is ____. Low Infinite High Zero
Infinite
Sound ______ is a measure of the sound energy of a wave. Intensity Pitch Timbre Alto
Intensity
The _____is the technical advisor to the ISOC. The main purposes to oversee the continuing development of the TCP/IP Protocol Suite and to serve in a technical advisory capacity to research members of the Internet community. Internet Society Internet alliance Internet architecture board None of the choices
Internet architecture board
The ______is an international, nonprofit organization formed in 1992 to provide support for the Internet standards process. None of the choices Internet society WIFI alliance Internet alliance
Internet society
An _____ is a thoroughly tested specification that is useful to and adhered to by those who work with the Internet. It is a formalized regulation that must be followed. International standard Standard practice Internet standard None of the choices
Internet standard
The most important region of the atmosphere extending from 31 miles to 250 miles above the earth. Contains four cloud-like layers that affect radio waves. Hydrosphere Ionosphere Geosphere Biosphere
Ionosphere
Disturbances in the earth's magnetic field that make communications practical only at lower frequencies. Ionospheric storms None of the choices Magnetic clumping Ionic binding
Ionospheric storms
What metal plate contains an opening through which the waves may pass and are used to introduce inductance or capacitance into a waveguide? Iris Pupil Crevasse None of the choices
Iris
What ferrite rod device prevents the formation of reflected waves on a waveguide transmission line? SWR refractor. Reflector. Wave-trap. Isolator.
Isolator.
Some antenna sources radiate energy equally in all directions. Radiation of this type is known as _______. Isotropic radiation Direct radiation Cosmic radiation Isenthalpic radiation
Isotropic radiation
What happens to the feed point impedance of a ground-plane antenna when its radials are changed from horizontal to downward-sloping? It approaches zero. It decreases. It stays the same. It increases.
It increases.
In a ______ topology, each device has a dedicated point-to-point connection with only the two devices on either side of it. A signal is passed along in one direction, from device to device, until it reaches its destination. Ring Mesh Tree Star
Ring
In a pulse-position modulation system, what parameter does the modulating signal vary? The number of pulses per second. The duration of the pulses. The time at which each pulse occurs. Both the frequency and amplitude of the pulses.
The time at which each pulse occurs.
What factors limit the accuracy and stability of a frequency counter? Time base accuracy, speed of the logic and time base stability. Number of digits in the readout, external frequency reference and temperature coefficient of the logic. Number of digits in the readout, speed of the logic and time base stability. Time base accuracy, temperature coefficient of the logic and time base stability.
Time base accuracy, speed of the logic and time base stability.
A complete sine wave in the ____ domain can be represented by one single spike in the ____ domain. Time, frequency Frequency, amplitude Amplitude, frequency Frequency, time
Time, frequency
_____ is a digital multiplexing technique for combining several low-rate channels into one high-rate one. Time-division multiplexing Frequency-division multiplexing Space-division multiplexing None of the choices
Time-division multiplexing
_____ is a digital process that allows several connections to share the high bandwidth of a link. Frequency-division multiplexing None of the above Space-division multiplexing Time-division multiplexing
Time-division multiplexing
Time-division switching uses time-division multiplexing (TDM) inside a switch. The most popular technology is called the _________. Time-slot interchange Time-slot switch Time-slot allowance Time-slot bypass
Time-slot interchange
In TCP/IP, the _____ layer is responsible for giving services to the application layer: to get a message from an application program running on the source host and deliver it to the corresponding application program on the destination host. Transport Network Presentation Session
Transport
What geometric patterns will be displayed on an oscilloscope if the modulating audio is fed to the horizontal plates while the modulated RF is fed to the vertical plates, assume 100 % modulation? Triangle. Square. Line. Circle.
Triangle.
In waves, the peak of the negative alternation (maximum value below the line) is called the _______. Peak Crest Crescendo Trough
Trough
What is the capacity of the standard 4-kHz telephone channel with 30 dB S/N?
39846 bps
For most half-wave wire antennas, the radiation resistance is about_____. 73 ohms 35 ohms 65 ohms 85 ohms
65 ohms
For an Ethernet frame, a preamble, which is used to alert the receiving system to the coming frame and enable it to synchronize its clock if it's out of synchronization, consists of how many bytes of alternating 1's and 0's? 11 bytes 7 bytes 4 bytes 56 bytes
7 bytes
The FOT (frequency of optimum transmission) or OWF (optimum working frequency) is roughly about ______ percent of the MUF (maximum usable frequency) but the actual percentage varies. 85 90 50 75
85
A receive channel frequency is 872.4 MHz. To develop an 82.2 MHz IF, the frequency synthesizer must supply an LO signal of how much? 967.44 MHz 790.2 MHz 954.6 MHz 827.4 MHz
954.6 MHz
Energy may also be fed to the half-wave antenna by dividing the antenna at its center and connecting the transmission line from the final transmitter output stage to the two center ends of the halved antenna. This type of feed is known as the _______method. End-feed method Center-feed method None of the choices Voltage-feed method
Center-feed method
_____ carries signals of higher frequency ranges than those in twisted pair cable. Submarine cable Twin lead Waveguide Coaxial cable
Coaxial cable
What are more efficient than two-wire lines for transferring electromagnetic energy because the fields are completely confined by the conductors? Waveguides Twin lead Twisted pair Coaxial lines
Coaxial lines
In block coding, we divide our message into blocks, each of k bits, called datawords. We add r redundant bits to each block to make the length n = k + r. The resulting n bit blocks are called _____. Codewords Cypher Keywords Keys
Codewords
In antenna arrays, A _____ array is one in which all the elements lie in a straight line with no radiation at the ends of the array. Nonlinear Nonplanar Collinear Coplanar
Collinear
In data transmission, _____ means reducing the instantaneous voltage amplitude for large values. Encoding Compression Decoding Companding
Companding
A ____ signal is a signal made of many simple sine waves. Heterogeneous Composite Homogeneous Compound
Composite
A transmission line that has no standing waves. This line requires no special tuning device to transfer maximum power. Fiber optic cable Coaxial line Flat line Submarine cable
Flat line
The loss of energy of a radio wave because of the spreading of the wavefront as it travels from the transmitter. Dispersion loss Travelling loss Air loss Free space loss
Free space loss
In ______both stations can transmit and receive simultaneously. The full-duplex mode is used when communication in both directions is required all the time. The capacity of the channel, however, must be divided between the two directions. Simplex None of the choices Full duplex Half-duplex
Full duplex
For Yagi antennas, the greater number of parasitic elements used, the greater the _____. Gain Directivity Resistance Beamwidth
Gain
____ is a measure of the thickness of the wire. Thickness Width Gauge Length
Gauge
How can an antenna system be protected from lightning damage? Install a fuse in the antenna feed line Install a balun at the antenna feed point Install an RF choke in the antenna feed line Ground all antennas when they are not in use
Ground all antennas when they are not in use
A grounded quarter-wave antenna will resonate at the same frequency as an ungrounded half-wave antenna. This is because_______. Ground has low conductivity and acts as an electrical sponge Ground has high conductivity and acts as an electrical sponge Ground has high conductivity and acts as an electrical mirror image Ground has low conductivity and acts as an electrical mirror image
Ground has high conductivity and acts as an electrical mirror image
The loss of rf energy each time a radio wave is reflected from the Earth's surface. Sky wave loss Ground reflection loss Surface loss Earth absorption
Ground reflection loss
What media provide a conduit from one device to another, include twisted-pair cable, coaxial cable and fiber-optic cable? Unguided media Direct media Guided media Ungrounded media
Guided media
A _____ front-to-back ratio is desirable because this means that a minimum amount of energy is radiated in the undesired direction. Average None of the choices High Low
High
Frequency is the rate of change with respect to time. Change in a short span of time means ___ frequency. Infinite High Zero Low
High
What are some advantages of a Yagi with wide element spacing? High front-to-back ratio and lower input resistance High gain, lower loss and a low SWR Shorter boom length, lower weight and wind resistance High gain, less critical tuning and wider bandwidth
High gain, less critical tuning and wider bandwidth
The size of the skip distance depends on what 3 factors: (1) the velocity of the wave, (2) the angle of incidence, and (3) the degree of ionization present (1) the frequency of the wave, (2) the angle of incidence, and (3) the atmospheric layer used (1) the frequency of the wave, (2) the angle of incidence, and (3) the degree of ionization present (1) the velocity of the wave, (2) the angle of arrival, and (3) the degree of ionization present
(1) the frequency of the wave, (2) the angle of incidence, and (3) the degree of ionization present
The spacing between the elements on a three-element Yagi antenna, representing the best overall choice, is _______ of a wavelength. 0.2 0.15 0.75 0.5
0.2
Dimensions ranging from _______ are common for the "b" sides of a waveguide. 0.1 to 0.4 wavelength 0.5 to 0.7 wavelength 0.2 to 0.5 wavelength 0.05 to 0.3 wavelength
0.2 to 0.5 wavelength
The optimum gain of a broadside array is obtained when the elements are spaced ______ wavelength apart. 0.83 0.55 0.74 0.65
0.65
Because space waves are refracted slightly, even when propagated through the troposphere, the radio horizon is actually about ____ farther than the line-of-sight or natural horizon. 1/3 1/4 1/2 1/8
1/3
Raindrops cause greater attenuation by scattering than by absorption at frequencies above. 100 THz 100GHz 100 MHz 100 Hz
100 MHz
The radar range in nautical miles to an object can be found by measuring the elapsed time during a radar pulse and dividing this quantity by: 12.36 microseconds. 0.87 seconds. 1.73 microseconds. 1.15 microseconds.
12.36 microseconds.
The standing wave ratio is the measurement of maximum voltage (current) to minimum voltage (current) on a transmission line and measures the perfection of the termination of the line. A ratio of ________ describes a line terminated in its characteristic impedance. 3:1 2:1 1:2 1:1
1:1
Approximately how much gain does a half-wave dipole have over an isotropic radiator? 2.1 dB 6.0 dB 1.5 dB 3.0 dB
2.1 dB
What is the number of voice channels that can be accommodated for transmission in T1 carrier system? 56 64 24 32
24
Cavities with a Q value in excess of _____ are not uncommon. The high Q gives these devices a narrow bandpass and allows very accurate tuning. 50,000 30,000 20,000 10,000
30,000
When _______ is applied to an open-ended line, voltage is always reflected back in phase with the incident wave and current is reflected back out of phase. AC and DC AC DC Neither AC or DC
AC
To increase the resonant frequency of a 1/4 wavelength antenna: Add a capacitor. Add an inductor. Lower capacitor value. Cut antenna.
Add a capacitor.
What accepts an IP address from the IP protocol, maps the address to the corresponding link-layer address, and passes it to the data-link layer? Address recombination protocol Address resolution protocol None of the choices Address resetting protocol
Address resolution protocol
Eye pattern is: All of the choices Resembles the shape of human eye. Is used to study ISI. May be seen on CRO.
All of the choices
Probability density function defines: Probability of error. Amplitudes of random noise. Density of signal. All of the choices
Amplitudes of random noise.
FDM is an _____ multiplexing technique that combines analog signals. Parallel Serial Digital Analog
Analog
How is circular polarization produced using linearly polarized antennas? Arrange two Yagis perpendicular to each other, with the driven elements in the same plane, fed 90 degrees out of phase. Stack two Yagis, fed 90 degrees out of phase, to form an array with the respective elements in parallel planes. Arrange two Yagis perpendicular to each other, with the driven elements in the same plane, fed in phase. Stack two Yagis, fed in phase, to form an array with the respective elements in parallel planes.
Arrange two Yagis perpendicular to each other, with the driven elements in the same plane, fed 90 degrees out of phase.
An _____ is made up of more than one element, but the basic element is generally the dipole. Antenna assembly None of the choices Array antenna Antenna probe
Array antenna
In ______ transmission, the bits are still synchronized; their durations are the same. Synchronous Parallel Asynchronous Serial
Asynchronous
In ______ transmission, we send 1 start bit (0) at the beginning and 1 or more stop bits (1s) at the end of each byte. There may be a gap between bytes. Synchronous Asynchronous Serial Parallel
Asynchronous
_____ means a loss of energy. When a signal, simple or composite, travels through a medium, it loses some of its energy in overcoming the resistance of the medium. Susceptance Resistance Conductance Attenuation
Attenuation
Which of the following is not a Password Authentication Protocol (PAP) packet? Authenticate-nak Authenticate-send Authenticate-ack Authenticate-request
Authenticate-send
If the wave passes from a denser to a less dense medium, it is bent _____ from the normal, and the angle of refraction is greater than the angle of incidence. Almost parallel to Away Cannot be determined Toward
Away
An excited 1/2 wavelength antenna produces: An electro-flux field sometimes. An electro-magnetic field only. Residual fields. Both electro-magnetic and electro-static fields.
Both electro-magnetic and electro-static fields.
The "b" dimension of a waveguide is governed by the ________ of the dielectric, which is usually air. Dielectric constant Breakdown potential Propagation speed None of the choices
Breakdown potential
In error detection and correction, _____ means that 2 or more bits in the data unit have changed from 1 to 0 or from 0 to 1. Keying error Burst error Bit flip error Bust error
Burst error
A waveguide may be considered as having upper and lower quarter-wave sections and a central section which is a solid conductor called a _____. Bus bar Central hub Resistive element Concentrator
Bus bar
An RFC classified as ______ describes work related to an experimental situation that does not affect the operation of the Internet. Such an RFC should not be implemented in any functional Internet service. Historic Periodic Experimental Informational
Experimental
Structure and density of the _______ region depend on the time of day and the angle of the sun. This region consists of one layer during the night and splits into two layers during daylight hours. A E D F
F
Why does coaxial cable make a good antenna feed line? You can make it at home, and its impedance matches most amateur antennas It is weatherproof, and its impedance is higher than that of most amateur antennas It can be used near metal objects, and its impedance is higher than that of most amateur antennas It is weatherproof, and its impedance matches most amateur antennas
It is weatherproof, and its impedance matches most amateur antennas
What may happen if an FM transmitter is operated with the microphone gain or deviation control set too high? It may cause interference to other stations operating on a higher frequency band It may cause digital interference to computer equipment It may cause atmospheric interference in the air around the antenna It may cause interference to other stations operating near its frequency
It may cause interference to other stations operating near its frequency
A ______ is usually privately owned and connects some hosts in a single office, building, or campus. WAN Internet MAN LAN
LAN
Since any dielectric, even air, is not a perfect insulator, a small current known as _____ flows between the two wires. Dielectric current Majority current Leakage current None of the choices
Leakage current
What do you call the process of converting digital data to digital signals? Line coding Parallel coding None of the choices Serial coding
Line coding
In ____ propagation, very high-frequency signals are transmitted in straight lines directly from antenna to antenna. Antennas must be directional, facing each other, and either tall enough or close enough together not to be affected by the curvature of the earth. Wired Direct Beam Line of sight
Line of sight
The purpose of the _______ is to provide flow and error control for the upper-layer protocols that actually demand these services. Media Access Control (MAC) Internet Protocol (IP) Logical Link Control (LLC) Transmission Control Protocol (TCP)
Logical Link Control (LLC)
Since the ionized layers are often several miles thick, ionospheric reflection is more likely to occur at ____ wavelengths. Short Nanometer Random Long
Long
It is a type of wave motion in which the disturbance takes place in the direction of propagation of the wave. Longitudinal Wave Light Wave Transverse Wave Radio Wave
Longitudinal Wave
A sound having a long wavelength is heard at a ____ pitch (____ frequency). High Low Timbre Doubled
Low
Frequency is the rate of change with respect to time. Change over a long span of time means ___ frequency. Low Infinite Zero High
Low
What should you do for safety if you put up a UHF transmitting antenna? Make sure the antenna is near the ground to keep its RF energy pointing in the correct direction Make sure the antenna will be in a place where no one can get near it when you are transmitting Make sure that RF field screens are in place Make sure you connect an RF leakage filter at the antenna feed point
Make sure the antenna will be in a place where no one can get near it when you are transmitting
In _____ encoding, the duration of the bit is divided into two halves. The voltage remains at one level during the first half and moves to the other level in the second half. The transition at the middle of the bit provides synchronization. None of the choices non-return-to-zero return-to-zero Manchester
Manchester
For a given angle of incidence and time of day, there is a maximum frequency that can be used for communications between two given locations. This frequency is known as the _______. Critical frequency Carrier frequency Maximum usable frequency Inflection frequency
Maximum usable frequency
Upon recommendation from the Internet authorities, a draft may be published as a ______. Request for comment Request for columns Request for changes Request for coding
Request for comment
The reception and retransmission of radio waves caused by turbulence in the troposphere. Retransfer Reradiation Redistribution Redirection
Reradiation
A _____ line has standing waves of current and voltage and is of finite length and is not terminated in its characteristic impedance. Resonant Non-resonant Open-circuited Short-circuited
Resonant
The _______ is widely used for long-distance, high-frequency transmission and reception. It is one of the most popular fixed-station antennas because it is very useful in point-to-point communications. Rhombic antenna Elliptical antenna Rhomboid antenna Circular antenna
Rhombic antenna
_____ are used for unicast communication such as cellular telephones, satellite networks, and wireless LANs. Sky waves Ground waves Space waves Microwaves
Microwaves
In wave propagation, lower frequency waves tend to diffract ____ than higher frequency waves. Cannot be determined The same as More Less
More
A _______connection is one in which more than two specific devices share a single link. Direct Microwave Multidrop Point-to-point
Multidrop
_____ is so named because multiple beams from a light source move through the core in different paths. Single mode Multi beam Multimode None of the choices
Multimode
In______ fiber optic cable, the density of the core remains constant from the center to the edges. A beam of light moves through this constant density in a straight line until it reaches the interface of the core and the cladding.
Multimode step-index fiber
_____ is the set of techniques that allow the simultaneous transmission of multiple signals across a single data link. Selection Multiplexing Companding Compression
Multiplexing
NRZ-L and NRZ-I both have an average signal rate of ___ Bd. N N/8 N/2 N/4
N/2
Traditionally, a unipolar scheme was designed as a ______ scheme in which the positive voltage defines bit 1 and the zero voltage defines bit 0. NRZ Integral Differential None of the choices
NRZ
Traditionally, a unipolar scheme was designed as a ______ scheme in which the positive voltage defines bit 1 and the zero voltage defines bit 0. None of the choices Differential Integral NRZ
NRZ
Optical fibers are defined by the ratio of the diameter of their core to the diameter of their cladding, both expressed in_____. Picometers Nanometers Micrometers Meters
Nanometers
A ______ is the interconnection of a set of devices capable of communication.
Network
The MUF is highest around _____ when ultraviolet light waves from the sun are the most intense. Morning Evening Noon Night
Noon
What causes splatter interference? The transmitting antenna is the wrong length Signals from a transmitter`s output circuit are being sent back to its input circuit Keying a transmitter too fast Overmodulation of a transmitter
Overmodulation of a transmitter
A _____ element is located near the driven element from which it gets its power. It is placed close enough to the driven element to permit coupling. Driven Resistive Parasitic Passive
Parasitic
If the composite signal is _____, the decomposition gives a series of signals with discrete frequencies. Periodic Random Power Nonperiodic
Periodic
____ is a property of a wave that describes the position of the waveform relative to time 0. Phase Position Frequency Amplitude
Phase
The plane (vertical or horizontal) with respect to the earth in which the E field propagates. Planar axis Plane of polarization Plane of ionization Plane of electrification
Plane of polarization
What is transequatorial propagation? Propagation between two points at approximately the same distance north and south of the magnetic equator. Propagation between any two stations at the same latitude. Propagation between two continents by way of ducts along the magnetic equator. Propagation between two points on the magnetic equator.
Propagation between two points at approximately the same distance north and south of the magnetic equator.
_____ measures the time required for a bit to travel from the source to the destination. Arrival time Queuing time Propagation time Departure time
Propagation time
A _____ standard is a specification that is stable, well understood, and of sufficient interest to the Internet community. At this level, the specification is usually tested and implemented by several different groups. Revised Novel Stable Proposed
Proposed
The most common technique to change an analog signal to digital data (digitization) is called ______. Pulse position modulation Pulse position modulation Pulse code modulation Pulse width modulation
Pulse code modulation
What do you call the time needed for each intermediate or end device to hold the message before it can be processed? Propagation time Queuing time Arrival time Departure time
Queuing time
If you install a 6-meter Yagi antenna on a tower 50 meters from your transmitter, which of the following feed lines is best? RG-213 RG-58 RG-174 RG-59
RG-213
The losses that occur when magnetic lines of force about a conductor are projected into space as radiation and are not returned to the conductor as the cycle alternates. Non-returning power Stray Impedance Antenna impedance Radiation losses
Radiation losses
_____ are used for multicast communications, such as radio and television, and paging systems. None of the choices Radio waves Conical waves Beam waves
Radio waves
What are examples of transverse waves? Radio waves, light waves, and heat waves Sound waves, pressure waves, and light waves Radio waves, pressure waves, and heat waves Sound waves, light waves, and heat waves
Radio waves, light waves, and heat waves
The widest dimension of a waveguide is called the "a" dimension and determines the_______. Power-handling capability of the line Maximum frequency Range of operating frequencies Maximum multiplexed frequencies
Range of operating frequencies
The property of interchangeability of the same antenna for transmitting and receiving is known as antenna _______. Interchangeability Reciprocity Radiation Reflectivity
Reciprocity
It is defined as the position that a particle of matter would have if it were not disturbed by wave motion. Adjugated point Base Point Reference line Deferred line
Reference line
Waves traveling from the load back to the generator are called ________. Incident waves Direct waves Reflected waves Collector waves
Reflected waves
_____ transmission occurs in one of three ways: asynchronous, synchronous, and isochronous. Direct Serial Parallel Asynchronous
Serial
Type of transmission line that consists of parallel conductors separated from each other and surrounded by a solid dielectric. The conductors are contained within a braided copper tubing that acts as an electrical shield. Fiber optic cable Coaxial cable Twin lead Shielded pair
Shielded pair
In ______ mode, the communication is unidirectional, as on a one-way street. Only one of the two devices on a link can transmit; the other can only receive. Full duplex Simplex None of the choices Half-duplex
Simplex
At microwave frequencies, the current-carrying area of the inner conductor is restricted to a very small layer at the surface of the conductor by an action called _____. center moving skin effect jumping skin riding
Skin effect
The ______ is the distance from the transmitter to the point where the sky wave is first returned to Earth. Skip distance Jump distance Skip length Exclusion zone
Skip distance
In sound propagation, the higher the density of the medium, the _____ sound travels through it. Faster Hastier Swifter Slower
Slower
What influences all radiocommunication beyond ground-wave or line-of-sight ranges? The F1 region of the ionosphere Solar activity Lunar tidal effects The F2 region of the ionosphere
Solar activity
What causes the ionosphere to form? Solar radiation ionizing the outer atmosphere Release of fluorocarbons into the atmosphere Lightning ionizing the outer atmosphere Temperature changes ionizing the outer atmosphere
Solar radiation ionizing the outer atmosphere
In _____ switching, the paths in the circuit are separated from one another spatially. This technology was originally designed for use in analog networks but is used currently in both analog and digital networks. Space-division Time-division Frequency-division None of the choices
Space-division
In a multipoint environment, the capacity of the channel is shared. If several devices can use the link simultaneously, it is a ____ connection. Spatially shared Frequency shared Time shared None of the choices
Spatially shared
Irregular cloud-like patches of unusually high ionization. Often forms at heights near the normal E layer. Clumped E layer Sporadic F layer Clumped F layer Sporadic E layer
Sporadic E layer
Insulator used with transmission lines and antennas to keep the parallel wires separated. Breaker Sender Spreader Isolator
Spreader
The distribution of voltage and current formed by the incident and reflected waves which have minimum and maximum points on a resultant wave that appears to stand still. Standing wave Initial wave Incident wave Return wave
Standing wave
_____ in waveguides cause arcing which decreases the efficiency of energy transfer and can severely damage the waveguide. Absorbed waves Sitting waves Standing waves Running waves
Standing waves
An irregular ionospheric disturbance that can totally blank out hf radio communications. Sonic interference Sudden Ultrasonic Disturbance Sudden Ionospheric Disturbance Ionospheric waves
Sudden Ionospheric Disturbance
Seasonal variations of the D, E, and F1 layers correspond to the highest angle of the sun; thus the ionization density of these layers is greatest during ______. Winter Spring Fall Summer
Summer
_______ waves suffer most of their absorption losses because of ground-induced voltage. Solid Sky Surface Ground
Surface
In ______ transmission, we send bits one after another without start or stop bits or gaps. It is the responsibility of the receiver to group the bits. Asynchronous Serial Parallel Synchronous
Synchronous
What is the simplest of the commonly used waveguide junctions? T Junction D Junction B Junction X Junction
T Junction
An unusual situation develops in which layers of warm air are formed above layers of cool air. This condition is known as ______. Cool off Polarization inversion Temperature inversion Temperature swap
Temperature inversion
What does a very high SWR reading mean? The transmitter is putting out more power than normal, showing that it is about to go bad The antenna is the wrong length, or there may be an open or shorted connection somewhere in the feed line There is a large amount of solar radiation, which means very poor radio conditions The signals coming from the antenna are unusually strong, which means very good radio conditions
The antenna is the wrong length, or there may be an open or shorted connection somewhere in the feed line
Roll - off factor is defined as: None of the choices The bandwidth occupied beyond the Nyquist Bandwidth of the filter. Aliasing effect. The performance of the filter or device.
The bandwidth occupied beyond the Nyquist Bandwidth of the filter.
What term describes a method used to match a high-impedance transmission line to a lower impedance antenna by connecting the line to the driven element in two places, spaced a fraction of a wavelength on each side of the driven element center? The omega matching system. The gamma matching system. The delta matching system. The stub matching system.
The delta matching system.
What does horizontal wave polarization mean? The magnetic lines of force of a radio wave are parallel to the earth`s surface The electric lines of force of a radio wave are parallel to the earth`s surface The electric and magnetic lines of force of a radio wave are perpendicular to the earth`s surface The electric lines of force of a radio wave are perpendicular to the earth`s surface
The electric lines of force of a radio wave are parallel to the earth`s surface
Which of the following is true about connectionless protocol? No protocol is needed for acknowledging message reception No physical connection between two nodes All of the above The frames are not connected
The frames are not connected
What causes the ionosphere to absorb radio waves? The splitting of the F region The ionization of the D region The presence of ionized clouds in the E region The weather below the ionosphere
The ionization of the D region
A _______ is a bi-directional antenna used widely in military and commercial communications. Each conductor is fed with currents of opposite polarity. V antenna C antenna X antenna U antenna
V antenna
In overland communications, from approximately 50 to 100 MHz, ______ polarization results in a slightly stronger signal. Above 100 megahertz, the difference in signal strength is negligible between vertical and horizontal. Circular Vertical Horizontal Elliptical
Vertical
In _____ switching, all packets belonging to the same source and destination travel the same path, but the packets may arrive at the destination with different delays if resource allocation is on demand. Virtual-circuit Circuit Packet None of the choices
Virtual-circuit
What is an analog multiplexing technique to combine optical signals? None of the choices ADM WDM LWM
WDM
It can be defined as a recurring disturbance advancing through space with or without the use of a physical medium. It is, therefore, a means of moving or transferring energy from one point to another point.
Wave Motion
______ is often necessary to reduce reflections caused by a mismatch between the waveguide and the load. Waveguide impedance matching Waveguide capacitance matching Waveguide diameter matching Waveguide resistance match
Waveguide impedance matching
______ are coaxial lines without center conductors and are the most efficient way to transfer electromagnetic energy. Coaxial lines Waveguides Twisted pair Twin lead
Waveguides
It is the distance in space occupied by one cycle of a radio wave at any given instant. If the wave could be frozen in place and measured, it would be the distance from the leading edge of one cycle to the corresponding point on the next cycle. Wavelength Amplitude Frequency Period
Wavelength
It can be defined as a disturbance that moves through a medium (air, water, vacuum). Examples of which are sound, light and radio. Atoms Power Static Force Waves
Waves
If a signal does not change at all, its frequency is ____. Low High Zero Infinite
Zero
Most radiators emit (radiate) stronger radiation in one direction than in another. A radiator such as this is referred to as ______. isenthalpic anisotropic isotropic isobaric
anisotropic
In digital transmission, the ______ defines the number of bits that can fill the link. link capacity None of the choices link limit bandwidth-delay product
bandwidth-delay product
A _______connection provides a dedicated link between two devices. The entire capacity of the link is reserved for transmission between those two devices. Point-to-point Broadcast Multicast None of the choices
between two devices. The entire capacity of the link is reserved for transmission between those two devices. Point-to-point
A flexible coaxial line contains: only one conductor four or more conductors running parallel braid and insulation around a central conductor two parallel conductors separated by spacers
braid and insulation around a central conductor
In _______ transmission, all stations (except the sender) will receive the frame and all stations (except the sender) keep and handle it. broadcast unicast All of the choices multicast
broadcast
The usual effect of ionospheric storms is to: increase the maximum usable frequency produce extreme weather changes prevent communications by ground wave cause a fade-out of sky- wave signals
cause a fade-out of sky- wave signals
A _____ network is made of a set of switches connected by physical links, in which each link is divided into n channels. circuit-switched None of the choices router-switched packet-switched
circuit-switched
What commonly available antenna feed line can be buried directly in the ground for some distance without adverse effects? coaxial cable 600 ohm open-wire 300 ohm twin-lead 75 ohm twin-lead
coaxial cable
A _____ switch connects n inputs to m outputs in a grid, using electronic microswitches (transistors) at each cross point. cross-bus crosspoint crowbar crossbar
crossbar
For a short-circuited transmission line, the reflected _____ has the same polarity and the same amplitude as the incident current. frequency power voltage current
current
Switching at the _____ layer in a switched WAN is normally implemented by using virtual-circuit techniques. application data link network presentation
data link
In a ______ network, each packet is treated independently of all others. Even if a packet is part of a multipacket transmission, the network treats it as though it existed alone. datagram packet switch router
datagram
Adding a series inductance to an antenna would: have little effect increase the resonant frequency have no change on the resonant frequency decrease the resonant frequency
decrease the resonant frequency
The radiation field _____linearly as the distance from the antenna is increased. decreases None of the choices increases maintains
decreases
When a radio wave passing through the troposphere meets a turbulence, it makes an abrupt change in ______. velocity amplitude wavelength frequency
velocity
For a series-resonant circuit, at resonance the impedance is _______. A loss-free circuit has zero impedance (a short circuit). very high low high very low
very low
A ______network is a cross between a circuit-switched network and a datagram network. packet None of the choices virtual-circuit circuit
virtual-circuit
In NRZ-L the level of the ____ determines the value of the bit. voltage current phase frequency
voltage
The simplest method of feeding energy to the half-wave antenna is to connect one end through a capacitor to the final output stage of the transmitter. This method is called the ______. voltage-feed method None of the choices center-feed method current-feed method
voltage-feed method
If an antenna is correctly matched to a transmitter, the length of transmission line: must be an even number of half-waves will have no effect on the matching must be a full wavelength long must be an odd number of quarter-wave
will have no effect on the matching
