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ECE141 Electronic Communication > Prelim > Flashcards

Prelim Flashcards

1
Q

Are time-varying voltages or currents that are continuously

changing such as sine and cosine waves.

A

analog signals

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2
Q

Is sometimes referred to as a power loss.

A

Attenuation

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3
Q

Is sometimes referred to as a ____________ , If Pout = Pin,

the absolute power gain is 1, and the dB power gain is 0 dB.

A

Unity Power Gain

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4
Q

Are voltages or currents that change in discrete steps or

levels.

A

digital signals

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5
Q

In 1876, Alexander Graham Bell and Thomas A. Watson were the
first to successfully transfer human conversation over a crude metallic- wire
communications systems using this device.

A

Telephone

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6
Q

The first commercial radio broadcasting station in 1920 that

broadcasted amplitude modulated signals in Pittsburgh.

A

KDKA

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7
Q

Is a logarithmic unit that can be used to measure ratio.

A

Decibel ( dB )

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8
Q

Is a unit of measurement used to indicate the ratio of a power
level with respect to a fixed reference level (1mW).

A

dBm

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9
Q

One-tenth of a decibel.

A

Bel

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10
Q

A collection of one or more electronic devices or circuits
that converts the original source information to a form more suitable for
transmission over a particular transmission medium.

A

Transmitter

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11
Q

Provides a means of transporting signals between a transmitter
and a receiver.

A

Transmission Medium

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12
Q

Its fundamental purpose is to transfer information from one

place to another.

A

Electronic Communication System

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13
Q

The transmission, reception, and processing of information

between two or more locations using electronic circuits.

A

Electronic Communication

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14
Q

A collection of electronic devices and circuits that accepts
the transmitted signals for the transmission medium and then converts those
signals back to their original form.

A

Receiver

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15
Q

Is any unwanted electrical signals that interfere with the

information signal.

A

System Noise

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16
Q

Because it is often impractical to propagate information
signals over standard transmission media, it is often necessary to modulate
the source information onto a higher-frequency analog signal called a

A

Carrier

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17
Q

The process of changing one or more properties of the analog

carrier in proportion with the information signal.

A

Modulation

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18
Q

A system in which energy is transmitted and received in analog
form (a continuously varying signals such as a sine wave).

A

Analog Communication System

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19
Q

A true digital system where digital pulses (discrete levels
such as +5V and ground) are transferred between two or more points in a
communications system.

A

Digital Transmission

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20
Q

The transmittal of digitally modulated analog carriers between
two or more points in a communications system.

A

digital radio

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21
Q

A modulation technique where the information signal is analog
and the amplitude (V) of the carrier is varied proportional to the
information signal.

A

Amplitude Modulation ( AM )

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22
Q

A modulation technique where the information signal is analog
and the frequency (f) of the carrier is varied proportional to the
information signal.

A

Frequency Modulation ( FM )

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23
Q

A modulation technique where the information signal is analog
and the phase (q) of the carrier is varied proportional to the information
signal.

A

Phase Modulation

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24
Q

A modulation technique where the information signal is digital
and that amplitude (V) of the carrier is varied proportional to the
information signal.

A

Amplitude Shift Keying ( ASK )

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25
Q

A modulation technique where the information signal is digital
and the frequency (f) of the carrier is varied proportional to the
information signal.

A

Frequency Shift Keying ( FSK )

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26
Q

A modulation technique where the information signal is digital
and the phase (q) of the carrier is varied proportional to the information
signal.

A

Phase Shift Keying

PSK

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27
Q

A modulation technique where both the amplitude and the phase
of the carrier are varied proportional to the information signal.

A

Quadrature Amplitude Modulation

QAM

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28
Q

Modulation is performed in a transmitter by a circuit called

A

Modulator

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29
Q

The reverse process of modulation and converts the modulated

carrier back to the original information.

A

Demodulation

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30
Q

Demodulation is performed in a receiver by a circuit called

A

Demodulator

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31
Q

2 Reasons why modulation is necessary in

electronic communications :

A
  1. It is extremely difficult to radiate low-frequency signals
    from an antenna in the form of electromagnetic energy.
  2. Information signals often occupy the same frequency band
    and, if signals from two or more sources are transmitted at the same time,
    they would interfere with each other.
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32
Q

A specific band of frequencies allocated a particular service.

A

Channel

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33
Q

Process of converting a frequency or band of frequencies to

another location in the total frequency spectrum.

A

Frequency Translation

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34
Q

The purpose of an electronic communications system is to

communicate information between two or more locations commonly called

A

Stations

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35
Q

The number of times a periodic motion, such as a sine wave of
voltage or current, occurs in a given period of time.

A

Frequency

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36
Q

Each complete alternation of the waveform.

A

Cycle

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37
Q

Is an international agency in control of allocating

frequencies and services within the overall frequency spectrum.

A

International Telecommunications Union (

ITU)

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38
Q

Are signals in the 0.3THz to 300THz range and are not
generally referred to as radio waves. Used in heat seeking guidance systems,
electronic photography, and astronomy.

A

Infrared

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39
Q

Includes electromagnetic frequencies that fall within the

visible range of humans (0.3PHz to 3PHz).

A

Visible Light

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40
Q

Used for optical fiber systems.

A

Light-wave Communications

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41
Q

The length that one cycle of an electromagnetic wave occupies
in space

A

Wavelength

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42
Q

Radio transmitter classifications according to bandwidth,

modulation scheme, and type of information.

A

Emission Classifications

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43
Q

The two most significant limitations on the performance of a

communications system are ________and ________.

A

Noise and Bandwidth

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44
Q

The difference between the highest and lowest frequencies

contained in the information.

A

Bandwidth

45
Q

The bandwidth of a communications channel is the difference
between the highest and lowest frequencies that the channel will allow to
pass through it.

A

Passband

46
Q

A highly theoretical study of the efficient use of bandwidth

to propagate information through electronic communications systems.

A

Information Theory

47
Q

The measure of how much information can be propagated through
a communications system and is a function of bandwidth and transmission time.

A

Information Capacity

48
Q

The most basic digital symbol used to represent information.

A

Binary Digit / Bit

49
Q

The number of bits transmitted during one second and is

expressed in bits per second (bps).

A

Bit Rate

50
Q

In 1948, mathematician Claude E. Shannon published a paper in
the Bell System Technical Journal relating the information capacity of a
communications channel to bandwidth and signal-to-noise ratio.

A

Shannon limit for information capacity

51
Q

In 1948, mathematician Claude E. Shannon published a paper in
the Bell System Technical Journal relating the information capacity of a
communications channel to bandwidth and signal-to-noise ratio.

A

Shannon limit for information capacity

52
Q

I = Blog2(1+S/N)

A

Shannon limit for information capacity

53
Q

Any undesirable electrical energy that falls within the

passband of the signal.

A

Electrical Noise

54
Q

Noise present regardless of whether there is a signal present
or not.

A

Uncorrelated Noise

55
Q

Noise that is generated outside the device or circuit.

A

External Noise

56
Q

Noise that is naturally occurring electrical disturbances that
originate within Earth’s atmosphere.

A

Atmospheric Noise

57
Q

Atmospheric noise is commonly called

A

Static Electricity

58
Q

Noise consists of electrical signals that originate from

outside Earth’s atmosphere and is sometimes called deep-space noise.

A

Extraterrestrial Noise

59
Q

Extraterrestrial noise is sometimes called

A

Deep-Space Noise

60
Q

Noise generated directly from the sun’s heat.

A

Solar Noise

61
Q

Noise sources that are continuously distributed throughout the
galaxies.

A

Cosmic Noise

62
Q

Noise that is produced by mankind.

A

Man-made Noise

63
Q

Electrical interference generated within a device or circuit.

A

Internal Noise

64
Q

Noise caused by the random arrival of carriers (holes and

electrons) at the output element of an electronic device.

A

Shot Noise

65
Q

Any modification to a stream of carriers as they pass from the
input to the output of a device produces an irregular, random variations.

A

Transit-time Noise

66
Q

Associated with the rapid and random movement of electrons

within a conductor due to thermal agitation

A

Thermal Noise

67
Q

THERMAL AGITATION HAS SEVERAL NAMES,

INCLUDING :

A

Ø Thermal Noise, because it is temperature dependent;
Ø Brownian Noise, after its discoverer;
Ø Johnson Noise, after the man who related Brownian particle
movement of electron movement;
Ø White Noise, because the random movement is at all
frequencies;

68
Q

Johnson proved that ___________ is proportional to the

product of bandwidth and temperature.

A

Noise Power

69
Q

Noise Power Formula

A

N = KTB

70
Q

A form of internal noise that is correlated (mutually related)
to the signal and cannot be present in a circuit unless there is a signal. “
no signal, no noise! “

A

Correlated Noise

71
Q

Noise that is only present with the signal.

A

Correlated Noise

72
Q

Occurs when unwanted harmonics of a signal are produced

through nonlinear amplification (nonlinear mixing).

A

Harmonic Distortion

73
Q

The generation of unwanted sum and difference frequencies

produced when two or more signals mix in a nonlinear device.

A

Inter-modulation Distortion

74
Q

The original signal is called

A

Fundamental Frequency

75
Q

Fundamental Frequency is also called

A

First Harmonic

76
Q

A frequency two times the original signal frequency.

A

Second Harmonic

77
Q

A frequency three times the original signal frequency.

A

Third Harmonic

78
Q

Another name for harmonic distortion.

A

Amplitude Distortion

79
Q

Characterized by high-amplitude peaks of short duration in the
total noise spectrum.

A

Impulse Noise

80
Q

A form of external noise and as the name implies it means to

disturb or detract form.

A

Interference

81
Q

Noise produced when information signals from one source
produce frequencies that fall outside their allocated bandwidth and interfere
with information signals from another source.

A

Electrical interference

82
Q

he ratio of the signal power level to the noise power level

A

Signal-to-Noise Power Ratio ( S/N )

83
Q

Figures of merit used to indicate how much the signal –
to-noise ratio deteriorates as a signal passes through a circuit or series of
circuits (unitless)

A

Noise Factior (F)

84
Q

Figures of merit used to indicate how much the signal –
to-noise ratio deteriorates as a signal passes through a circuit or series of
circuits (dB)

A

Noise Figure (NF)

85
Q

Formula for Noise Figure (NF)

A

10logF

86
Q

A convenient parameter often used rather than noise figure in
low noise, sophisticated VHF, UHF, microwave, and satellite radio receivers.
It indicates the reduction in the signal-to-noise ratio a signal undergoes as
it propagates through a receiver.

A

Equivalent Noise Temperature
( Te )
Te = T ( F – 1 )

87
Q

Transfer information from one place to another

A

Electronic Communications System

88
Q

Transmission, reception and processing of information between two or more locations using electronic circuits

A

Electronic Communications System

89
Q

broadcast first licensed radio transmission

A

KDKA

90
Q

Use to measure magnitude of earthquakes, intensity of acoustical signals, power ratios, voltage and current ratios, etc.

A

DECIBEL (dB)

91
Q

A transmission-measuring unit used to express relative gains and losses of electronic devices and circuits

A

DECIBEL (dB)

92
Q

The measurement unit of choice for virtually all EM frequency bands from ultralow frequencies to light-wave frequencies terminated in a variety of impedances

A

dBm

93
Q

A process of changing one or more properties of an analog carrier in proportion with the information signal

A

Modulation and Demodulation

94
Q

is an information signal that has been acted on by a carrier

A

MODULATED WAVE/MODULATED SIGNAL

95
Q

Why do we need to MODULATE???

A

It is extremely difficult to radiate low-frequency signals from an antenna in the form of EM energy &
Information signals often occupy the same frequency band and if signals from two or more sources are transmitted at the same time, they would interfere with each other

96
Q

Band Number and Designation of a 30 Hz to 300 Hz frequencies

A

BN: 2

Extremely Low Frequencies (ELF)

97
Q

Band Number and Designation of a 0.3 kHz to 3 kHz frequencies

A 
BN: 3
Voice Frequencies (VF)
98
Q

Band Number and Designation of a 3 kHz to 30 kHz frequencies

A

BN: 4

Very Low Frequencies (VLF)

99
Q

Band Number and Designation of a 30 kHz to 300 kHz frequencies

A

BN: 5

Low Frequencies

100
Q

Band Number and Designation of 0.3 MHz to 3 MHz frequencies

A

BN: 6

Medium Frequencies

101
Q

Band Number and Designation of 3MHz to 30 MHz frequencies

A

BN: 7

High Freqencies

102
Q

30 MHz to 300 MHz

A

8

Very High Frequencies (VHF)

103
Q

300 MHz to 3 GHz

A

9

Ultra High Frequencies (UHF)

104
Q

3 GHz to 30 GHz

A

10

Super High Frequencies (SHF)

105
Q

30 GHz to 300 GHz

A

11

Extremely High Frequencies (EHF)

106
Q

Ambient Absolute Temperature (T)

A

290K

107
Q

Friiss’ Formula

A

FT(Total Noise Factor) = F1 + (F2-1)/A1 + (F3-1)/A1A2 + … +(Fn-1)/A1A2…An

108
Q

Noise Factor Formula

A

F = (inp SNR/outp SNR

109
Q

Noise Figure Formula

A

NF = 10logF

ECE141 Electronic Communication (4 decks)

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