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Flashcards in Chapter 1 - Tomasi Deck (65):
1

Who discovered the electromagnetic waves?

Heinrich Hertz

2

Who discovered the radio waves?

Heinrich Hertz

3

Who developed the superheterodyne radio receiver?

Major Edwin Armstrong

4

Who invented and demonstrated the television?

Vladimir Zworykin

5

Who patented the wide-band frequency modulation?

Major Edwin Armstrong

6

What does FCC stands for?

Federal Communications Commission

7

________ was created to regulate telephone, radio and television broadcasting.

FCC

8

What is the FM signal range?

88MHz to 108MHz

9

What country launched the world's first satellite and what is its name?

Russia, Sputnik

10

These are time-varying voltage or current waves.

Analog signals

11

Is sometimes referred to as a power loss.

Attenuation

12

Is sometimes referred to as a ________ , If Pout = Pin, the absolute power gain is 1, and the dB power gain is 0 dB.

Unity Power Gain

13

Are voltages or currents that change in discrete steps or levels.

Digital Signals

14

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.

Telephone

15

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.

Transmitter

16

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

Medium

17

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

Reciever

18

Is any unwanted electrical signals that interfere with the information signal.

System Noise

19

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 ______.

Carrier

20

The process of changing one or more signals of the analog carrier in proportion with the information signal.

Modulation

21

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

AM

22

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

FM

23

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

PM

24

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

Amplitude Shift Keying ( ASK )

25

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

Frequency Shift Keying ( FSK )

26

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

Phase Shift Keying ( PSK )

27

Modulation is performed in a transmitter by a circuit called ________.

Modulator

28

The reverse process of modulation and converts the modulated carrier back to the original information

Demodulation

29

Is an international agency in control of allocating frequencies and services within the overall frequency spectrum.

International Telecommunications Union ( ITU )

30

Are signals in the 30Hz to 300Hz range and include ac power distribution signals (60Hz) and low frequency telemetry signals.

Extremely Low Frequencies ( ELF )

31

Are signals in the 300Hz to 3000Hz range and include frequencies generally associated with human speech.

Voice Frequencies ( VF )

32

Are signals in the 3kHz to 30kHz range which include the upper end of the human hearing range.

Very Low Frequencies ( VLF )

33

Are signals in the 30kHz to 300kHz range and are used primarily for marine and aeronautical navigation.

Low Frequencies ( LF )

34

Are signals in the 300kHz to 3MHz range and are used primarily for commercial AM radio broadcasting (535kHz-1605kHz).

Medium Frequencies ( MF )

35

Are signals in the 3MHz to 30MHz range and are often referred to as short waves. Used for most two-way radio communications.

High Frequencies ( HF )

36

Are signals in the 30MHz to 300MHz range and are used for mobile radio, marine and aeronautical communications, commercial FM broadcasting (88 to 108MHz) and commercial TV broadcasting of Ch 2 to 13 (54MHz to 216MHz).

Very High Frequencies ( VHF )

37

Are signals in the 300MHz to 3GHz range and are used by commercial television broadcasting of channels 14 to 83, land mobile communications services, cellular telephones, certain radar and navigation systems, and microwave and satellite radio systems.

Ultrahigh Frequencies ( UHF )

38

Are signals in the 3GHz to 30GHz range and include the majority of the frequencies used for microwave and satellite radio communications systems.

Super High Frequencies ( SHF )

39

Are signals in the 30GHz to 300GHz range and are seldom used for radio communications except in very sophisticated, expensive, and specialized applications.

Extremely High Frequencies ( EHF )

40

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.

Infrared

41

Includes electromagnetic frequencies that fall within the visible range of humans (0.3PHz to 3PHz).

Visible Light

42

The two most significant limitations on the performance of a communications system are ________and ________.

Noise and Bandwidth

43

The difference between the highest and lowest frequencies contained in the information.

The difference between the highest and lowest frequencies contained in the information.

44

Any undesirable electrical energy that falls within the passband of the signal.

Electrical Noise

45

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

Uncorrelated Noise

46

Noise that is generated outside the device or circuit.

External Noise

47

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

Atmospheric Noise

48

Atmospheric noise is commonly called ____________ .

Static Electricity

49

Noise consists of electrical signals that originate from outside Earth’s atmosphere and is sometimes called deep-space noise.

Extraterrestrial Noise

50

Extraterrestrial noise is sometimes called ____________ .

Deep-Space Noice

51

Noise generated directly from the sun’s heat.

Solar Noise

52

Noise sources that are continuously distributed throughout the galaxies.

Cosmic Noise

53

Noise that is produced by mankind.

Man-made Noise

54

Electrical interference generated within a device or circuit.

Internal Noise

55

Noise caused by the random arrival of carriers (holes and electrons) at the output element of an electronic device.

Shot Noise

56

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

Transit-time Noise

57

Associated with the rapid and random movement of electrons within a conductor due to thermal agitation.

Thermal Noise

58

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! “

Correlated Noise

59

Occurs when unwanted harmonics of a signal are produced through nonlinear amplification (nonlinear mixing).

Harmonic Distortion

60

Another name for harmonic distortion.

Amplitude Distortion

61

A form of external noise and as the name implies it means to disturb or detract form.

Interference

62

The ratio of the signal power level to the noise power level.

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

63

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

Noise Factor ( F ) and Noise Figure ( NF )

64

What is the formula for noise factor?

A image thumb
65

What is the formula for noise figure?

A image thumb