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Amateur Radio - Extra > E8 - SIGNALS AND EMISSIONS [4 Exam Questions - 4 Groups] > Flashcards

E8 - SIGNALS AND EMISSIONS [4 Exam Questions - 4 Groups] Flashcards

1
Q

What type of wave is made up of a sine wave plus all of its odd harmonics?

A. A square wave

B. A sine wave

C. A cosine wave

D. A tangent wave

A

A. A square wave

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2
Q

What type of wave has a rise time significantly faster than its fall time (or vice versa)?

A. A cosine wave

B. A square wave

C. A sawtooth wave

D. A sine wave

A

C. A sawtooth wave

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3
Q

What type of wave is made up of sine waves of a given fundamental frequency plus all its harmonics?

A. A sawtooth wave

B. A square wave

C. A sine wave

D. A cosine wave

A

A. A sawtooth wave

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4
Q

What is equivalent to the root-mean-square value of an AC voltage?

A. The AC voltage found by taking the square of the average value of the peak AC voltage

B. The DC voltage causing the same amount of heating in a given resistor as the corresponding peak AC voltage

C. The DC voltage causing the same amount of heating in a resistor as the corresponding RMS AC voltage

D. The AC voltage found by taking the square root of the average AC value

A

C. The DC voltage causing the same amount of heating in a resistor as the corresponding RMS AC voltage

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5
Q

What would be the most accurate way of measuring the RMS voltage of a complex waveform?

A. By using a grid dip meter

B. By measuring the voltage with a D’Arsonval meter

C. By using an absorption wavemeter

D. By measuring the heating effect in a known resistor

A

D. By measuring the heating effect in a known resistor

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6
Q

What is the approximate ratio of PEP-to-average power in a typical single-sideband phone signal?

A. 2.5 to 1

B. 25 to 1

C. 1 to 1

D. 100 to 1

A

A. 2.5 to 1

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7
Q

What determines the PEP-to-average power ratio of a single-sideband phone signal?

A. The frequency of the modulating signal

B. The characteristics of the modulating signal

C. The degree of carrier suppression

D. The amplifier gain

A

B. The characteristics of the modulating signal

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8
Q

What is the period of a wave?

A. The time required to complete one cycle

B. The number of degrees in one cycle

C. The number of zero crossings in one cycle

D. The amplitude of the wave

A

A. The time required to complete one cycle

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9
Q

What type of waveform is produced by human speech?

A. Sinusoidal

B. Logarithmic

C. Irregular

D. Trapezoidal

A

C. Irregular

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10
Q

Which of the following is a distinguishing characteristic of a pulse waveform?

A. Regular sinusoidal oscillations

B. Narrow bursts of energy separated by periods of no signal

C. A series of tones that vary between two frequencies

D. A signal that contains three or more discrete tones

A

B. Narrow bursts of energy separated by periods of no signal

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11
Q

What is one use for a pulse modulated signal?

A. Linear amplification

B. PSK31 data transmission

C. Multiphase power transmission

D. Digital data transmission

A

D. Digital data transmission

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12
Q

What type of information can be conveyed using digital waveforms?

A. Human speech

B. Video signals

C. Data

D. All of these choices are correct

A

D. All of these choices are correct

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13
Q

What is an advantage of using digital signals instead of analog signals to convey the same information?

A. Less complex circuitry is required for digital signal generation and detection

B. Digital signals always occupy a narrower bandwidth

C. Digital signals can be regenerated multiple times without error

D. All of these choices are correct

A

C. Digital signals can be regenerated multiple times without error

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14
Q

Which of these methods is commonly used to convert analog signals to digital signals?

A. Sequential sampling

B. Harmonic regeneration

C. Level shifting

D. Phase reversal

A

A. Sequential sampling

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15
Q

What would the waveform of a stream of digital data bits look like on a conventional oscilloscope?

A. A series of sine waves with evenly spaced gaps

B. A series of pulses with varying patterns

C. A running display of alpha-numeric characters

D. None of the above; this type of signal cannot be seen on a conventional oscilloscope

A

B. A series of pulses with varying patterns

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16
Q

What is the term for the ratio between the frequency deviation of an RF carrier wave, and the modulating frequency of its corresponding FM-phone signal?

A. FM compressibility

B. Quieting index

C. Percentage of modulation

D. Modulation index

A

D. Modulation index

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17
Q

How does the modulation index of a phase-modulated emission vary with RF carrier frequency (the modulated frequency)?

A. It increases as the RF carrier frequency increases

B. It decreases as the RF carrier frequency increases

C. It varies with the square root of the RF carrier frequency

D. It does not depend on the RF carrier frequency

A

D. It does not depend on the RF carrier frequency

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18
Q

What is the modulation index of an FM-phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency, when the modulating frequency is 1000 Hz?

A. 3

B. 0.3

C. 3000

D. 1000

A

A. 3

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19
Q

What is the modulation index of an FM-phone signal having a maximum carrier deviation of plus or minus 6 kHz when modulated with a 2-kHz modulating frequency?

A. 6000

B. 3

C. 2000

D. 1/3

A

B. 3

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20
Q

What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus-or-minus 5 kHz when the maximum modulation frequency is 3 kHz?

A. 60

B. 0.167

C. 0.6

D. 1.67

A

D. 1.67

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21
Q

What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus or minus 7.5 kHz when the maximum modulation frequency is 3.5 kHz?

A. 2.14

B. 0.214

C. 0.47

D. 47

A

A. 2.14

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22
Q

When using a pulse-width modulation system, why is the transmitter’s peak power greater than its average power?

A. The signal duty cycle is less than 100%

B. The signal reaches peak amplitude only when voice modulated

C. The signal reaches peak amplitude only when voltage spikes are generated within the modulator

D. The signal reaches peak amplitude only when the pulses are also amplitude modulated

A

A. The signal duty cycle is less than 100%

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23
Q

What parameter does the modulating signal vary in a pulse-position modulation system?

A. The number of pulses per second

B. The amplitude of the pulses

C. The duration of the pulses

D. The time at which each pulse occurs

A

D. The time at which each pulse occurs

24
Q

What is meant by deviation ratio?

A. The ratio of the audio modulating frequency to the center carrier frequency

B. The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency

C. The ratio of the carrier center frequency to the audio modulating frequency

D. The ratio of the highest audio modulating frequency to the average audio modulating frequency

A

B. The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency

25
Q

Which of these methods can be used to combine several separate analog information streams into a single analog radio frequency signal?

A. Frequency shift keying

B. A diversity combiner

C. Frequency division multiplexing

D. Pulse compression

A

C. Frequency division multiplexing

26
Q

Which of the following describes frequency division multiplexing?

A. The transmitted signal jumps from band to band at a predetermined rate

B. Two or more information streams are merged into a “baseband”, which then modulates the transmitter

C. The transmitted signal is divided into packets of information

D. Two or more information streams are merged into a digital combiner, which then pulse position modulates the transmitter

A

B. Two or more information streams are merged into a “baseband”, which then modulates the transmitter

27
Q

What is digital time division multiplexing?

A. Two or more data streams are assigned to discrete sub-carriers on an FM transmitter

B. Two or more signals are arranged to share discrete time slots of a data transmission

C. Two or more data streams share the same channel by transmitting time of transmission as the sub-carrier

D. Two or more signals are quadrature modulated to increase bandwidth efficiency

A

B. Two or more signals are arranged to share discrete time slots of a data transmission

28
Q

Which one of the following digital codes consists of elements having unequal length?

A. ASCII

B. AX.25

C. Baudot

D. Morse code

A

D. Morse code

29
Q

What are some of the differences between the Baudot digital code and ASCII?

A. Baudot uses four data bits per character, ASCII uses seven or eight; Baudot uses one character as a shift code, ASCII has no shift code

B. Baudot uses five data bits per character, ASCII uses seven or eight; Baudot uses two characters as shift codes, ASCII has no shift code

C. Baudot uses six data bits per character, ASCII uses seven or eight; Baudot has no shift code, ASCII uses two characters as shift codes

D. Baudot uses seven data bits per character, ASCII uses eight; Baudot has no shift code, ASCII uses two characters as shift codes

A

B. Baudot uses five data bits per character, ASCII uses seven or eight; Baudot uses two characters as shift codes, ASCII has no shift code

30
Q

What is one advantage of using the ASCII code for data communications?

A. It includes built-in error-correction features

B. It contains fewer information bits per character than any other code

C. It is possible to transmit both upper and lower case text

D. It uses one character as a shift code to send numeric and special characters

A

C. It is possible to transmit both upper and lower case text

31
Q

What technique is used to minimize the bandwidth requirements of a PSK31 signal?

A. Zero-sum character encoding

B. Reed-Solomon character encoding

C. Use of sinusoidal data pulses

D. Use of trapezoidal data pulses

A

C. Use of sinusoidal data pulses

32
Q

What is the necessary bandwidth of a 13-WPM international Morse code transmission?

A. Approximately 13 Hz

B. Approximately 26 Hz

C. Approximately 52 Hz

D. Approximately 104 Hz

A

C. Approximately 52 Hz

33
Q

What is the necessary bandwidth of a 170-hertz shift, 300-baud ASCII transmission?

A. 0.1 Hz

B. 0.3 kHz

C. 0.5 kHz

D. 1.0 kHz

A

C. 0.5 kHz

34
Q

What is the necessary bandwidth of a 4800-Hz frequency shift, 9600-baud ASCII FM transmission?

A. 15.36 kHz

B. 9.6 kHz

C. 4.8 kHz

D. 5.76 kHz

A

A. 15.36 kHz

35
Q

What term describes a wide-bandwidth communications system in which the transmitted carrier frequency varies according to some predetermined sequence?

A. Amplitude compandored single sideband

B. AMTOR

C. Time-domain frequency modulation

D. Spread-spectrum communication

A

D. Spread-spectrum communication

36
Q

Which of these techniques causes a digital signal to appear as wide-band noise to a conventional receiver?

A. Spread-spectrum

B. Independent sideband

C. Regenerative detection

D. Exponential addition

A

A. Spread-spectrum

37
Q

What spread-spectrum communications technique alters the center frequency of a conventional carrier many times per second in accordance with a pseudo-random list of channels?

A. Frequency hopping

B. Direct sequence

C. Time-domain frequency modulation

D. Frequency compandored spread-spectrum

A

A. Frequency hopping

38
Q

What spread-spectrum communications technique uses a high speed binary bit stream to shift the phase of an RF carrier?

A. Frequency hopping

B. Direct sequence

C. Binary phase-shift keying

D. Phase compandored spread-spectrum

A

B. Direct sequence

39
Q

What is the advantage of including a parity bit with an ASCII character stream?

A. Faster transmission rate

B. The signal can overpower interfering signals

C. Foreign language characters can be sent

D. Some types of errors can be detected

A

D. Some types of errors can be detected

40
Q

What is one advantage of using JT-65 coding?

A. Uses only a 65 Hz bandwidth

B. The ability to decode signals which have a very low signal to noise ratio

C. Easily copied by ear if necessary

D. Permits fast-scan TV transmissions over narrow bandwidth

A

B. The ability to decode signals which have a very low signal to noise ratio

41
Q

Which of the following is the easiest voltage amplitude parameter to measure when viewing a pure sine wave signal on an analog oscilloscope?

A. Peak-to-peak voltage

B. RMS voltage

C. Average voltage

D. DC voltage

A

A. Peak-to-peak voltage

42
Q

What is the relationship between the peak-to-peak voltage and the peak voltage amplitude of a symmetrical waveform?

A. 0.707:1

B. 2:1

C. 1.414:1

D. 4:1

A

B. 2:1

43
Q

What input-amplitude parameter is valuable in evaluating the signal-handling capability of a Class A amplifier?

A. Peak voltage

B. RMS voltage

C. Average power

D. Resting voltage

A

A. Peak voltage

44
Q

What is the PEP output of a transmitter that develops a peak voltage of 30 volts into a 50-ohm load?

A. 4.5 watts

B. 9 watts

C. 16 watts

D. 18 watts

A

B. 9 watts

45
Q

If an RMS-reading AC voltmeter reads 65 volts on a sinusoidal waveform, what is the peak-to-peak voltage?

A. 46 volts

B. 92 volts

C. 130 volts

D. 184 volts

A

D. 184 volts

46
Q

What is the advantage of using a peak-reading wattmeter to monitor the output of a SSB phone transmitter?

A. It is easier to determine the correct tuning of the output circuit

B. It gives a more accurate display of the PEP output when modulation is present

C. It makes it easier to detect high SWR on the feed line

D. It can determine if any flat-topping is present during modulation peaks

A

B. It gives a more accurate display of the PEP output when modulation is present

47
Q

What is an electromagnetic wave?

A. Alternating currents in the core of an electromagnet

B. A wave consisting of two electric fields at right angles to each other

C. A wave consisting of an electric field and a magnetic field oscillating at right angles to each other

D. A wave consisting of two magnetic fields at right angles to each other

A

C. A wave consisting of an electric field and a magnetic field oscillating at right angles to each other

48
Q

Which of the following best describes electromagnetic waves traveling in free space?

A. Electric and magnetic fields become aligned as they travel

B. The energy propagates through a medium with a high refractive index

C. The waves are reflected by the ionosphere and return to their source

D. Changing electric and magnetic fields propagate the energy

A

D. Changing electric and magnetic fields propagate the energy

49
Q

What is meant by circularly polarized electromagnetic waves?

A. Waves with an electric field bent into a circular shape

B. Waves with a rotating electric field

C. Waves that circle the Earth

D. Waves produced by a loop antenna

A

B. Waves with a rotating electric field

50
Q

What type of meter should be used to monitor the output signal of a voice-modulated single-sideband transmitter to ensure you do not exceed the maximum allowable power?

A. An SWR meter reading in the forward direction

B. A modulation meter

C. An average reading wattmeter

D. A peak-reading wattmeter

A

D. A peak-reading wattmeter

51
Q

What is the average power dissipated by a 50-ohm resistive load during one complete RF cycle having a peak voltage of 35 volts?

A. 12.2 watts

B. 9.9 watts

C. 24.5 watts

D. 16 watts

A

A. 12.2 watts

52
Q

What is the peak voltage of a sinusoidal waveform if an RMS-reading voltmeter reads 34 volts?

A. 123 volts

B. 96 volts

C. 55 volts

D. 48 volts

A

D. 48 volts

53
Q

Which of the following is a typical value for the peak voltage at a standard U.S. household electrical outlet?

A. 240 volts

B. 170 volts

C. 120 volts

D. 340 volts

A

B. 170 volts

54
Q

Which of the following is a typical value for the peak-to-peak voltage at a standard U.S. household electrical outlet?

A. 240 volts

B. 120 volts

C. 340 volts

D. 170 volts

A

C. 340 volts

55
Q

Which of the following is a typical value for the RMS voltage at a standard U.S. household electrical power outlet?

A. 120V AC

B. 340V AC

C. 85V AC

D. 170V AC

A

A. 120V AC

56
Q

What is the RMS value of a 340-volt peak-to-peak pure sine wave?

A. 120V AC

B. 170V AC

C. 240V AC

D. 300V AC

A

A. 120V AC

Amateur Radio - Extra (10 decks)

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