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Amateur Radio Question PoolsNew! View the differences between the 2008 Extra question pool and the previous pool. Amateur Extra Class Question PoolPrev 1 2 3 4 5 6 7 8 9 0 NextE8A01 Starting at a positive peak, how many times does a sine wave cross the zero axis in one complete cycle? 180 times 4 times 2 times 360 times E8A02 What is a wave called that abruptly changes back and forth between two voltage levels and remains an equal time at each level? A sine wave A cosine wave A square wave A sawtooth wave E8A03 What sine waves added to a fundamental frequency make up a square wave? A sine wave 0.707 times the fundamental frequency All odd and even harmonics All even harmonics All odd harmonics E8A04 What type of wave is made up of a sine wave of a fundamental frequency and all its odd harmonics? A square wave A sine wave A cosine wave A tangent wave E8A05 What is a sawtooth wave? A wave that alternates between two values and spends an equal time at each level A wave with a straight line rise time faster than the fall time (or vice versa) A wave that produces a phase angle tangent to the unit circle A wave whose amplitude at any given instant can be represented by a point on a wheel rotating at a uniform speed E8A06 What type of wave has a rise time significantly faster than the fall time (or vice versa)? A cosine wave A square wave A sawtooth wave A sine wave E8A07 What type of wave is made up of sine waves of a fundamental frequency and all harmonics? A sawtooth wave A square wave A sine wave A cosine wave E8A08 What is the peak voltage at a common household electrical outlet? 240 volts 170 volts 120 volts 340 volts E8A09 What is the peak-to-peak voltage at a common household electrical outlet? 240 volts 120 volts 340 volts 170 volts E8A10 What is the RMS voltage at a common household electrical power outlet? 120-V AC 340-V AC 85-V AC 170-V AC E8A11 What is the RMS value of a 340-volt peak-to-peak pure sine wave? 120-V AC 170-V AC 240-V AC 300-V AC E8A12 What is the equivalent to the root-mean-square value of an AC voltage? The AC voltage found by taking the square of the average value of the peak AC voltage The DC voltage causing the same heating in a given resistor as the peak AC voltage The DC voltage causing the same heating in a given resistor as the RMS AC voltage of the same value The AC voltage found by taking the square root of the average AC value E8A13 What would be the most accurate way of measuring the RMS voltage of a complex waveform? By using a grid dip meter By measuring the voltage with a D'Arsonval meter By using an absorption wavemeter By measuring the heating effect in a known resistor E8A14 For many types of voices, what is the approximate ratio of PEP to average power during a modulation peak in a single-sideband phone signal? 2.5 to 1 25 to 1 1 to 1 100 to 1 E8A15 In a single-sideband phone signal, what determines the PEP-to-average power ratio? The frequency of the modulating signal The speech characteristics The degree of carrier suppression The amplifier power E8A16 What is the approximate DC input power to a Class B RF power amplifier stage in an FM-phone transmitter when the PEP output power is 1500 watts? 900 watts 1765 watts 2500 watts 4500 watts E8A17 What is the approximate DC input power to a Class AB RF power amplifier stage in an unmodulated carrier transmitter when the PEP output power is 500 watts? 250 watts 600 watts 1000 watts 1500 watts E8A18 What is the period of a wave? The time required to complete one cycle The number of degrees in one cycle The number of zero crossings in one cycle The amplitude of the wave E8B01 What is emission A3C? Facsimile RTTY ATV Slow Scan TV E8B02 What type of emission is produced when an AM transmitter is modulated by a facsimile signal? A3F A3C F3F F3C E8B03 What does a facsimile transmission produce? Tone-modulated telegraphy A pattern of printed characters designed to form a picture Printed pictures by electrical means Moving pictures by electrical means E8B04 What is emission F3F? Modulated CW Facsimile RTTY Television E8B05 What type of emission is produced when an SSB transmitter is modulated by a slow-scan television signal? J3A F3F A3F J3F E8B06 If the first symbol of an ITU emission designator is J, representing a single-sideband, suppressed-carrier signal, what information about the emission is described? The nature of any signal multiplexing The type of modulation of the main carrier The maximum permissible bandwidth The maximum signal level, in decibels E8B07 If the second symbol of an ITU emission designator is 1, representing a single channel containing quantized, or digital information, what information about the emission is described? The maximum transmission rate, in bauds The maximum permissible deviation The nature of signals modulating the main carrier The type of information to be transmitted E8B08 If the third symbol of an ITU emission designator is D, representing data transmission, telemetry or telecommand, what information about the emission is described? The maximum transmission rate, in bauds The maximum permissible deviation The nature of signals modulating the main carrier The type of information to be transmitted E8B10 How does the modulation index of a phase-modulated emission vary with RF carrier frequency (the modulated frequency)? It increases as the RF carrier frequency increases It decreases as the RF carrier frequency increases It varies with the square root of the RF carrier frequency It does not depend on the RF carrier frequency E8B11 In an FM-phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency, what is the modulation index when the modulating frequency is 1000 Hz? 3 0.3 3000 1000 E8B12 What is the modulation index of an FM-phone transmitter producing a maximum carrier deviation of 6 kHz when modulated with a 2-kHz modulating frequency? 6000 3 2000 1/3 E8B13 What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus or minus 5 kHz and accepting a maximum modulation rate of 3 kHz? 60 0.167 0.6 1.67 E8B14 In a pulse width-modulation system, why is the transmitter's peak power much greater than its average power? The signal duty cycle is less than 100% The signal reaches peak amplitude only when voice modulated The signal reaches peak amplitude only when voltage spikes are generated within the modulator The signal reaches peak amplitude only when the pulses are also amplitude modulated E8B15 What is one way that voice is transmitted in a pulse-width modulation system? A standard pulse is varied in amplitude by an amount depending on the voice waveform at that instant The position of a standard pulse is varied by an amount depending on the voice waveform at that instant A standard pulse is varied in duration by an amount depending on the voice waveform at that instant The number of standard pulses per second varies depending on the voice waveform at that instant E8B17 Which of the following describe the three most-used symbols of an ITU emission designator? Type of modulation, transmitted bandwidth and modulation code designator Bandwidth of the modulating signal, nature of the modulating signal and transmission rate of signals Type of modulation, nature of the modulating signal and type of information to be transmitted Power of signal being transmitted, nature of multiplexing and transmission speed E8B18 If the first symbol of an ITU emission designator is G, representing a phase-modulated signal, what information about the emission is described? The nature of any signal multiplexing The maximum permissible deviation The nature of signals modulating the main carrier The type of modulation of the main carrier E8B19 In a pulse-position modulation system, what parameter does the modulating signal vary? The number of pulses per second Both the frequency and amplitude of the pulses The duration of the pulses The time at which each pulse occurs E8B20 In a pulse-width modulation system, what parameter does the modulating signal vary? Pulse frequency Pulse duration Pulse amplitude Pulse intensity E8B21 How are the pulses of a pulse-modulated signal usually transmitted? A pulse of relatively short duration is sent; a relatively long period of time separates each pulse A pulse of relatively long duration is sent; a relatively short period of time separates each pulse A group of short pulses are sent in a relatively short period of time; a relatively long period of time separates each group A group of short pulses are sent in a relatively long period of time; a relatively short period of time separates each group E8B22 In an FM-phone signal, what is the term for the ratio between the deviation of the frequency modulated signal and the modulating frequency? FM compressibility Quieting index Percentage of modulation Modulation index E8B23 What is meant by deviation ratio? The ratio of the audio modulating frequency to the center carrier frequency The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency The ratio of the carrier center frequency to the audio modulating frequency The ratio of the highest audio modulating frequency to the average audio modulating frequency E8B24 What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus or minus 7.5 kHz and accepting a maximum modulation rate of 3.5 kHz? 2.14 0.214 0.47 47 E8C01 What digital code consists of elements having unequal length? ASCII AX.25 Baudot Morse code E8C02 What are some of the differences between the Baudot digital code and ASCII? Baudot uses four data bits per character, ASCII uses seven; Baudot uses one character as a shift code, ASCII has no shift code Baudot uses five data bits per character, ASCII uses seven; Baudot uses two characters as shift codes, ASCII has no shift code Baudot uses six data bits per character, ASCII uses seven; Baudot has no shift code, ASCII uses two characters as shift codes Baudot uses seven data bits per character, ASCII uses eight; Baudot has no shift code, ASCII uses two characters as shift codes E8C03 What is one advantage of using the ASCII code for data communications? It includes built-in error-correction features It contains fewer information bits per character than any other code It is possible to transmit both upper and lower case text It uses one character as a shift code to send numeric and special characters E8C04 What digital communications system is well suited for meteor-scatter Communications at times other than during meteor showers? ACSSB Computerized high speed CW (HSCW) AMTOR Spread spectrum E8C05 What type of error control system does Mode A AMTOR use? Each character is sent twice The receiving station checks the calculated frame check sequence(FCS) against the transmitted FCS The receiving station checks the calculated frame parity against the transmitted parity The receiving station automatically requests repeats when needed E8C06 What type of error control system does Mode B AMTOR use? Each character is sent twice The receiving station checks the calculated frame check sequence(FCS) against the transmitted FCS The receiving station checks the calculated frame parity against the computer-sequencing clock The receiving station automatically requests repeats when needed E8C07 What is the necessary bandwidth of a 13-WPM international Morse code emission A1A transmission? Approximately 13 Hz Approximately 26 Hz Approximately 52 Hz Approximately 104 Hz E8C08 What is the necessary bandwidth for a 170-hertz shift, 300-baud ASCII emission J2D transmission? 0 Hz 0.3 kHz 0.5 kHz 1.0 kHz E8C09 What is the necessary bandwidth of a 1000-Hz shift, 1200-baud ASCII emission F1D transmission? 1000 Hz 1200 Hz 440 Hz 2400 Hz E8C10 What is the necessary bandwidth of a 4800-Hz frequency shift, 9600-baud ASCII emission F1D transmission? 15.36 kHz 9.6 kHz 4.8 kHz 5.76 kHz E8C11 What term describes a wide-bandwidth communications system in which the RF carrier varies according to some predetermined sequence? Amplitude compandored single sideband AMTOR Time-domain frequency modulation Spread-spectrum communication E8C12 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? Frequency hopping Direct sequence Time-domain frequency modulation Frequency compandored spread-spectrum E8C13 What spread-spectrum communications technique uses a very fast binary bit stream to shift the phase of an RF carrier? Frequency hopping Direct sequence Binary phase-shift keying Phase compandored spread-spectrum E8C14 What controls the spreading sequence of an amateur spread-spectrum transmission? A frequency-agile linear amplifier A crystal-controlled filter linked to a high-speed crystal switching mechanism A binary linear-feedback shift register A binary code which varies if propagation changes E8C15 What makes spread-spectrum communications resistant to interference? Interfering signals are removed by a frequency-agile crystal filter Spread-spectrum transmitters use much higher power than conventional carrier-frequency transmitters Spread-spectrum transmitters can hunt for the best carrier frequency to use within a given RF spectrum Only signals using the correct spreading sequence are received E8C16 What reduces interference from spread-spectrum transmitters to conventional communications in the same band? A spread-spectrum transmitter avoids channels within the band which are in use by conventional transmitters Spread-spectrum signals appear only as low-level noise in conventional receivers Spread-spectrum signals change too rapidly to be detected by conventional receivers Special crystal filters are needed in conventional receivers to detect spread-spectrum signals E8D01 What is the term for the amplitude of the maximum positive excursion of a signal as viewed on an oscilloscope? Peak-to-peak voltage Inverse peak negative voltage RMS voltage Peak positive voltage E8D02 What is the easiest voltage amplitude dimension to measure by viewing a pure sine wave signal on an oscilloscope? Peak-to-peak voltage RMS voltage Average voltage DC voltage E8D03 What is the relationship between the peak-to-peak voltage and the peak voltage amplitude in a symmetrical waveform? 1:1 2:1 3:1 4:1 E8D04 What input-amplitude parameter is valuable in evaluating the signal handling capability of a Class A amplifier? Peak voltage RMS voltage An average reading power output meter Resting voltage E8D05 What is the PEP output of a transmitter that has a maximum peak of 30 volts to a 50-ohm load as observed on an oscilloscope? 4.5 watts 9 watts 16 watts 18 watts E8D06 If an RMS reading AC voltmeter reads 65 volts on a sinusoidal waveform, what is the peak-to-peak voltage? 46 volts 92 volts 130 volts 184 volts E8D07 What is the advantage of using a peak-reading voltmeter to monitor the output of a single-sideband transmitter? It would be easy to calculate the PEP output of the transmitter It would be easy to calculate the RMS output power of the transmitter It would be easy to calculate the SWR on the transmission line It would be easy to observe the output amplitude variations E8D08 What is an electromagnetic wave? Alternating currents in the core of an electromagnet A wave consisting of two electric fields at right angles to each other A wave consisting of an electric field and a magnetic field at right angles to each other A wave consisting of two magnetic fields at right angles to each other E8D09 Which of the following best describes electromagnetic waves traveling in free space? Electric and magnetic fields become aligned as they travel The energy propagates through a medium with a high refractive index The waves are reflected by the ionosphere and return to their source Changing electric and magnetic fields propagate the energy across a vacuum E8D10 What is meant by circularly polarized electromagnetic waves? Waves with an electric field bent into a circular shape Waves with a rotating electric field Waves that circle the Earth Waves produced by a loop antenna E8D11 What is the polarization of an electromagnetic wave if its magnetic field is parallel to the surface of the Earth? Circular Horizontal Elliptical Vertical E8D12 What is the polarization of an electromagnetic wave if its magnetic field is perpendicular to the surface of the Earth? Horizontal Circular Elliptical Vertical E8D13 What is the primary source of noise that can be heard in an HF-band receiver with an antenna connected? Detector noise Induction motor noise Receiver front-end noise Atmospheric noise E8D14 At approximately what speed do electromagnetic waves travel in free space? 300 million meters per second 468 million meters per second 186,300 feet per second 300 million miles per second E8D15 To ensure you do not exceed the maximum allowable power, what kind of meter would you use to monitor the output signal of a properly adjusted single-sideband transmitter? An SWR meter reading in the forward direction A modulation meter An average reading wattmeter A peak-reading wattmeter E8D16 What is the average power dissipated by a 50-ohm resistive load during one complete RF cycle having a peak voltage of 35 volts? 12.2 watts 9.9 watts 24.5 watts 16 watts E8D17 If an RMS reading voltmeter reads 34 volts on a sinusoidal waveform, what is the peak voltage? 123 volts 96 volts 55 volts 48 volts |
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