Subelements 6, 8, and 9 comprise only 25% of the test.

Signals and Emissions

E8A01 (C)Starting at a positive peak, how many times does a sine wave cross the zero axis in one complete cycle?

C. 2 times

E8A02 (C)What is a wave called that abruptly changes back and forth between two voltage levels and remains an equal time at each level?

C. A square wave

E8A03 (D)What sine waves added to a fundamental frequency make up a square wave?

D. All odd harmonics

E8A04 (A)What type of wave is made up of a sine wave of a fundamental frequency and all its odd harmonics?

A. A square wave

E8A05 (B)What is a sawtooth wave?

B. A wave with a straight line rise time faster than the fall time (or vice versa)

E8A06 (C)What type of wave has a rise time significantly faster than the fall time (or vice versa)?

C. A sawtooth wave

E8A07 (A)What type of wave is made up of sine waves of a fundamental frequency and all harmonics?

A. A sawtooth wave

E8A08 (B)What is the peak voltage at a common household electrical outlet?

B. 170 volts

E8A09 (C)What is the peak-to-peak voltage at a common household electrical outlet?

C. 340 volts

E8A10 (A)What is the RMS voltage at a common household electrical power outlet?

A. 120-V AC

E8A11 (A)What is the RMS value of a 340-volt peak-to-peak pure sine wave?

A. 120-V AC

E8A12 (C)What is the equivalent to the root-mean-square value of an AC voltage?

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

E8A13 (D)What would be the most accurate way of measuring the RMS voltage of a complex waveform?

D. By measuring the heating effect in a known resistor

E8A14 (A)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?

A. 2.5 to 1

E8A15 (B)In a single-sideband phone signal, what determines the PEP-to-average power ratio?

B. The speech characteristics

E8A16 (C)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?

C. 2500 watts

E8A17 (C)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?

C. 1000 watts

E8A18 (A)What is the period of a wave?

A. The time required to complete one cycle

E8B01 (A)What is emission A3C?

A. Facsimile

E8B02 (B)What type of emission is produced when an AM transmitter is modulated by a facsimile signal?

B. A3C

E8B03 (C)What does a facsimile transmission produce?

C. Printed pictures by electrical means

E8B04 (D)What is emission F3F?

D. Television

E8B05 (D)What type of emission is produced when an SSB transmitter is modulated by a slow-scan television signal?

D. J3F

E8B06 (B)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?

B. The type of modulation of the main carrier

E8B07 (C)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?

C. The nature of signals modulating the main carrier

E8B08 (D)If the third symbol of an ITU emission designator is D, representing data transmission, telemetry or telecommand, what information about the emission is described?

D. The type of information to be transmitted

E8B10 (D)How does the modulation index of a phase-modulated emission vary with RF carrier frequency (the modulated frequency)?

D. It does not depend on the RF carrier frequency

E8B11 (A)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?

A. 3

E8B12 (B)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?

B. 3

E8B13 (D)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?

D. 1.67

E8B14 (A)In a pulse width-modulation system, why is the transmitter's peak power much greater than its average power?

A. The signal duty cycle is less than 100%

E8B15 (C)What is one way that voice is transmitted in a pulse-width modulation system?

C. A standard pulse is varied in duration by an amount depending on the voice waveform at that instant

E8B17 (C)Which of the following describe the three most-used symbols of an ITU emission designator?

C. Type of modulation, nature of the modulating signal and type of information to be transmitted

E8B18 (D)If the first symbol of an ITU emission designator is G, representing a phase-modulated signal, what information about the emission is described?

D. The type of modulation of the main carrier

E8B19 (D)In a pulse-position modulation system, what parameter does the modulating signal vary?

D. The time at which each pulse occurs

E8B20 (B)In a pulse-width modulation system, what parameter does the modulating signal vary?

B. Pulse duration

E8B21 (A)How are the pulses of a pulse-modulated signal usually transmitted?

A. A pulse of relatively short duration is sent; a relatively long period of time separates each pulse

E8B22 (D)In an FM-phone signal, what is the term for the ratio between the deviation of the frequency modulated signal and the modulating frequency?

D. Modulation index

E8B23 (B)What is meant by deviation ratio?

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

E8B24 (A) 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?

A. 2.14

E8C01 (D)What digital code consists of elements having unequal length?

D. Morse code

E8C02 (B)What are some of the differences between the Baudot digital code and ASCII?

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

E8C03 (C)What is one advantage of using the ASCII code for data communications?

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

E8C04 (B)What digital communications system is well suited for meteor-scatter Communications at times other than during meteor showers?

B. Computerized high speed CW (HSCW)

E8C05 (D)What type of error control system does Mode A AMTOR use?

D. The receiving station automatically requests repeats when needed

E8C06 (A)What type of error control system does Mode B AMTOR use?

A. Each character is sent twice

E8C07 (C)What is the necessary bandwidth of a 13-WPM international Morse code emission A1A transmission?

C. Approximately 52 Hz

E8C08 (C)What is the necessary bandwidth for a 170-hertz shift, 300-baud ASCII emission J2D transmission?

C. 0.5 kHz

E8C09 (D)What is the necessary bandwidth of a 1000-Hz shift, 1200-baud ASCII emission F1D transmission?

D. 2400 Hz

E8C10 (A)What is the necessary bandwidth of a 4800-Hz frequency shift, 9600-baud ASCII emission F1D transmission?

A. 15.36 kHz

E8C11 (D)What term describes a wide-bandwidth communications system in which the RF carrier varies according to some predetermined sequence?

D. Spread-spectrum communication

E8C12 (A)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

E8C13 (B)What spread-spectrum communications technique uses a very fast binary bit stream to shift the phase of an RF carrier?

B. Direct sequence

E8C14 (C)What controls the spreading sequence of an amateur spread-spectrum transmission?

C. A binary linear-feedback shift register

E8C15 (D)What makes spread-spectrum communications resistant to interference?

D. Only signals using the correct spreading sequence are received

E8C16 (B)What reduces interference from spread-spectrum transmitters to conventional communications in the same band?

B. Spread-spectrum signals appear only as low-level noise in conventional receivers

E8D01 (D)What is the term for the amplitude of the maximum positive excursion of a signal as viewed on an oscilloscope?

D. Peak positive voltage

E8D02 (A)What is the easiest voltage amplitude dimension to measure by viewing a pure sine wave signal on an oscilloscope?

A. Peak-to-peak voltage

E8D03 (B)What is the relationship between the peak-to-peak voltage and the peak voltage amplitude in a symmetrical waveform?

B. 2:1

E8D04 (A)What input-amplitude parameter is valuable in evaluating the signal-handling capability of a Class A amplifier?

A. Peak voltage

E8D05 (B)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?

B. 9 watts

E8D06 (D)If an RMS reading AC voltmeter reads 65 volts on a sinusoidal waveform, what is the peak-to-peak voltage?

D. 184 volts

E8D07 (A)What is the advantage of using a peak-reading voltmeter to monitor the output of a single-sideband transmitter?

A. It would be easy to calculate the PEP output of the transmitter

E8D08 (C)What is an electromagnetic wave?

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

E8D09 (D)Which of the following best describes electromagnetic waves traveling in free space?

D. Changing electric and magnetic fields propagate the energy across a vacuum

E8D10 (B)What is meant by circularly polarized electromagnetic waves?

B. Waves with a rotating electric field

E8D11 (D)What is the polarization of an electromagnetic wave if its magnetic field is parallel to the surface of the Earth?

D. Vertical

E8D12 (A)What is the polarization of an electromagnetic wave if its magnetic field is perpendicular to the surface of the Earth?

A. Horizontal

E8D13 (D)What is the primary source of noise that can be heard in an HF-band receiver with an antenna connected?

D. Atmospheric noise

E8D14 (A)At approximately what speed do electromagnetic waves travel in free space?

A. 300 million meters per second

E8D15 (D)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?

D. A peak-reading wattmeter

E8D16 (A)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

E8D17 (D)If an RMS reading voltmeter reads 34 volts on a sinusoidal waveform, what is the peak voltage?

D. 48 volts