All 48 Ham Radio Amateur Extra questions for E8 Signals & Emissions with the correct answers marked, from the official 2024-2028 question pool. Test yourself with the free practice exam.
E8A01
What technique shows that a square wave is made up of a sine wave and its odd harmonics?
A. Fourier analysis ✓
B. Vector analysis
C. Numerical analysis
D. Differential analysis
E8A02
Which of the following is a type of analog-to-digital conversion?
A. Successive approximation ✓
B. Harmonic regeneration
C. Level shifting
D. Phase reversal
E8A03
Which of the following describes a signal in the time domain?
A. Power at intervals of phase
B. Amplitude at different times ✓
C. Frequency at different times
D. Discrete impulses in time order
E8A04
What is “dither” with respect to analog-to-digital converters?
A. An abnormal condition where the converter cannot settle on a value to represent the signal
B. A small amount of noise added to the input signal to reduce quantization noise ✓
C. An error caused by irregular quantization step size
D. A method of decimation by randomly skipping samples
E8A05
What is the benefit of making voltage measurements with a true-RMS calculating meter?
A. An inverse Fourier transform can be used
B. The signal’s RMS noise factor is also calculated
C. The calculated RMS value can be converted directly into phasor form
D. RMS is measured for both sinusoidal and non-sinusoidal signals ✓
E8A06
What is the approximate ratio of PEP-to-average power in an unprocessed single-sideband phone signal?
A. 2.5 to 1 ✓
B. 25 to 1
C. 1 to 1
D. 13 to 1
E8A07
What determines the PEP-to-average power ratio of an unprocessed single-sideband phone signal?
A. The frequency of the modulating signal
B. Speech characteristics ✓
C. The degree of carrier suppression
D. Amplifier gain
E8A08
Why are direct or flash conversion analog-to-digital converters used for a software defined radio?
A. Very low power consumption decreases frequency drift
B. Immunity to out-of-sequence coding reduces spurious responses
C. Very high speed allows digitizing high frequencies ✓
D. All these choices are correct
E8A09
How many different input levels can be encoded by an analog-to-digital converter with 8-bit resolution?
A. 8
B. 8 multiplied by the gain of the input amplifier
C. 256 divided by the gain of the input amplifier
D. 256 ✓
E8A10
What is the purpose of a low-pass filter used at the output of a digital-to-analog converter?
A. Lower the input bandwidth to increase the effective resolution
B. Improve accuracy by removing out-of-sequence codes from the input
C. Remove spurious sampling artifacts from the output signal ✓
D. All these choices are correct
E8A11
Which of the following is a measure of the quality of an analog-to-digital converter?
A. Total harmonic distortion ✓
B. Peak envelope power
C. Reciprocal mixing
D. Power factor
E8B01
What is the modulation index of an FM signal?
A. The ratio of frequency deviation to modulating signal frequency ✓
B. The ratio of modulating signal amplitude to frequency deviation
C. The modulating signal frequency divided by the bandwidth of the transmitted signal
D. The bandwidth of the transmitted signal divided by the modulating signal frequency
E8B02
How does the modulation index of a phase-modulated emission vary with RF carrier 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 ✓
E8B03
What is the modulation index of an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency if the highest modulating frequency is 1000 Hz?
A. 3 ✓
B. 0.3
C. 6
D. 0.6
E8B04
What is the modulation index of an FM phone signal having a maximum carrier deviation of plus or minus 6 kHz if the highest modulating frequency is 2 kHz?
A. 0.3
B. 3 ✓
C. 0.6
D. 6
E8B05
What is the deviation ratio of an FM phone signal having a maximum frequency swing of plus or minus 5 kHz if the highest modulation frequency is 3 kHz?
A. 6
B. 0.167
C. 0.6
D. 1.67 ✓
E8B06
What is the deviation ratio of an FM phone signal having a maximum frequency swing of plus or minus 7.5 kHz if the highest modulation frequency is 3.5 kHz?
A. 2.14 ✓
B. 0.214
C. 0.47
D. 47
E8B07
Orthogonal frequency-division multiplexing (OFDM) is a technique used for which types of amateur communication?
A. Digital modes ✓
B. Extremely low-power contacts
C. EME
D. OFDM signals are not allowed on amateur bands
E8B08
What describes orthogonal frequency-division multiplexing (OFDM)?
A. A frequency modulation technique that uses non-harmonically related frequencies
B. A bandwidth compression technique using Fourier transforms
C. A digital mode for narrow-band, slow-speed transmissions
D. A digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference ✓
E8B09
What is 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
E8B10
What is frequency division multiplexing (FDM)?
A. The transmitted signal jumps from band to band at a predetermined rate
B. Dividing the transmitted signal into separate frequency bands that each carry a different data stream ✓
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
E8B11
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
E8C01
What is Quadrature Amplitude Modulation or QAM?
A. A technique for digital data compression used in digital television which removes redundancy in the data by comparing bit amplitudes
B. Transmission of data by modulating the amplitude of two carriers of the same frequency but 90 degrees out of phase ✓
C. A method of performing single sideband modulation by shifting the phase of the carrier and modulation components of the signal
D. A technique for analog modulation of television video signals using phase modulation and compression
E8C02
What is the definition of symbol rate in a digital transmission?
A. The number of control characters in a message packet
B. The maximum rate at which the forward error correction code can make corrections
C. The rate at which the waveform changes to convey information ✓
D. The number of characters carried per second by the station-to-station link
E8C03
Why should the phase of a PSK signal be changed at the zero crossing of the RF signal?
A. To minimize bandwidth ✓
B. To simplify modulation
C. To improve carrier suppression
D. All these choices are correct
E8C04
What technique minimizes the bandwidth of a PSK31 signal?
A. Zero-sum character encoding
B. Reed-Solomon character encoding
C. Use of sinusoidal data pulses ✓
D. Use of linear data pulses
E8C05
What is the approximate bandwidth of a 13-WPM International Morse Code transmission?
A. 13 Hz
B. 26 Hz
C. 52 Hz ✓
D. 104 Hz
E8C06
What is the bandwidth of an FT8 signal?
A. 10 Hz
B. 50 Hz ✓
C. 600 Hz
D. 2.4 kHz
E8C07
What is the bandwidth of a 4,800-Hz frequency shift, 9,600-baud ASCII FM transmission?
A. 15.36 kHz ✓
B. 9.6 kHz
C. 4.8 kHz
D. 5.76 kHz
E8C08
How does ARQ accomplish error correction?
A. Special binary codes provide automatic correction
B. Special polynomial codes provide automatic correction
C. If errors are detected, redundant data is substituted
D. If errors are detected, a retransmission is requested ✓
E8C09
Which digital code allows only one bit to change between sequential code values?
A. Binary Coded Decimal Code
B. Extended Binary Coded Decimal Interchange Code
C. Extended ASCII
D. Gray code ✓
E8C10
How can data rate be increased without increasing bandwidth?
A. It is impossible
B. Increasing analog-to-digital conversion resolution
C. Using a more efficient digital code ✓
D. Using forward error correction
E8C11
What is the relationship between symbol rate and baud?
A. They are the same ✓
B. Baud is twice the symbol rate
C. Baud rate is half the symbol rate
D. The relationship depends on the specific code used
E8C12
What factors affect the bandwidth of a transmitted CW signal?
A. IF bandwidth and Q
B. Modulation index and output power
C. Keying speed and shape factor (rise and fall time) ✓
D. All these choices are correct
E8C13
What is described by the constellation diagram of a QAM or QPSK signal?
A. How many carriers may be present at the same time
B. The possible phase and amplitude states for each symbol ✓
C. Frequency response of the signal stream
D. The number of bits used for error correction in the protocol
E8C14
What type of addresses do nodes have in a mesh network?
A. Email
B. Trust server
C. Internet Protocol (IP) ✓
D. Talk group
E8C15
What technique do individual nodes use to form a mesh network?
A. Forward error correction and Viterbi codes
B. Acting as store-and-forward digipeaters
C. Discovery and link establishment protocols ✓
D. Custom code plugs for the local trunking systems
E8D01
Why are received spread spectrum signals resistant to interference?
A. Signals not using the spread spectrum algorithm are suppressed in the receiver ✓
B. The high power used by a spread spectrum transmitter keeps its signal from being easily overpowered
C. Built-in error correction codes minimize interference
D. If the receiver detects interference, it will signal the transmitter to change frequencies
E8D02
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
E8D03
Which describes spread spectrum frequency hopping?
A. If interference is detected by the receiver, it will signal the transmitter to change frequencies
B. RF signals are clipped to generate a wide band of harmonics which provides redundancy to correct errors
C. A binary bit stream is used to shift the phase of an RF carrier very rapidly in a pseudorandom sequence
D. Rapidly varying the frequency of a transmitted signal according to a pseudorandom sequence ✓
E8D04
What is the primary effect of extremely short rise or fall time on a CW signal?
A. More difficult to copy
B. The generation of RF harmonics
C. The generation of key clicks ✓
D. More difficult to tune
E8D05
What is the most common method of reducing key clicks?
A. Increase keying waveform rise and fall times ✓
B. Insert low-pass filters at the transmitter output
C. Reduce keying waveform rise and fall times
D. Insert high-pass filters at the transmitter output
E8D06
What is the advantage of including parity bits in ASCII characters?
A. Faster transmission rate
B. Signal-to-noise ratio is improved
C. A larger character set is available
D. Some types of errors can be detected ✓
E8D07
What is a common cause of overmodulation of AFSK signals?
A. Excessive numbers of retries
B. Excessive frequency deviation
C. Bit errors in the modem
D. Excessive transmit audio levels ✓
E8D08
What parameter evaluates distortion of an AFSK signal caused by excessive input audio levels?
A. Signal-to-noise ratio
B. Baud error rate
C. Repeat Request Rate (RRR)
D. Intermodulation Distortion (IMD) ✓
E8D09
What is considered an acceptable maximum IMD level for an idling PSK signal?
A. +5 dB
B. +10 dB
C. +15 dB
D. -30 dB ✓
E8D10
What are some of the differences between the Baudot digital code and ASCII?
A. Baudot uses 4 data bits per character, ASCII uses 7 or 8; Baudot uses 1 character as a letters/figures shift code, ASCII has no letters/figures code
B. Baudot uses 5 data bits per character, ASCII uses 7 or 8; Baudot uses 2 characters as letters/figures shift codes, ASCII has no letters/figures shift code ✓
C. Baudot uses 6 data bits per character, ASCII uses 7 or 8; Baudot has no letters/figures shift code, ASCII uses 2 letters/figures shift codes
D. Baudot uses 7 data bits per character, ASCII uses 8; Baudot has no letters/figures shift code, ASCII uses 2 letters/figures shift codes
E8D11
What is one advantage of using 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 uppercase and lowercase text ✓
D. It uses one character as a shift code to send numeric and special characters