Signals and Emissions
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General Class Exam Question Pool

effective 7/01/2011 thru 6/30/2015

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Topic G8: Signals and Emissions


G8A-2011: Carriers and modulation: AM; FM; single and double sideband; modulation envelope; overmodulation

G8A01-2011: What is the name of the process that changes the envelope of an RF wave to carry information?

Amplitude modulation

Phase modulation

Frequency modulation

Spread spectrum modulation



G8A02-2011: What is the name of the process that changes the phase angle of an RF wave to convey information?

Phase modulation

Phase convolution

Angle convolution

Radian inversion



G8A03-2011: What is the name of the process which changes the frequency of an RF wave to convey information?

Frequency modulation

Frequency convolution

Frequency transformation

Frequency conversion



G8A04-2011: What emission is produced by a reactance modulator connected to an RF power amplifier?

Phase modulation

Multiplex modulation

Amplitude modulation

Pulse modulation



G8A05-2011: What type of modulation varies the instantaneous power level of the RF signal?

Amplitude modulation

Frequency shift keying

Pulse position modulation

Frequency modulation



G8A06-2011: What is one advantage of carrier suppression in a single-sideband phone transmission?

The available transmitter power can be used more effectively

Audio fidelity is improved

Greater modulation percentage is obtainable with lower distortion

Simpler receiving equipment can be used



G8A07-2011: Which of the following phone emissions uses the narrowest frequency bandwidth?

Single sideband

Double sideband

Phase modulation

Frequency modulation



G8A08-2011: Which of the following is an effect of over-modulation?

Excessive bandwidth

Insufficient audio

Insufficient bandwidth

Frequency drift



G8A09-2011: What control is typically adjusted for proper ALC setting on an amateur single sideband transceiver?

Transmit audio or microphone gain

The RF clipping level

Antenna inductance or capacitance

Attenuator level



G8A10-2011: What is meant by flat-topping of a single-sideband phone transmission?

Signal distortion caused by excessive drive

Signal distortion caused by insufficient collector current

The transmitter's automatic level control is properly adjusted

The transmitter's carrier is properly suppressed



G8A11-2011: What happens to the RF carrier signal when a modulating audio signal is applied to an FM transmitter?

The carrier frequency changes proportionally to the instantaneous amplitude of the modulating signal

The carrier frequency changes proportionally to the amplitude and frequency of the modulating signal

The carrier amplitude changes proportionally to the instantaneous frequency of the modulating signal

The carrier phase changes proportionally to the instantaneous amplitude of the modulating signal



G8A12-2011: What signal(s) would be found at the output of a properly adjusted balanced modulator?

Both upper and lower sidebands

Either upper or lower sideband, but not both

Both upper and lower sidebands and the carrier

The modulating signal and the unmodulated carrier






G8B-2011: Frequency mixing; multiplication; HF data communications; bandwidths of various modes; deviation

G8B01-2011: What receiver stage combines a 14.250 MHz input signal with a 13.795 MHz oscillator signal to produce a 455 kHz intermediate frequency (IF) signal?

Mixer

BFO

VFO

Discriminator



G8B02-2011: If a receiver mixes a 13.800 MHz VFO with a 14.255 MHz received signal to produce a 455 kHz intermediate frequency (IF) signal, what type of interference will a 13.345 MHz signal produce in the receiver?

Image response

Quadrature noise

Mixer interference

Intermediate interference



G8B03-2011: What is another term for the mixing of two RF signals?

Heterodyning

Synthesizing

Cancellation

Phase inverting



G8B04-2011: What is the name of the stage in a VHF FM transmitter that generates a harmonic of a lower frequency signal to reach the desired operating frequency?

Multiplier

Mixer

Reactance modulator

Pre-emphasis network



G8B05-2011: Why isn't frequency modulated (FM) phone used below 29.5 MHz?

The wide bandwidth is prohibited by FCC rules

The transmitter efficiency for this mode is low

Harmonics could not be attenuated to practical levels

The frequency stability would not be adequate



G8B06-2011: What is the total bandwidth of an FM-phone transmission having a 5 kHz deviation and a 3 kHz modulating frequency?

16 kHz

3 kHz

5 kHz

8 kHz



G8B07-2011: What is the frequency deviation for a 12.21-MHz reactance-modulated oscillator in a 5-kHz deviation, 146.52-MHz FM-phone transmitter?

416.7 Hz

101.75 Hz

5 kHz

60 kHz



G8B08-2011: Why is it important to know the duty cycle of the data mode you are using when transmitting?

Some modes have high duty cycles which could exceed the transmitter's average power rating.

To aid in tuning your transmitter

To allow time for the other station to break in during a transmission

All of these choices are correct



G8B09-2011: Why is it good to match receiver bandwidth to the bandwidth of the operating mode?

It results in the best signal to noise ratio

It is required by FCC rules

It minimizes power consumption in the receiver

It improves impedance matching of the antenna



G8B10-2011: What does the number 31 represent in PSK31?

The approximate transmitted symbol rate

The version of the PSK protocol

The year in which PSK31 was invented

The number of characters that can be represented by PSK31



G8B11-2011: How does forward error correction allow the receiver to correct errors in received data packets?

By transmitting redundant information with the data

By controlling transmitter output power for optimum signal strength

By using the varicode character set

By using a parity bit with each character



G8B12-2011: What is the relationship between transmitted symbol rate and bandwidth?

Higher symbol rates require higher bandwidth

Symbol rate and bandwidth are not related

Lower symbol rates require higher bandwidth

Bandwidth is constant for data mode signals





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