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Extra Class Exam Question Pool

effective 7/01/2016 thru 6/29/2020

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2016-E4C: Receiver performance characteristics, phase noise, noise floor, image rejection, MDS, signal-to-noise-ratio; selectivity; effects of SDR receiver non-linearity

2016-E4C01: What is an effect of excessive phase noise in the local oscillator section of a receiver?

It can cause strong signals on nearby frequencies to interfere with reception of weak signals

It limits the receiver's ability to receive strong signals

It reduces receiver sensitivity

It decreases receiver third-order intermodulation distortion dynamic range

2016-E4C02: Which of the following portions of a receiver can be effective in eliminating image signal interference?

A front-end filter or pre-selector

A narrow IF filter

A notch filter

A properly adjusted product detector

2016-E4C03: What is the term for the blocking of one FM phone signal by another, stronger FM phone signal?

Capture effect


Cross-modulation interference

Frequency discrimination

2016-E4C04: How is the noise figure of a receiver defined?

The ratio in dB of the noise generated by the receiver to the theoretical minimum noise

The ratio of atmospheric noise to phase noise

The ratio of the noise bandwidth in Hertz to the theoretical bandwidth of a resistive network

The ratio of thermal noise to atmospheric noise

2016-E4C05: What does a value of -174 dBm/Hz represent with regard to the noise floor of a receiver?

The theoretical noise at the input of a perfect receiver at room temperature

The minimum detectable signal as a function of receive frequency

The noise figure of a 1 Hz bandwidth receiver

The galactic noise contribution to minimum detectable signal

2016-E4C06: A CW receiver with the AGC off has an equivalent input noise power density of -174 dBm/Hz. What would be the level of an unmodulated carrier input to this receiver that would yield an audio output SNR of 0 dB in a 400 Hz noise bandwidth?

-148 dBm

-174 dBm

-164 dBm

-155 dBm

2016-E4C07: What does the MDS of a receiver represent?

The minimum discernible signal

The meter display sensitivity

The multiplex distortion stability

The maximum detectable spectrum

2016-E4C08: An SDR receiver is overloaded when input signals exceed what level?

The maximum count value of the analog-to-digital converter

One-half the maximum sample rate

One-half the maximum sampling buffer size

The reference voltage of the analog-to-digital converter

2016-E4C09: Which of the following choices is a good reason for selecting a high frequency for the design of the IF in a conventional HF or VHF communications receiver?

Easier for front-end circuitry to eliminate image responses

Fewer components in the receiver

Reduced drift

Improved receiver noise figure

2016-E4C10: Which of the following is a desirable amount of selectivity for an amateur RTTY HF receiver?

300 Hz

100 Hz

6000 Hz

2400 Hz

2016-E4C11: Which of the following is a desirable amount of selectivity for an amateur SSB phone receiver?

2.4 kHz

1 kHz

4.2 kHz

4.8 kHz

2016-E4C12: What is an undesirable effect of using too wide a filter bandwidth in the IF section of a receiver?

Undesired signals may be heard

Output-offset overshoot

Filter ringing

Thermal-noise distortion

2016-E4C13: How does a narrow-band roofing filter affect receiver performance?

It improves dynamic range by attenuating strong signals near the receive frequency

It improves sensitivity by reducing front end noise

It improves intelligibility by using low Q circuitry to reduce ringing

All of these choices are correct

2016-E4C14: What transmit frequency might generate an image response signal in a receiver tuned to 14.300 MHz and which uses a 455 kHz IF frequency?

15.210 MHz

13.845 MHz

14.755 MHz

14.445 MHz

2016-E4C15: What is usually the primary source of noise that is heard from an HF receiver with an antenna connected?

Atmospheric noise

Detector noise

Induction motor noise

Receiver front-end noise

2016-E4C16: Which of the following is caused by missing codes in an SDR receiver's analog-to-digital converter?



Loss of sensitivity

Excess output level

2016-E4C17: Which of the following has the largest effect on an SDR receiver's linearity?

Analog-to-digital converter sample width in bits

CPU register width in bits

Anti-aliasing input filter bandwidth

RAM speed used for data storage

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2016-E4B: Measurement technique and limitations: instrument accuracy and performance limitations; probes; techniques to minimize errors; measurement of "Q"; instrument calibration; S parameters; vector network analyzers
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2016-E4D: Receiver performance characteristics: blocking dynamic range; intermodulation and cross-modulation interference; 3rd order intercept; desensitization; preselector
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