E4C-2012: Receiver performance characteristics, phase noise, capture effect, noise floor, image rejection, MDS, signal-to-noise-ratio; selectivity
E4C01-2012:
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
E4C02-2012:
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
E4C03-2012:
What is the term for the blocking of one FM phone signal by another, stronger FM phone signal?
Capture effect
Desensitization
Cross-modulation interference
Frequency discrimination
E4C04-2012:
What is the definition of the noise figure of a receiver?
The ratio in dB of the noise generated by the receiver compared to the theoretical minimum noise
The ratio of atmospheric noise to phase noise
The noise bandwidth in Hertz compared to the theoretical bandwidth of a resistive network
The ratio of thermal noise to atmospheric noise
E4C05-2012:
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
E4C06-2012:
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
E4C07-2012:
What does the MDS of a receiver represent?
The minimum discernible signal
The meter display sensitivity
The multiplex distortion stability
The maximum detectable spectrum
E4C08-2012:
How might lowering the noise figure affect receiver performance?
It would improve weak signal sensitivity
It would reduce the signal to noise ratio
It would reduce bandwidth
It would increase bandwidth
E4C09-2012:
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
E4C10-2012:
Which of the following is a desirable amount of selectivity for an amateur RTTY HF receiver?
300 Hz
100 Hz
6000 Hz
2400 Hz
E4C11-2012:
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
E4C12-2012:
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
E4C13-2012:
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
E4C14-2012:
On which of the following frequencies might a signal be transmitting which is generating a spurious image 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
E4C15-2012:
What is the primary source of noise that can be heard from an HF receiver with an antenna connected?
Atmospheric noise
Detector noise
Induction motor noise
Receiver front-end noise
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