E4C: Receiver performance characteristics, part 1: phase noise, capture effect, noise floor, image rejection, MDS, signal-to-noise-ratio; selectivity
E4C01:
What is the 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 ability to receive strong signals
It reduces the receiver sensitivity
It decreases the receiver third-order intermodulation distortion dynamic range
E4C02:
Which of the following is the result of the capture effect in an FM receiver?
The strongest signal received is the only demodulated signal
All signals on a frequency are demodulated
None of the signals could be heard
The weakest signal received is the only demodulated signal
E4C03:
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:
What is meant by the noise floor of a receiver?
The equivalent input noise power when the antenna is replaced with a matched dummy load
The minimum level of noise at the audio output when the RF gain is turned all the way down
The equivalent phase noise power generated by the local oscillator
The minimum level of noise that will overload the RF amplifier stage
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
E4C06:
The thermal noise value of a receiver is -174 dBm/Hz. What is the theoretically best minimum detectable signal for a 400 Hz bandwidth receiver?
-148 dBm
174 dBm
-164 dBm
-155 dBm
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
E4C08:
How might lowering the noise figure affect receiver performance?
It would increase signal to noise ratio
It would reduce the signal to noise ratio
It would reduce bandwidth
It would increase bandwidth
E4C09:
Which of the following is most likely to be the limiting condition for sensitivity in a modern communications receiver operating at 14 MHz?
Atmospheric noise
The noise figure of the RF amplifier
Mixer noise
Conversion noise
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
E4C11:
Which of the following is a desirable amount of selectivity for an amateur single-sideband phone receiver?
2.4 kHz
1 kHz
4.2 kHz
4.8 kHz
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
E4C13:
How does a narrow band roofing filter affect receiver performance?
It improves dynamic range by keeping strong signals near the receive frequency out of the IF stages
It improves sensitivity by reducing front end noise
It improves intelligibility by using low Q circuitry to reduce ringing
All of these choice are correct
E4C14:
Which of these choices is a desirable amount of selectivity for an amateur VHF FM receiver?
15 kHz
1 kHz
2.4 kHz
4.2 kHz
E4C15:
What is the primary source of noise that can be heard from an HF-band receiver with an antenna connected?
Atmospheric noise
Detector noise
Induction motor noise
Receiver front-end noise
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