E4C01:

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

  1. It limits the receiver's ability to receive strong signals
  2. It reduces receiver sensitivity
  3. It decreases receiver third-order intermodulation distortion dynamic range
  4. It can cause strong signals on nearby frequencies to interfere with reception of weak signals

E4C02:

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

  1. A front-end filter or pre-selector
  2. A narrow IF filter
  3. A notch filter
  4. A properly adjusted product detector

E4C03:

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

  1. Desensitization
  2. Cross-modulation interference
  3. Capture effect
  4. Frequency discrimination

E4C04:

How is the noise figure of a receiver defined?

  1. The ratio of atmospheric noise to phase noise
  2. The ratio of the noise bandwidth in Hertz to the theoretical bandwidth of a resistive network
  3. The ratio of thermal noise to atmospheric noise
  4. The ratio in dB of the noise generated by the receiver to the theoretical minimum noise

E4C05:

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

  1. The minimum detectable signal as a function of receive frequency
  2. The theoretical noise at the input of a perfect receiver at room temperature
  3. The noise figure of a 1 Hz bandwidth receiver
  4. The galactic noise contribution to minimum detectable signal

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?

  1. -174 dBm
  2. -164 dBm
  3. -155 dBm
  4. -148 dBm

E4C07:

What does the MDS of a receiver represent?

  1. The meter display sensitivity
  2. The minimum discernible signal
  3. The multiplex distortion stability
  4. The maximum detectable spectrum

E4C08:

An SDR receiver is overloaded when input signals exceed what level?

  1. One-half the maximum sample rate
  2. One-half the maximum sampling buffer size
  3. The maximum count value of the analog-to-digital converter
  4. The reference voltage of the analog-to-digital converter

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?

  1. Fewer components in the receiver
  2. Reduced drift
  3. Easier for front-end circuitry to eliminate image responses
  4. Improved receiver noise figure

E4C10:

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

  1. 100 Hz
  2. 300 Hz
  3. 6000 Hz
  4. 2400 Hz

E4C11:

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

  1. 1 kHz
  2. 2.4 kHz
  3. 4.2 kHz
  4. 4.8 kHz

E4C12:

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

  1. Output-offset overshoot
  2. Filter ringing
  3. Thermal-noise distortion
  4. Undesired signals may be heard

E4C13:

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

  1. It improves sensitivity by reducing front end noise
  2. It improves intelligibility by using low Q circuitry to reduce ringing
  3. It improves dynamic range by attenuating strong signals near the receive frequency
  4. All of these choices are correct

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?

  1. 13.845 MHz
  2. 14.755 MHz
  3. 14.445 MHz
  4. 15.210 MHz

E4C15:

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

  1. Detector noise
  2. Induction motor noise
  3. Receiver front-end noise
  4. Atmospheric noise

E4C16:

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

  1. Distortion
  2. Overload
  3. Loss of sensitivity
  4. Excess output level

E4C17:

Which of the following has the largest effect on an SDR receiver's linearity?

  1. CPU register width in bits
  2. Anti-aliasing input filter bandwidth
  3. RAM speed used for data storage
  4. Analog-to-digital converter sample width in bits