Key Topic 41: Receiver Theory

Question 1

3-41F1: What is the limiting condition for sensitivity in a communications receiver?

A. The noise floor of the receiver.
B. The power supply output ripple.
C. The two-tone intermodulation distortion.
D. The input impedance to the detector.

Answer 1

A. The noise floor of the receiver.

Question 2

3-41F2: What is the definition of the term “receiver desensitizing”?

A. A burst of noise when the squelch is set too low.
B. A reduction in receiver sensitivity because of a strong signal on a nearby frequency.
C. A burst of noise when the squelch is set too high.
D. A reduction in receiver sensitivity when the AF gain control is turned down.

Answer 2

B. A reduction in receiver sensitivity because of a strong signal on a nearby frequency.

Question 3

3-41F3: What is the term used to refer to a reduction in receiver sensitivity caused by unwanted high-level adjacent channel signals?

A. Desensitizing.
B. Intermodulation distortion.
C. Quieting.
D. Overloading.

Answer 3

A. Desensitizing.

Question 4

3-41F4: What is meant by the term noise figure of a communications receiver?

A. The level of noise entering the receiver from the antenna.
B. The relative strength of a received signal 3 kHz removed from the carrier frequency.
C. The level of noise generated in the front end and succeeding stages of a receiver.
D. The ability of a receiver to reject unwanted signals at frequencies close to the desired one.

Answer 4

C. The level of noise generated in the front end and succeeding stages of a receiver.

Question 5

3-41F5: Which stage of a receiver primarily establishes its noise figure?

A. The audio stage.
B. The RF stage.
C. The IF strip.
D. The local oscillator.

Answer 5

B. The RF stage.

Question 6

3-41F6: What is the term for the ratio between the largest tolerable receiver input signal and the minimum discernible signal?

A. Intermodulation distortion.
B. Noise floor.
C. Noise figure.
D. Dynamic range.

Answer 6

D. Dynamic range.