Key Topic 13: Modulation

Question 1

8-13B1: In a solid-state RADAR modulator, the duration of the transmitted pulse is determined by:

A. The thyratron.
B. The magnetron voltage.
C. The pulse forming network.
D. The trigger pulse.

Answer 1

C. The pulse forming network.

Question 2

8-13B2: The modulation frequency of most RADAR systems is between:

A. 60 and 500 Hz.
B. 3000 and 6000 Hz.
C. 1500 and 7500 Hz.
D. 1000 and 3000 Hz.

Answer 2

A. 60 and 500 Hz.

Question 3

8-13B3: A shipboard RADAR uses a PFN driving a magnetron cathode through a step-up transmformer. This results in which type of modulation?

A. Frequency modulation.
B. Amplitude modulation.
C. Continuous Wave (CW) modulation.
D. Pulse modulation.

Answer 3

D. Pulse modulation.

Question 4

8-13B4: In a pulse modulated magnetron what device determines the shape and width of the pulse?

A. Pulse Forming Network.
B. Thyratron.
C. LC parallel circuit.
D. Dimensions of the magnetron cavity.

Answer 4

A. Pulse Forming Network.

Question 5

8-13B5: What device(s) may act as the modulator of a RADAR system?

A. Magnetron.
B. Klystron.
C. Video amplifier.
D. Thyratron or a silicon-controlled rectifier (SCR).

Answer 5

D. Thyratron or a silicon-controlled rectifier (SCR).

Question 6

8-13B6: The purpose of a modulator in the transmitter section of a RADAR is to:

A. Improve bearing resolution.
B. Provide the correct waveform to the transmitter.
C. Prevent sea return.
D. Control magnetron power output.

Answer 6

B. Provide the correct waveform to the transmitter.