# Radar and sonar

- What is the main difference between active and passive sonar?

a) Active sonar uses lower frequencies than passive sonar

b) Passive sonar emits no energy while active sonar does

c) Passive sonar has a maximum operating range of 10 to 100 kilometers while active sonar can detect objects at longer ranges

d) Active sonar listens to underwater sounds, while passive sonar transmits sound pulses.

Answer: b) Passive sonar emits no energy while active sonar does.

- 2. What is the main challenge facing radar systems?

a) The ability to accurately determine an object's direction

b) The conflict between the ability to detect objects at a long range and the ability to accurately determine an object's distance

c) The noise level of the radio receiver

d) The difficulty in selecting and generating different pulse shapes and lengths.

Answer: b) The conflict between the ability to detect objects at a long range and the ability to accurately determine an object's distance.

- 3. What is the advantage of using lower frequencies in passive sonar?

a) They propagate through the water with less absorption

b) They allow for better distance determination without reducing the operating range

c) They increase the range without degrading the distance determination

d) They enable the rapid selection and generation of different pulse shapes and lengths.

Answer: a) They propagate through the water with less absorption.

- 4. What is the main advantage of using DSP in radar systems?

a) To increase the operating range of the radar system

b) To accurately determine an object's direction

c) To provide better distance determination without reducing the operating range

d) To decrease the noise level of the radio receiver.

Answer: c) To provide better distance determination without reducing the operating range.