Lesson 39 Practice Problems#
An airplane is flying overhead with an approach angle of 60°. If a RADAR transmits a signal at 300 MHz and it returns at 300.000125 MHz, how fast is the airplane traveling?
A RADAR with a PRI of 200 \(\mu\)s is trying to detect an aircraft that is 50 km away. The RADAR receives a return from the approaching aircraft, but the RADAR operator does not realize the power level is too low to be a viable signal. How far away will the RADAR think the aircraft is?
An integral part of an instrument flight rules navigation system is its RADAR altimeter. Adam Aircraft is designing a new jet. The RADAR engineer decided to use a pulse width of 1 \(\mu\)s. Would you feel safe flying in this airplane? Why or why not?
The RADAR for a surface-to-air missile (SAM) system uses a PRF of 6 kHz and a pulse width of 300 ns.
a. What is the PRI?
b. If you are 28 km from the SAM site, does it know where you are (without additional processing)?
c. If you are ingressing as a two-ship with 10 m spacing, will the SAM be able to tell there are two of you?
You need to design a RADAR system that can distinguish between objects with a separation of 25 m. You also need to be able to unambiguously determine the position of an object out to 75 km.
a. What pulse width will you use?
b. What PRF will you use?
A RADAR ground station wants to set its maximum unambiguous range to 20 km.
a. What PRF should they use for the RADAR?
b. How high off the ground does the antenna need to be?
A UAS is moving directly away from you (approach angle = 0°) at a speed of 90 m/s. If your RADAR uses a frequency of 2.4 GHz, at what frequency will the RADAR signal return?
A RADAR’s operating frequency is 4 GHz. An enemy aircraft is approaching at 800 km/h.
a. What is the Doppler shift of the signal received by the RADAR if the aircraft is coming directly at the RADAR?
b. Suppose the aircraft turns around and heads in the opposite direction. What is the new Doppler shift?
An unidentified aircraft is traveling toward you with an approach angle of 40°. If your RADAR transmits at 1.2 GHz and receives a 1.2000008465 GHz signal in return, how fast is the aircraft traveling?
An F-16 with a RADAR cross section of \(5\ m^2\) is flying at 1200 ft AGL, approaching a RADAR station. Its RADAR Warning Receiver (RWR) has a gain of 3 and requires 3 \(\mu\)W to detect a signal. The RADAR station is transmitting from 50 ft AGL at 200 MHz with a power of 4 kW. The antenna has a gain of 250 and requires 14 fW to identify a target. The RADAR has a PRF of 2 kHz and a pulse width of 200 ns.
Find the following:
a. Maximum detection range of the RADAR
b. Line-of-sight (LOS) range
c. Maximum unambiguous range
d. Maximum detection range of the F-16’s RWR
e. \(\Delta R\)