Subelement A: RADAR Principles – 10 Key Topics – 10 Exam Questions – 8 Drawings— Topic 4: Power, Pulse Width, PRR
Question 8-4A3
Element 8 (RADAR)A pulse RADAR transmits a 0.5 microsecond RF pulse with a peak power of 100 kilowatts every 1600 microseconds. This RADAR has:
Explanation
The average power of a pulse RADAR is calculated by multiplying its peak power by its duty cycle.
First, calculate the duty cycle (DC):
DC = Pulse Width (τ) / Pulse Repetition Interval (PRI)
DC = 0.5 microseconds / 1600 microseconds = 0.0003125
Next, calculate the average power:
Average Power = Peak Power * Duty Cycle
Average Power = 100 kilowatts * 0.0003125 = 100,000 watts * 0.0003125 = 31.25 watts.
Therefore, option A is correct.
Let's examine the other options:
B) The Pulse Repetition Frequency (PRF) is 1 / PRI = 1 / (1600 * 10^-6 s) = 625 Hz, not 3,200.
C) The maximum unambiguous range is (speed of light * PRI) / 2 = (300,000 km/s * 0.0016 s) / 2 = 240 km, not 480 km.
D) The duty cycle as a percentage is 0.0003125 * 100% = 0.03125%, not 3.125%.
Related Questions
8-4A1 A pulse RADAR has a pulse repetition frequency (PRF) of 400 Hz, a pulse width of 1 microsecond, and a peak power of 100 kilowatts. The average power of the RADAR transmitter is:8-4A2 A shipboard RADAR transmitter has a pulse repetition frequency (PRF) of 1,000 Hz, a pulse width of 0.5 microseconds, peak power of 150 KW, and a minimum range of 75 meters. Its duty cycle is:8-4A4 If a RADAR transmitter has a pulse repetition frequency (PRF) of 900 Hz, a pulse width of 0.5 microseconds and a peak power of 15 kilowatts, what is its average power output?8-4A5 What is the average power if the RADAR set has a PRF of 1000 Hz, a pulse width of 1 microsecond, and a peak power rating of 100 kilowatts?8-4A6 A search RADAR has a pulse width of 1.0 microsecond, a pulse repetition frequency (PRF) of 900 Hz, and an average power of 18 watts. The unit’s peak power is: