Question 3-90O2

RADAR determines range by measuring the elapsed time between transmitting a pulse and receiving its echo. The pulse travels at the speed of light to the object and back, meaning the total distance covered is twice the actual range. To calculate range in nautical miles (nm), we need to know how long it takes for a pulse to travel a round trip distance equivalent to 1 nautical mile of range. 1 nautical mile = 1852 meters. The speed of light (c) is approximately 3 x 10^8 meters per second. Time for a one-way trip of 1 nm = 1852 m / (3 x 10^8 m/s) = 6.173 x 10^-6 seconds = 6.173 microseconds (μs). Since RADAR measures the round-trip time, the elapsed time for a target at 1 nm range is double this value: Round-trip time for 1 nm range = 2 * 6.173 μs = 12.346 μs. Therefore, dividing the total elapsed time (in μs) by 12.346 μs gives the range directly in nautical miles. The other options are incorrect values that do not account for the round trip distance and conversion to nautical miles from the speed of light.