Subelement D: Display & Control Systems - 10 Key Topics – 10 Exam Questions— Topic 32: Fixed Range Markers
Question 8-32D3
Element 8 (RADAR)A gated LC oscillator, operating at 27 kHz, is being used to develop range markers. If each cycle is converted to a range mark, the range between markers will be:
Explanation
The range between markers is determined by the period of the oscillator and the speed of radio waves.
1. **Calculate the period (T) of the oscillator:**
The frequency (f) is 27 kHz (27,000 Hz).
The period T = 1/f = 1 / 27,000 Hz ≈ 0.000037037 seconds, or 37.037 microseconds (µs).
This period represents the time difference between consecutive range markers.
2. **Convert time to range:**
In radar and ranging applications, the signal travels out to a target and back. Therefore, the distance calculated from a time interval is a round-trip distance. A standard constant for range calculations is that a radio wave travels one nautical mile and returns in approximately 12.36 microseconds.
3. **Calculate the range between markers:**
Range = (Period in µs) / (Time per nautical mile round trip)
Range = 37.037 µs / 12.36 µs/NM ≈ 3.00 nautical miles.
Therefore, the range between markers is 3 nautical miles. Options B, C, and D are incorrect as they do not result from this calculation.
Related Questions
8-32D1 Accurate range markers must be developed using very narrow pulses. A circuit that could be used to provide these high-quality pulses for the CRT is a:8-32D2 Range markers are determined by:8-32D4 What would be the frequency of a range ring marker oscillator generating range rings at 10 nautical miles intervals?8-32D5 What is the distance between range markers if the controlling oscillator is operating at 20 kHz?8-32D6 What would be the frequency of a range ring marker oscillator generating range rings at intervals of 0.25 nautical miles?