192. What would be the frequency of a range ring marker oscillator generating range rings at intervals of 0.25 nautical miles?

The frequency of a range ring marker oscillator generating range rings at 0.25 nautical mile intervals is calculated from the two-way travel time corresponding to that distance. A nautical mile equates to approximately 12.36 microseconds of two-way travel time, so 0.25 nautical miles corresponds to roughly 3.09 microseconds. The oscillator frequency is the inverse of this time, resulting in a frequency of approximately 322 kHz.