Subelement K: K – Aircraft— Topic 69: VHF Omnidirectional Range (VOR)
Question 3-69K5
Element 3 (GROL)The amplitude modulated variable phase signal and the frequency modulated reference phase signal of a Very-high-frequency Omnidirectional Range (VOR) station used for aircraft navigation are synchronized so that both signals are in phase with each other at ____________ of the VOR station.
Explanation
A Very-high-frequency Omnidirectional Range (VOR) station determines an aircraft's bearing by comparing the phase of two 30 Hz signals: a reference phase signal (omnidirectional, FM subcarrier) and a variable phase signal (rotating, AM).
These two signals are intentionally synchronized to be in phase with each other precisely along the **0-degree (or 360-degree) radial** emanating from the VOR station. Crucially, VOR navigation systems operate using **magnetic bearings**, not true bearings. Therefore, the synchronization point is at 0 degrees North (or 360 degrees North) relative to magnetic north.
* **Option B** correctly identifies "360 degrees North" and specifies "magnetic bearing position," aligning with how VOR radials are defined and synchronized.
* **Option A, C, and D** are incorrect because they either refer to 180 degrees South (the opposite radial), use "true bearing" instead of "magnetic bearing," or both. VORs are fundamentally oriented to magnetic north.
Related Questions
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