If the GPS-INS difference is greater than the threshold, what happens?

Master the Navigation, Seamanship, and Shiphandling (NSS) – Officer of the Deck (OOD) Phase 2 Exam with engaging flashcards and multiple choice questions, complete with hints and explanations. Prepare comprehensively for your test!

Multiple Choice

If the GPS-INS difference is greater than the threshold, what happens?

Explanation:
When the GPS–INS difference is larger than the threshold, it means the GPS observation is unreliable for that moment. The system marks the GPS update as out of gate and rejects that position update, continuing to rely on the inertial navigation solution instead. This integrity check prevents a large, erroneous GPS correction from corrupting the overall navigation solution, especially in cases of GPS glitches, multipath, or temporary outages. Once a future GPS update falls within the acceptable range, updates resume; there’s no automatic recalibration of the INS or a switch to celestial navigation triggered by this alone.

When the GPS–INS difference is larger than the threshold, it means the GPS observation is unreliable for that moment. The system marks the GPS update as out of gate and rejects that position update, continuing to rely on the inertial navigation solution instead. This integrity check prevents a large, erroneous GPS correction from corrupting the overall navigation solution, especially in cases of GPS glitches, multipath, or temporary outages. Once a future GPS update falls within the acceptable range, updates resume; there’s no automatic recalibration of the INS or a switch to celestial navigation triggered by this alone.

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