Integrated Navigation Practice Test 2026 – Complete Exam Prep

In a tightly coupled GNSS/INS system, all available GNSS measurements are used together because they provide complementary information that constrains the navigation state more effectively. Pseudorange gives a coarse distance to each satellite and helps establish the position and receiver clock bias. Doppler measures the rate of change of range, which translates into velocity information and helps track motion consistently with the INS. Carrier phase offers very high precision distance information, but it comes with integer cycle ambiguities that must be resolved; when combined with Doppler and pseudorange, these ambiguities can be estimated within the same filter rather than treated as separate, isolated data.

Using all three measurements allows the estimator to solve for position, velocity, receiver clock error, and carrier-phase ambiguities simultaneously, yielding robust accuracy even when some satellites are weak or temporarily unavailable. Relying on just one type would either limit observability (pseudorange alone), lose velocity information (carrier phase alone), or lack the long-term precision and ambiguity resolution (Doppler alone).