What is the purpose of a high-rate filter in integrated navigation?

• A. To increase computational load without benefit.
• B. To provide state estimates at a high update rate (matching IMU) and reduce drift by frequent prediction and alignment with GNSS when available.
• C. To filter out high-frequency noise only from optics.
• D. To convert GNSS time to GPS time.

Answer: (B)

High-rate filtering keeps the state estimate updated as fast as the IMU data arrives. The IMU provides measurements at a very high cadence, and the filter uses these to continuously propagate (predict) position, velocity, attitude, and sensor biases. GNSS updates, when available, are then used to correct those errors and drift, pulling the estimate back toward the true trajectory. This combination lets you have accurate, timely state estimates between GNSS updates and minimizes drift over time.

This isn’t about merely increasing computation for no gain, filtering optical noise, or converting GNSS time to GPS time. It’s about delivering high-rate, reliable state estimates by frequent prediction with the IMU and periodic correction with GNSS.