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Due to vibration the accelerations (both linear and angular) are noisy. In particular, angular acceleration is
normally filtered when it is used. The RT can filter the acceleration outputs using a second order low-pass filter.
The characteristics of the filter can be set and viewed in the Acceleration Filters tab in the Advanced Tools
section of NAVconfig.
Designing the right filter is always a compromise between the noise reduction and the filter delay. To help
choose the filter, the software will compute the maximum delay over the 0 to 5 Hz interval and the Noise
Reduction Factor over the full bandwidth. The Noise Reduction Factor is the ratio of the filtered noise compared
to the unfiltered noise assuming the vibration is white (i.e. same amplitude across the frequency spectrum). A
graph showing the delay with respect to frequency can also be plotted. The delay is the additional delay of the
filter and not the total delay of the acceleration output. The RT has other delays, like calculation delay, too.
Figure 37: NAVconfig acceleration filters tab in the advanced tools section
Wheel Speed Input
The RT can be factory configured to include a wheel speed input. This reduces the drift in outputs when GNSS
is not available. It is essential to use the Lateral and Vertical No-slip slip features at the same time as wheel
speed corrections.
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