Custom Kalman Filter settings

Parameter	Description
VTC	Vertical Time Constant	Time constant over which the vertical velocity vector is likely to change (seconds)
HTC	Horizontal Time Constant	Time constant over which the horizontal velocity vector is likely to change (seconds)
VSS	Vertical Steady State	Standard deviation of vertical velocity vector (meters/second, 1-sigma)
HSS	Horizontal Steady State	Standard deviation of horizontal velocity vector (meters/second, 1-sigma)

These parameters affect how the RB-Pro APNT internal Kalman Filter estimates dynamic position in the absence of bursts or aiding inputs.

The time constant represents the PRESUMED rate at which the velocity vector is liable to change.

The steady state is the PRESUMED standard deviation of the velocity PDF (probability distribution function), in the axis or plane of interest.

A highly-dynamic, fast-moving object would necessitate a large steady state and a small time constant.

A slow-moving object that changes direction and speed only rarely would necessitate a small steady state and a large time constant.

For reference the Kalman Filter profiles are as follows:

Pre-set	VTC [s]	HTC [s]	VSS [m/s]	HSS [m/s]
Maritime (Product produced before 28th Nov 2025)	5	300	0.1	15
Maritime (Product produced after 28th Nov 2025)	5	60	0.1	15
Walking	5	300	0.1	5
Driving (Product produced before 28th Nov 2025)	30	10	0.1	10
Driving (Product produced after 28th Nov 2025)	5	30	0.5	10

Note: The pre-set values are factory set and can only be changed by loading a new kalman.cfg file (Contact tech support for details). Pre-set values are not impacted by firmware updates.

The table below shows alternative profiles for other tracking scenarios. Can be set using the 'custom' feature.

Profile	VTC [s]	HTC [s]	VSS [m/s]	HSS [m/s]
Maritime slow moving	5	60	0.1	15
City driving	5	30	0.5	10
Highway driving	5	300	0.5	15
Fixed Wing Aircraft (small, slow)	30	300	5	60
Fixed Wing Aircraft (large, fast)	30	300	10	100
Rotary Aircraft	30	300	5	60
Walking speeds	5	60	0.5	2