Heading Sources

There are several different heading sources available for Boreas. The heading sources can be configured using the Filter Options page in the web UI (see Using the Web User Interface) or in the Manager application (see Using Boreas Manager). It is possible to use multiple heading sources and this can provide performance benefits.

North Seeking Gyrocompass Heading

The Boreas provides north-seeking gyrocompassing which determines heading using the earth's rotation without GNSS or other aiding sources. Initialization requires an initial approximate latitude, within 50 km range, then increases accuracy as the earth spins. Rotations during initialization improves accuracy, as is typically experienced during navigation.

Dual Antenna Heading

For devices that support dual GNSS antenna input, this is the heading source that provides the most accurate heading while GNSS is available. Dual antenna heading only works when a good GNSS fix is available to both antennas. It requires a clear view of the sky with minimal nearby sources of interference or multipath. The greater the antenna separation, the higher the accuracy (see Navigation Specifications). A minimum antenna separation of 0.5 metres is required.

Boreas will operate with a single primary antenna connected, but this will prevent dual-antenna heading being used, although velocity heading will still be possible.

Velocity Heading

For devices that support either single or dual GNSS input, velocity heading works by deriving heading from the direction of velocity and acceleration. Velocity heading works well with cars, fixed wing aircraft and other vehicles that don't move sideways. Velocity heading cannot work for helicopters and other vehicles where the vehicle is pointed somewhere other than the direction of travel. Velocity heading requires a horizontal speed of over 1.15 m/s with a GNSS fix. Velocity heading is disabled by default.

External Heading

This can be used if there is some other way to derive heading that is external to Boreas. The heading must be supplied to Boreas using the External Heading Packet or an NMEA message, see NMEA Input.