What is a satellite Compass?

A satellite compass uses signals from two or three GPS antennas to compute the heading and other characteristics about a vessel at any point in time.  It is important that the antennas are precisely spaced and located on a rigid platform because the differences between the received signals is analysed to determine the course and other parameters.  The great advantage is that in terms of cost it is cheaper than a Gyro compass whilst providing comparable performance.

In recent years development has concentrated on both improving GPS receivers and the addition of electronic Gyros and tilt sensors to improve performance and provide heading information when GPS signals are weak or not present.  Developments like this are ensuring that the Satellite Compass performs better and more reliably.  The latest generation of Satellite Compasses provide multiple programmable outputs and information about not only the course and position but vertical movement (heaving) as well.

In the True Heading Vector Carbon Satellite Compass, once four or more satellites are tracked it can compute the position to an accuracy of better than 1 mtr for 95% of the time.  Information derived from the two internal GPS receivers allows it to calculate the heading.  How it does this is based on some complex mathmatics and physically keeping the relative position of the two antennas rigidly fixed, which is why it has a cast aluminium base.

The inclusion of a gyro sensor and tilt sensors (accelerometers) in the same enclosure ensure that satellite startup and reacquisition times are improved and the gyro allows a heading to be provided for short periods (minutes) when the GPS signal is lost.

This particular satellite compass has two NMEA0183 outputs that are programmable in terms of content and speed.  It is also supplied with an optional NMEA 2000 output.

Installing a Satellite Compass

When installing a satellite Compass there are four requirements to consider.

The first requirement is that because it is a GPS based system a clear view of the sky is required.  When satellites are masked by superstructure, system performance can be impaired.

The second requirement is to ensure that the Satellite Compass is positioned clear of any other transmitting antennas on the vessel.  The manufacturer will specify what the practical limits are.

The third requirement, particularly on larger vessels, is that the position of the Satellite Compass on the vessel should be accurately known.  This information is important when programming systems such as AIS.

The fourth requirement, is that the mounting position should be rigid and stable to ensure a stable platform for the satellite compass.

If you are considering installing a satellite compass then contact us to discuss further.   We can provide a lot of information when you are ready to go the Satellite Compass route and you may be pleased to find the price is good as well.