Setting up the SPSx61 GPS receivers to provide heading

The SPSx61 receiver is always configured to provide precise GPS Heading when both GPS antennas are connected and have a clear view of the sky.

Even if the receiver is not connected to a correction stream and the position mode is Autonomous it will still provide the same high-precision GPS Heading.

The Heading output of the SPSx61 is relative to True North.

The following figure shows an installation setup for the SPSx61 receiver for position and heading:

Installing the receiver

Select a location at which all of the following conditions are met:

  • the receiver is not exposed to temperature extremes

  • the receiver is not exposed to moisture extremes (such as rain, snow, water blasters, or wash systems)

  • the receiver is protected from mechanical damage

  • you can connect and disconnect cables without placing undue stress on them

Mounting the antennas

You must install each antenna at the correct location. Poor or incorrect placement can influence accuracy and reliability.

Ideally, mount the two antennas as far apart as possible and at about the same height on the structure. Mount the antennas fore and aft along the vessel centerline or on a line that is at a known orientation to the centerline. For best results, rotate each antenna so that all antennas in the array point in the same direction. Always mount an antenna at a location that ensures a good view of the sky.

Follow these guidelines to select the antenna location:

  • Choose an area with a clear view of the sky. The antenna must be above any metallic objects.

  • Do not mount the antenna close to stays, electrical cables, metal masts, or other antennas.

  • Do not mount the antenna near a transmitting antenna, a radar array, or near satellite communication equipment.

  • Avoid areas with high vibration, excessive heat, electrical interference, and strong magnetic fields.

Use a 5/8"×11" stainless steel bolt to mount each of the antennas. There is a threaded bolt hole in the base of the antenna.

The GNSS antenna and its cabling should be installed in accordance with all national and local electrical codes, regulations, and practices. The antenna and cabling should be installed where they will not become energized as a result of falling nearby power lines, nor be mounted where they are subjected to over-voltage transients, particularly lightning. Such installations require additional protective means that are detailed in national and local electrical codes.

Interfacing using the NMEA protocol

The default factory settings enable the NMEA HDT and GGA output on Serial 3 of the SPSx61 receiver. You can set up an alternative configuration from the front panel of the receiver by pressing until the NMEA screen appears and then selecting the required NMEA output message for either Serial 2 (Modem) or Serial 3.

Heading output

The heading output from an SPSx61 receiver that is in Rover or Moving Base mode is the True North Azimuth from the Vector antenna to the Position antenna. Heading output information is available in the following places: