The alternate method to set the location of the form is to activate NMEA 183 input, if it is available on your PC. The major advantage of using NMEA 183 GPS input is that the radar display will become a moving display when your vessel is underway. In that way the radar display can be an aid to your navigation, although no substitute for proper charts. Here is link to a YouTube video using LightListManager and the radar display as aides to navigation
To activate NMEA input click on the "NMEA Input" Radar Menu Item (Fig. 1). This opens the NMEA Setup dialog box (Fig. 2). Here the COM port and baud rate of the available NMEA data stream are specified. Also if you want to see more data than just that from the GPS, latitude/longitude, Course Over Ground (COG), and Speed Over Ground (SOG), then check one or more of the boxes (AIS, NAV data). Also check the "Perform Checksum Test" to validate the data received from the NMEA source. If you click the AIS button, a list of AIS target types to display appears. In the future this list can be used to filter the AIS targets that are displayed. For now the list does nothing, and all AIS target types are displayed regardless of what is selected from this list.
Within a few seconds of starting the NMEA input, the "NMEA Data" View Menu item will be enabled. This happens when the first retrieval of the data takes place. As soon as a position is received the latitude and longitude text boxes will be updated, and the display will reflect that position. When the NMEA input is activated the latitude and longitude text boxes are locked and can only be changed by the program. The Radar Form does not display the NMEA data steam as it arrives at the COM port, but rather retrieves the data based on the "NMEA Refresh Rate" setting in the Radar Menu. After the initial NMEA data input has started that refresh rate can be changed using the "NMEA Refresh Rate" Radar Menu item (Fig. 3).
Once the "NMEA Data" View Menu item is enabled it can be clicked to open the "NMEA Data Form" (Fig. 4), which displays data from the NMEA souce in addtion to the GPS items shown on the radar form.
Most of the screen captures on this page were taken on a PC that was connected to a GPS only, so there is no data from instruments or AIS. The AIS processing by the radar display is covered in the next subsection.
The program provides a map of the GPS satellites used to create the position fix (if any). Clicking the "Satellite Map" View Menu item (shown in Fig. 2 on the Radar Display page ) will open the Satellites in View form as shown in Fig. 6. This shows the azimuth and altitude of the GPS satellites relative to the vessel location as reported by the GPS in the GSV and GSA sentences. Each satellite that is in view is plotted on the form. Satellites that are being used to produce the fix are filled circles and the satellites not being used are hollow circles. In addition the signal to noise ratio of each satellite's transmission is color coded as follows:
Red - SNR <15 db or satellite not used for fix.
Yellow - SNR >= 15 db and < 25 db.
Green - SNR>= 25 db
Clicking on any of the satellite icons will display information on that satellite. Below the map is a graph of the SNR for each satellited used to produce the fix.
This feature of the Radar form is activated when the GSA NMEA sentence is received. This sentence is produced by most GPS receivers. However, if the GPS is not connected directly to a PC port, the GSA sentence may not be received. In Fig. 5 the NMEA Data form shows no satellites ("Nr Sats"=0). That screen capture was taken on my navigation computer which receives NMEA data from a Brookhouse Multiplexer. The Mux converts Raymarine SeaTalk to NMEA, but only generates the RMC sentence for GPS data. Therefore the Satellite Map is not available on this computer. PCs that receive GPS data from an AIS Receiver/Transponder may have the same limitation.
LightListManager User Guide
