Configuring Serial GPS Ports

GPS receivers are connected through a computer serial port (RS232 or USB).

To add a new GPS port, click the Add button on the Configure Ports tab. The port editing dialog will appear. Set the port type to Serial_GPS.

The other parameters you will need to specify for the GPS receiver are:

• the name of the port to which the GPS is connected. On Microsoft Windows, this will be a COM port (COM1, COM2, etc.). On Linux, this will be a /dev/ttyS port (ex. /dev/ttyS0) or a USB serial port (ex., /dev/ttyUSB0), although some "hockey-puck" USB GPS devices appear as /dev/ttyACM0 and the console port on a Raspberry Pi appears as /dev/ttyAMA0. Similar device names will be used on other Unix derivatives. Note that on Linux and Unix systems, you will need the access right to access serial ports. Typically, this will be membership in a group owning the serial ports, such as dialout, tty, or uucp.
• The baud rate the GPS receiver will be communicating at (typically, 4800 baud, though you may wish to configure your receiver for a higher speed). Ensure that the GPS receiver is set to the same speed as you configure this port to.
• Whether YAAC should transmit waypoint messages back to the GPS to display APRS stations and objects on the GPS screen, and, if so, which message format should be used (standard GPS waypoints, or the Kenwood proprietary message understood by the AvMap GPSs).
• Whether the GPS is local (reporting the position of the station running YAAC) or remote (reporting the position of some other object using a long serial link). The remote option is useful for situations such as amateur rocketry, where an unlicensed ISM band link is used to relay the serial GPS data from the rocket to the ground station, and the ISM receiver looks like a USB serial port to the ground station's computer. In addition, for remote GPS receivers:
  • the text name to use for displaying the remote GPS on the YAAC map.
  • the APRS symbol to use for displaying the remote GPS on the YAAC map.
  • whether or not the remote GPS should also be transmitted to the APRS networks as a locally-originated APRS Object with the specified name and symbol.

The "Test Port" button provides a means of verifying that you have connected to the correct place; it opens a terminal window connected to the configured serial port so that you can manually test the GPS receiver for the desired operation. To complete testing, close the terminal window.

Once you have the settings the way you want them, click the Save button.

You can check how well your GPS receiver is performing by selecting the menu choice View -> Show GPS Status.

If you want to create a Serial_GPS port on a new installation of YAAC using the -createport option, the port_description is of the format:

where comportname is the name of the serial port on your operating system, such as COM3 or /dev/ttyUSB0, and baudRate is the serial port speed; this must be specified even for USB devices that don't have a configurable baud rate. The flags are a decimal number of 0 for a local GPS, 4 for a remote GPS, and 6 for a remote GPS that should be transmitted periodically to the APRS network as an APRS Object. If the GPS is remote, the callsign field will identify the name the remote GPS will be plotted on the map and transmitted as the APRS Object name. If the remote GPS is to be transmitted, then the remote-APRS-symbol must be specified as two characters of the symbol table ID ('/' or '\') or overlay character followed by the symbol code (note that symbol code ';' cannot be used because of the syntax of the port_description string). If the connected GPS has a map screen of its own, received APRS stations and Objects can be plotted on the GPS as waypoints by specifying the waypointchoice as 0 for no transmission to GPS, 1 for transmission as $GPWPL sentences, or 2 for transmissions as $PKWDWPL sentences (only understood by the AvMap GPSs).