GPS Menu commands

Digital Atmosphere supports the use of Global Positioning System devices. Your GPS unit will need to output data in NMEA format. What you do with these instruments and how they can work with Digital Atmosphere is limited only by your imagination. With the digital raster graphics supplied with Digital Atmosphere, you can have moving maps suitable for storm chasing or even activities that don't even have a meteorological purpose. We've added the functionality, and it's up to you how you'd like to use it.

The topmost menu selection is not a menu choice but is instead a readout of the GPS status. It will show one of the following:

• Idle - The GPS device is not in use and has not been selected.
• No comm port - You have chosen a COM port that does not exist, or use of this port is blocked because it is being used by another application.
• No communication - The port is open but the GPS is off or is not hooked up.
• Communication - A GPS has been sensed, but no data is being read.
• NMEA - Valid data blocks have been read from the GPS device.

Instructs Digital Atmosphere to use the COM port and begin reading GPS data. You will need to determine which COM port the GPS is hooked up to. Refer to your system setup documentation or use trial and error to find a valid port.

Instructs Digital Atmosphere to cease using the COM port and discontinue the reception of GPS data.

If enabled, Digital Atmosphere will redraw the weather basemap whenever the current position is within 20% of the screen's edge. Leave this unchecked if you want to have manual control of Digital Atmosphere at all times.

In this panel, you set the baud rate, data bits, parity, and stop bits. Obtain these from the setup menu in your GPS. It is recommended you use 4800 baud, 8 data bits, N parity (none), and 1 stop bit. The setting will be remembered the next time you start Digital Atmosphere.

Please be aware that the mouse cursor will act erratically if the GPS is connected and running while Microsoft Windows is loading. This is an extremely common problem in Windows due to deficiencies in the Plug and Play drivers, and has been exhaustively documented by GPS users. Try one of the most common fixes used by GPS users:

1. Temporary - Leave the GPS unplugged whenever Microsoft Windows is loading.
2. Permanent - Go to Control Panel > System > Hardware > Device Manager > Mouse & Pointing Devices, and click on Microsoft Serial Ball Point, then choose Actions and Disable. If this does not work, you can try opening the device manager after an erroneous startup using the keyboard, find which mouse driver is being used, and disable that.
3. Find other suggestions at http://groups.google.com/groups?q=sci.geo.satellite-nav .

Most GPS units are built with antiquated serial ports, thus the support in Digital Atmosphere for this protocol. If your computer does not have a serial port, you may buy a USB Serial Adapter, which brings in serial data through your USB port. Belkin is one of the largest makers of such boxes. They cost about $30.