This feature will
allow you to connect any NMEA compliant GPS device
to your computer via USB or serial port that
conforms to NMEA data standards (that includes
virtually all modern GPS units). The live GPS
position indicator is selectable and will change
as you move on the map. Successful operation of
this feature assumes that you have chosen a radar
location that is in proximity with your current
been tested with several commercial GPS devices
that support the NMEA communications protocol. If
you have a GPS device, check the manual to see if
it offers live data via a USB port or serial (COM)
port. Chances are you will be able to make it work
If you don't have a
GPS device, many low cost USB enabled models are
available, many are under $100. StormPredator also
offers a "ready to run" GPS unit at our website
for purchase separately for or as a bundle with
the StormPredator Version 3.5 program.
Here is what the
preferred USB enabled GPS device that we offer for
sale looks like:
It features a
magnetic base and waterproof operation for ease of
use on the rooftop or dashboard of a vehicle. For
details on this GPS unit or to purchase it, please
You'll see a description there and option to buy
the GPS unit shown above.
You should install
your GPS device on your PC with whatever drivers
the manufacturer may provide with the unit. Many
units (including the one offered by
StormPredator.com) have a Windows utility program
to test operation prior to use with other
programs. If you use such a program, be sure to
note what COM port number the GPS has been
assigned to on your PC, and if the data
communications parameters are set to anything
besides the common default of 4800, 8,N,1.
Some GPS units may
conflict with other previously installed USB to
Serial port bridge devices and/or drivers. Be sure
to check your manufacturers troubleshooting guide
for such issues if they occur. StormPredator
support cannot assist you in connecting a GPS unit
(other than one purchased from StormPredator.com )
since we can't possibly be versed with the dozens
of different brands and the device drivers that
are currently available.
manufacturer's suggestions for operation.
Generally, GPS units will not work indoors or if
they do, perform poorly. Testing GPS operation is
best done outside with a laptop and a clear view
of the Southern sky.
Understanding GPS Operation in StormPredator
supports mobile GPS devices that are connected to
the computer via a USB or serial port. The
standard default baud rate of 4800 Baud, 8 bits,
no parity bit, and 1 stop bit (aka 4800 *,N,1) is
supported for easy plug and play communications
with most GPS devices.
Here is a point by
The program will
display a user-selectable icon on the main display
at the coordinates reported by the GPS. On the
image below, note the circle/box icon near the
center of the image to the NW of the city of
Chico. Note also the green
status indicator in the lower portion of
The user enables or
disables GPS support in the Settings>Display
The main display
has the text "GPS" in the button pane when the
user has enabled GPS support.
- If the text
appears in red
then the GPS feature is enabled, but the
program is unable to communicate with the
device. See the Troubleshooting section for more
- If the text
appears in yellow
then the GPS feature is enabled and the
program detects data on the serial port, but the
data does not appear to conform to NMEA
standards. This could mean that the device does
not report the correct information or that the
port settings are incorrect. See the
Troubleshooting section for more information.
- If the text
appears in blue
then the GPS data is valid, but the
device has not locked on to enough satellites to
determine the location
text appears in green
then the GPS GPS feature is enabled and
working normally, The program detects and is
using GPS data from the serial port.
normal operation the text will appear in RED or
YELLOW when the program starts, until all of the
history images have been obtained and any
publication has been completed. Then, the GPS
data will be polled and the status should change
to BLUE or GREEN and the selected icon will be
It is normal for GPS devices to lose their
satellite lock on occasion. Weather conditions,
driving through tunnels or canyons, etc. can cause
the GPS device to lose lock.
When this occurs, the status text will turn BLUE.
condition lasts for more than 5 seconds, the
status text will begin to FLASH, notifying the
user that the current icon location may not be
When the GPS device regains lock, the status text
will automatically return to GREEN.
You may unplug your GPS device from the computer
at any time.
The status text will, in that case, turn RED.
When you plug the device back into the computer
(be sure to use the same USB port), it will
automatically recover and begin processing data.
IMPORTANT NOTE: it is critical that you
plug the GPS device back in to the same USB
port from which it was unplugged. If you plug
it in to a different port, it may be assigned to a
different COM port, and must be reconfigured as
Configuring the GPS in StormPredator
Check your GPS device's software or use the
Windows Control Panel's Device Manager to find out
what COM port to which your GPS device is
If you use the Device Manager, look for a
USB-to-Serial device, and view its Properties to
find the assigned port. Below is a screencap of
the Windows 7 Device Manager dialog with the
device for our preferred USB enabled GPS device
shown configured as COM3. in the yellow highlight.
Other USB enabled GPS devices will show up in a
similar way, once the device driver is correctly
device ports are configured by pressing the
Settings button on the main Storm Predator
windows, then pressing Display for the "Display
Options" dialog. To enable the GPS device, be sure
the "Enable GPS Locator Device" box is checked.
"Settings" button to the right of "Enable GPS
The port configuration and icon selection dialog
Most off the shelf
GPS devices have a default communications settings
of 4800 Baud, 8 bits, no parity bit, and 1 stop
bit (aka 4800 *,N,1) If needed, change the default
settings to match your GPS device communications
parameters and the COM port it is operating on.
Pressing the Browse
button allows the user to select an icon for the
GPS locator. Some special icons designed for use
with GPS have been added with Version 3.5 and
begin with the letter "z" which will be at the end
of the list. But you can use any icon you wish for
the GPS locator.
In the GPS configuration dialog, pressing the Test
button will invoke a GPS serial port test.
Pressing the Start button initiates the test.
The output is verbose, and includes all data
received from the port.
This is to allow users to troubleshoot potential
For example, if the baud rate or parity is
incorrect, garbled characters will appear.
The text scrolls indefinitely as data is received.
The test may be paused and restarted at will.
Pausing the test allows users to analyze the text
in the display without it scrolling out of view.
If you see an error message stating that the
handle is invalid, then the program cannot detect
a GPS device connected to the specified port.
This may be because the device is unplugged, the
wrong serial port was specified, or the serial
port communications parameters are incorrect.
Troubleshooting and technical information
StormPredator supports all GPS devices that
conform to NMEA (National Marine Electronics
Association) standards and that also have a USB or
serial data output.
For complete NMEA standards information and other
technical information, please see the NMEA web
site at www.nmea.org
You must install a USB-to-serial driver specific
to your GPS device and connect the GPS device to
the computer running StormPredator via a USB
When those are installed, use the GPS's Windows
application to get the port parameters, or refer
to the Windows Control Panel's Device Manager to
determine the port.
When you press the Test button in StormPredator's
GPS configuration dialog, another dialog appears
that displays the currently selected serial port
Press the Start button to begin communicating with
If you see garbled data, then something is wrong
with the port settings.
Things that most commonly go wrong are incorrect
baud or parity settings.
You may also have specified the wrong serial port.
Refer to your GPS device's documentation for more
information about the correct settings for your
When the data begins streaming to the window, you
will see something similar to the text below:
Each line of this data is referred to as a
StormPredator is only concerned with the GPRMC
This sentence contains all of the information we
need to plot a marker and determine the status of
the GPS device.
The lat/lon values are present in several NMEA
sentences, but some of them are not included in
some GPS devices.
The GPRMC sentence is almost universally provided
by GPS devices.
Once you have data streaming that appears similar
to the above, you can tell the test function to
filter the data to display only the GPRMC
We recommend that you only use that feature to
troubleshoot satellite communications problems
between the GPS device and the GPS satellites.
You may press the Stop and Start buttons to pause
the data for further analysis or for copying the
data to the clipboard.
If you do not see lat/lon values in the GPRMC
sentence, check the Satellite Fix Status word of
If you see a "V" in that word, then the GPS has
not "locked on" to enough satellites to determine
the lat/lon of the GPS device.
See the technical description of the GPRMC
sentence below for more information.
GPRMC Sentence Technical Information
All NMEA sentences begin with a dollar sign ("$").
The GPRMC sentence consists of twelve
The command word indicates that the sentence is to
be interpreted as a recommended minimum message.
GPS devices are able to calculate the current date
and time using GPS satellites (and not the
computer's own clock, making it useful for
synchronization). This word stores the current
time, in UTC, in a compressed form "HHMMSS.XXX,"
where HH represents hours, MM represents minutes,
SS represents seconds, and XXX represents
milliseconds. The above value represents
04:03:02.663 AM UTC.
Satellite Fix Status
When the signals of at least three GPS satellites
become stable, the device can use the signals to
calculate the current location. The device is said
to be "fixed" when calculations of the current
location are taking place. Similarly, the phrases
"obtaining a fix" or "losing a fix" speak of
situations where three signals become stable or
obscured, respectively. A value of "A" (for
"active") indicates that a fix is currently
obtained, whereas a value of "V" (for "inValid")
indicates that a fix is not obtained.
Latitude Decimal Degrees
The latitude represents the current distance north
or south of the equator. This word is in the
format "HHMM.M" where HH represents hours and MM.M
represents minutes. A comma is implied after the
second character. This value is used in
conjunction with the longitude to mark a specific
point on Earth's surface. This sentence says that
the current latitude is "39°39.7'N".
This word indicates if the latitude is measuring a
distance north or south of the equator. A value of
"N" indicates north and "S" indicates south. This
sentence says that the current latitude is
Longitude Decimal Degrees
The longitude represents the current distance east
or west of the Prime Meridian. This word is in the
format "HHHMM.M" where HHH represents hours and
MM.M represents minutes. A comma is implied after
the third character. This value is used in
conjunction with the latitude to mark a specific
point on Earth's surface. This sentence says that
the current longitude is "105°06.6'W".
This word indicates if the longitude is measuring
a distance east or west of the Prime Meridian. A
value of "E" indicates east and "W" indicates
west. This sentence says that the current
longitude is "105°06.6'W".
This word indicates the current rate of travel
over land, measured in knots.
This word indicates the current direction of
travel over, measured as an "azimuth." An azimuth
is a horizontal angle around the horizon measure
in degrees between 0 and 360, where 0 represents
north, 90 represents east, 180 represents south,
and 270 represents west. This word indicates that
the direction of travel is 358.86°, or close to
GPS devices maintain their own date and time
calculated from GPS satellite signals. This makes
GPS devices useful for clock synchronization since
the date and time are independent of the local
machine's internal clock. This word contains
two-digit numbers for days, followed by months and
years. In the example above, the date is August
(08) 20th (20), 2004 (04). The two-digit year is
added to 2000 to make a full year value.
This word denotes the magnetic variation from True
North. This value varies by latitude and
longitude. This word may not be included in some
GPS models, as in the above example.
The checksum is used to identify errors in the
data which may have occurred during transmission.
It is a simple accumulation of the total decimal
ASCII values of each character in the sentence.