Dennis Milbert
Updated: 2005-aug-09
The program, GarNMEA2, collects the NMEA output fed to your
PC serial port, COM1, into a file.
Operation
First, you will need to compile this puppy. The compiler (and run time environment) is available (for free) at java.sun.com/products. Use the standard edition SDK (micro is for tiny devices, and enterprise is for business). After download, installation is a two/three-click operation. Also, since this is doing RS232 communications, you will need to download the optional Java Communications API (http://java.sun.com/products/javacomm/index.jsp). To compile, put the Java source in a subdirectory, and compile GarNMEA2.java in a DOS window:
> javac GarNMEA2.java <------- WARNING -- case sensitive
To execute in the DOS window, type:
> java GarNMEA2 <------- WARNING -- do not add .java extention here
The program will then log COM1 to the output file.
One file is generated as output. It's name is nmeaout.txt. The file will be in the subdirectory where you are working.
Input:
A serial cable from the handheld to the COM1 serial port on your PC.
Be really, really sure that your handheld is set to transmit NMEA, 4800 baud.
Output File:
nmeaout.txt -- ASCII, NMEA format.
Discussion:
The program runs in an infinite loop. To stop the program, press
"ctrl" and "c" at the same time. The communication parameters are
COM1 port, 4800 baud, 8 data bits, parity-none, 1 stop bit. These can
be easily changed in the source code.
NMEA Format
The official source for the NMEA 0183 standard is
NMEA.
They do charge for the document.
In addition, there are
an abundance of sites on the web that discuss NMEA.
Check out the links further down on this page.
Shortcomings
This is "no frills" software. There are no warranties of any sort. No Windows GUI. Just the core function.
The program will overwrite any existing "nmeaout.txt" file in the working directory.
Stopping with a "ctrl-c" is not elegant. And, the comm parameters are
hardwired.
Source Code
The Java source code is GarNMEA2.java.
Links to Other Pages
The links here are for some other sites that talk about NMEA. This list is by no means exhaustive.
Walter Piechulla: "Understanding NMEA 0183".
Glenn Baddeley: "GPS-NMEA Sentence Information".
Klaus H. Hirschelmann: "NMEA 0183".
Peter Bennett: "NMEA-0183 and GPS Information".
To Contact Me
My e-mail user name is the first initial of my first name
followed by all the letters of my last name (see above). My ISP is
"comcast", and it is a "dot-net", not a "dot-com". Sorry for not spelling
out my e-mail address, but I try to keep the spam-bots
from fingering me. But, just so the spam-bots don't feel left
out, they can always go to abuse@comcast.net