Chapter 10 — More Data Tricks 251

This window is dynamic and the signal quality bars increase and decrease according to the current SNR. The window will expand and contract to accommodate the number of satellites in view at any one time.

NMEA Command Monitor

This window enables you to see NMEA sentences as they are being received (see Figure 10-44).

FIGURE 10-44: The NMEA Command Monitor window enables you to see NMEA commands output by the GPS.

Experiment for Yourself

If you have programming experience, you might be wondering whether you can put your existing skills to use in the GPS field. You can, but I’ve found that good examples are usually few and far between.

However, I have found one place that does make code examples and information available — and freely available at that. Again, this is on the VisualGPS website and the project is called NMEAParser. Details and code are available at www.visualgps.net/Papers/ NMEAParser/default.htm.

Another site that you might find useful in helping you to program your own GPS software tools and utilities is www.adelpha.com/~davidco/FarStar/nmea083.htm, where you will find more information and tools.

The NMEA standard itself is published by the NMEA. Unfortunately, full details of the standard costs over $200. Fortunately, you can find resources available on the Internet. One of the best I’ve come across is http://vancouver-webpages.com/peter/nmeafaq.txt.

For more information on NMEA, also see Chapter 9.

252 Part III — Data Hacking

Summary

This chapter described how you can play with the data that comes out of your GPS and use it to do interesting things, some of which have nothing to do with navigation!

Now it’s up to you to get out your GPS, hook it up to a PC or handheld device, and start experimenting!