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Data Hacking

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Chapter 10 — More <strong>Data</strong> Tricks<br />

This window is dynamic and the signal quality bars increase and decrease according to the current<br />

SNR. The window will expand and contract to accommodate the number of satellites in<br />

view at any one time.<br />

NMEA Command Monitor<br />

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

FIGURE 10-44: The NMEA Command Monitor window enables you<br />

to see NMEA commands output by the GPS.<br />

Experiment for Yourself<br />

If you have programming experience, you might be wondering whether you can put your existing<br />

skills to use in the GPS field. You can, but I’ve found that good examples are usually few<br />

and far between.<br />

However, I have found one place that does make code examples and information available —<br />

and freely available at that. Again, this is on the VisualGPS website and the project is called<br />

NMEAParser. Details and code are available at www.visualgps.net/Papers/<br />

NMEAParser/default.htm.<br />

Another site that you might find useful in helping you to program your own GPS software<br />

tools and utilities is www.adelpha.com/~davidco/FarStar/nmea083.htm, where you<br />

will find more information and tools.<br />

The NMEA standard itself is published by the NMEA. Unfortunately, full details of the standard<br />

costs over $200. Fortunately, you can find resources available on the Internet. One of the<br />

best I’ve come across is http://vancouver-webpages.com/peter/nmeafaq.txt.<br />

For more information on NMEA, also see Chapter 9.<br />

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