Chapter 9 — Examining the Data 211

FIGURE 9-7: Playing back NMEA sentences

RECSIM III

Finally, let’s take a look at some software that enables you to simulate NMEA sentences for yourself with no GPS required! This is called RECSIM III (see Figure 9-8), and an evaluation copy is available for download from www.effective-solutions.co.uk/recsim.html.

FIGURE 9-8: RECSIM III

212 Part III — Data Hacking

RECSIM III is an NMEA generator that can create all sorts of GPS data for you. If you have a license, if can even send data via the serial port. Even the evaluation copy allows you to customize the type of output that the software generates (see Figure 9-9).

FIGURE 9-9: Customizing NMEA output

In addition to that, RECSIM III enables you to generate NMEA data based on simulated course and speed data (see Figure 9-10).

FIGURE 9-10: NMEA data simulating course and speed

Finally, to make the simulation even more realistic, you can also get RECSIM III to add an error into the NMEA sentences that it outputs, so that the course information it generates is closer to its real-world counterpart (see Figure 9-11).