Speed

GPS is inaccurate. It measures positions only with a exactitude of about 10 m. Therefore, speed measuring also has the flaw of possibly being inaccurate.

The solution is: smoothing speed values. Run.GPS uses an adaptive buffer which automatically adapts to the currently required accuracy.

A value of 30 seconds makes sense for speed smoothing buffer size. If you need more stable speed values, you can increase the buffer size.

"Static Navigation"

Another important issue is "static navigation". Some GPS receivers have "static navigation" enabled as a factory default. "Static navigation" means that low speed values are truncated. This is okay for car navigation, but not okay for pedestrians. The result of "static navigation" is inaccurate and oscillating speed values when you're going at speeds below 8 kph.

There are two well-known tools to turn off "static navigation" for SIRF-III chips:

• MMSirf, http://www.memory-map.com/MMSirfSetup.exe
• APLSirf, http://www.gpspassion.com/download/APLSIRF-0-0-0-2.zip

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