This is a screen grab of the Polar S625X used for a group interval training run. Please click the image for a bigger, clearer screen shot

You may see there are a couple "spikes" in this graph, both pace and heart rate. These are only minor spikes and could be due to electrical interference. The image below has been through the Polar software and had these spikes removed.

This is a "smoothed" version of the graph above. This graph has had automatic error correction applied to remove the spikes.

The top line is heart rate (red)

The middle line, blue, is speed

The bottom line is altitude

The grey / blue box on the bottom RHS is a lap summary box that pops up when you hover over the lap points.

This graph is here to show how accurate the Polar S625x is. This is a graph from a Garmin Forerunner 201 (GPS) worn at the same time as the Polar S625x.

There are a couple of spikes due to GPS signal loss, nothing too serious.

There is very little to compare between GPS and FOOT POD technology. From experience, Foot Pods generally offer 95-97% accuracy out of the box. GPS may be marginally more accurate, but nothing to worry about.