GPS Matters

At work so today’s walk was a few laps around the main building at work. I tracked the walk with Endomondo running on my phone, which was in my pocket.

As I was walking around the previously measured 1/4 mile course, I noticed that Endomondo was claiming that I hadn’t walked as far as I should have.

Back home, post-walk, I downloaded the track (in blue) and superimposed the actual route followed (shown in red.) As you can see, there is some discrepancy.

  • The route (16 laps) should be 4.00 miles
  • The reported route was 3.66 miles
  • I ‘lost’  0.34 miles during a 4 mile walk – a loss of 8.5% !!!

This got me thinking…
An interesting site that I came across was fellrnr.com (short for fell runner, I guess.) Here various GPS watches, smartphones and even the humble footpod were compared.
The main points, I think, are…
  • GPSs are quite accurate in straight lines (I did lots of turns)
  • Accuracy depends on location of the device on the body (trouser pocket)
  • Smartphones are generally better than dedicated GPS watches
  • The most accurate is… drumroll… the footpod (once calibrated)
Of course, the footpad, while very good at recording distance, time and therefore pace does not record where you’ve been. The best choice would be GPS AND footpad. However, using just the footpad with suitable watch would provide excellent pacing and much prolonged battery life (handy on a long event.)
With my new (surprise) birthday pressie (Garmin Forerunner 230) due this week, I’ll have to see how this compares. Perhaps I’ll have to invest in a footpod to compliment the GPS watch?
Week Total = 50.67 miles

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