Pirated radio waves

I like to wade through the mountain of data that my GPS watch collects during races. I found something interesting while looking at the data from the USAF marathon: someone else’s heart rate. This is not uncommon, especially when there are thousands of people crammed into the starting area of a race. Heart rate monitor receivers pick up whatever is the strongest nearby signal, and if you are not wearing a HRM transmitter of your own, there’s a pretty good chance that someone around you might be wearing a compatible model.


From the graph above, it looks like I picked up three stray HRM signals (shown by the red line). For most of the first mile, I was running near a robot whose heart rate was under 80 bpm (either that or the signal was intermittent). Then a short time later I picked up another signal for another mile or so. Then finally I picked up another for a very short time before the 3 mile marker.

Is this what is meant by a sense of community among runners?

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