My apologies in advance, but I cannot not do this .. here's a pop quiz:


1. One GPS is GW-52, one is a GW-60 - which is which?
2. Why are the tracks so different?

Peeking at my blog to find the answer is cheating!

Merry Christmas!

I was going to say filter , but then I checked the blog

For sure something with noise i guess :)

Is that 5Hz data?

you can clearly see your stride is around 75cms ( if a@ 5hz)

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sailquik said..
Is that 5Hz data?

Yes.

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Simon100 said..
you can clearly see your stride is around 75cms ( if a@ 5hz)

Well done Simon, in that case watch on wrist is traveling further than Gw52 on body, which means blue is watch red is gw52?

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decrepit said..

Simon100 said..
you can clearly see your stride is around 75cms ( if a@ 5hz)

Well done Simon, in that case watch on wrist is traveling further than Gw52 on body, which means blue is watch red is gw52?

We have a winner! Yes, that's it. My first thought also was some kind of filtering thing, but I could see that this happened when I was walking along a sand bar, which made it a bit easier to come to the right conclusion.

I looked a bit at traces and aligned SDOP graphs for 4-unit drives (2 each GW-52 and GW-60), and did not see any obvious difference in filtering or accuracy. There are different sections where one or two units have worse accuracy, and that's usually quite obvious in the doppler speed traces; but the units take turns in "being bad". It may have to do with small difference in GPS reception (this was an "inside the van" test). I plan to do a few more tests with units on top of my van where reception should be completely unobstructed in a few weeks, when we get to warmer and less wooded climates. But so far, so good .