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Comparison of GT-31 Alphas with smoothing OFF on o

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Caution: Technical GPS stuff inside.

My initial testing on Alpha runs with the GT-31 produced some pretty strange speed graphs for the Alpha's, especially with trackpoints. (Which was disappointing as with the GT-11 the trackpoints seem to produce the more realistic results)
I had no evidence for an explanation until now but we thought it would be to do with the sirf3 chips internal filtering.
Testing on the weekend with one GT-31 with a new firmware that allows 'smoothing' to be turned OFF in the chip shows our hunch was correct.
With the smoothing turned off the results from the GT-31 were very consistent with the trackpoint results from the GT-11 also worn at the time and don't show the strange artifacts that the GT-31 with the smoothing ON shows. See this screenshot of two GT-31's side by side. One with smoothing turned off (Top):

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This is a comparison between two side by side GT-31 Tracks. Alpha 500s. I had seen before that the trackpoint results and graph from the GT-31 (bottom)looked very wrong but I could not explain it. Now it seems that it is to do with the smoothing in the Sirf3 chip. The latest firmware that Tom is testing allows the smoothing to be turned off and this is what you see in the top GPS graph. It is obvious that the top gps result is much more realistic and compares very closely with the Trackpoints from the GT-11 I also was wearing at the time.