Forums > Windsurfing   Gps and Speed talk

Measuring speed errors: sampling frequency

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Created by boardsurfr 3 months ago, 29 Jan 2022
boardsurfr
WA, 1572 posts
29 Jan 2022 12:04AM
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In the "GPS Accuracy" thread, the issue was raised that the sampling rate itself can introduce speed errors, so I went and had a look at how much the top speeds differ if we look at the same sessions at 10 Hz, 5 Hz, and 1 Hz. Here is a graph that illustrates the measurement of a top speed at the three different rates:



The next graph summarizes the average differences, looking at the top 5 results from 10 different files in 3 GPSTC categories:

For comparison, the red bars show the average differences between sessions recorded with 2 different 10 Hz units from 5 sessions by 3 different speedsurfers. Here's the same graph for the maximum differences measured:


The measured differences between 5 and 10 Hz data are smaller than the differences between 2 units (which are already quite small, especially for 10 seconds and longer).

A more detailed description with plenty of numbers is at boardsurfr.blogspot.com/2022/01/measuring-speed-errors-sampling.html



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Forums > Windsurfing   Gps and Speed talk


"Measuring speed errors: sampling frequency" started by boardsurfr