I happened to drive around in my van to test a new $30 phone for use with GPSLogit, and ended up coming to some insights about the spikes in 5 Hz GW-52 data. Bottom line is that there is a lot of additional noise when recording at 5 Hz when compared to 1 Hz data from GT-31s. Not all of the speed variations we see at the 200 ms level is real - maybe very little of it is. So the actual improvement in accuracy that is achieved by recording at 5 Hz rather than 1 Hz is definitely smaller than the theoretically possible factor of 2.2. I attached an image that illustrates the measurement noise in 5 Hz data.





The full report is at boardsurfr.blogspot.com/2016/07/dead-toys-and-lots-of-noise.html (scroll down a bit to get to the GW-52 stuff).