I've finished analysing the 2sec results from Nigel's Fenex3 files.
From the Kyeemagh session I get these differences to his GT31 in 23 runs

-0.075, -0.339, 0.007, 0.2, -0.494, -0.298, 0.122, 0.152, -0.277, -0.533, 0.072, -0.168, -0.2, 0.195, 0.121, 0.112, -0.039, -0.152, -0.015, -0.11, -0.136, 0.234, -0.063
Max difference 0.533knts

For the Sanctuary Point session I get these differences to his GT31 in 24 runs
-0.75, -0.778, 0.349, 0.025, 0.421, -0.018, 0.661, 0.579, 0.348, -0.205, -0.658, -0.079, 0.018, -0.812, 0.093, -0.515, -0.274, 0.571, -0.263, 0.165, 0.187, 0.26,7 -0.167, 0.119
max difference 0.778knts

And looking at the doppler speed graphs in GPSarPro is this a sign of the underhand effect?
Nigel, do you use the underhand grip?
Blue GT31, red Fenex3



You can see that the first and third runs are a bit spiky but the 2nd and 4th runs follow the GT31 better. The offset is due to a slight time stamp difference

for christ sake Decrepit !!!

It's FENIX like the bird not like the desert fox !!! LOL


just kidding, nice work on the analysis; I might have a new device to test soon, will send you the track to check. Thanks again

Well there's not enough data here yet to base any conclusions on. I just wanted to assure Nigel we are slowly working on it.
I was wondering if it was "i" or "e", but it was too hard to check, so you're stuck with my best guess.

But why when you load garmin files on ka72 it robs 2-3knots from the speed on the screen when both the gt31 and garmin device are reading within .4of a knot

Select to expand quote

Benda said..
But why when you load garmin files on ka72 it robs 2-3knots from the speed on the screen when both the gt31 and garmin device are reading within .4of a knot

What model Garmin is it?

Do you mean the peak speed on the screen reads very close to the GT-31? (But I would say 0.4kt is not really that close.)

If you would like to send me the files from both I can have a look to see if something stands out. (PM me for email)

Do other analysis programs give the same difference as KA-72?

Thanks Mike :) Yes, I use an underhand grip. I also have my GT31 strapped to my seat harness on my hip, so it might not be very accurate. I guess if I wore both devices on my head it would make the comparison data more legitimately comparable. Anyway, I'll send you some more files as I get them, Mike. Appreciate your work buddy.

Hey Gav, I'm not sure why you got an anomaly with your Garmin. I've never had any issues with the Fenix and KA72.

Gav, one thing I could think of to double-check is that you use 1-sec recording instead of smart recording. I'm not sure if that is the reason but maybe? I could check your .fit file if that was the case if you want. Send it to mciragan@gmail.com. The activity profile should be based on "Other" and not "Running" or so.

hey if you guys are interested i currently have a ublox 8 and a venus 838 @ 50hz wired up to some logging equipment that also logs the speed directly off one of the abs sensors in a car and accelerometers if you want some graphs comparing the gps speeds with the wheel speed i can throw a canmore and gt31 on there too i guess. Maybe i could drive how we windsurf and see the variations.If you have any sugestions let me know.

PM'ed you.

Hey mate thanks for that ill check that when imm back home imm away at work for another 10 days ill flick you the files then . idd find that in the settings of the watch or in the app that i down loaded to the watch?have a good easter