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May 2015
11:24pm, 14 May 2015
15,853 posts
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flanker
ah, with you now. Yes, can only calibrate against a known altitude. In someways it makes more sense as it is constant while pressure at sea can vary (even if you use the usual 15 year averages).
Best thing about the nav is they've sorted the fault of the 310/910 where if the trackpoint distribution was 'wrong' it wouldn't display the track.
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May 2015
11:37pm, 14 May 2015
4,976 posts
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Badger
That was a real pain. Have you tried using a course with turn marker coursepoints off something like ridewithgps? Bit fiddly to get a TCX on (you can do it with GTC, or I've written a program to convert the TCX to a fit course), but you get a full screen alert with a big fat arrow a few seconds ahead of the turn, repeated as you reach the turn. Really nice.
Calibrating by height is best if you know your elevation, but if you don't then air pressure from a weather forecast makes a pretty good substitute. If you can enter it in the first place...
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May 2015
12:04am, 15 May 2015
15,854 posts
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flanker
Not tried that. Might be something I look at, as I can see the benefits. Spent the last hour looking at the corner-cutting issue and don't seem to be seeing much of it. What I do seem to see though is that (looking on strava not GC), that there tracepoints are quite widely spread, so I assume GC is doing som form of smoothing. Might get down into the raw data one day and have a play with it...
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May 2015
9:08am, 15 May 2015
4,979 posts
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Badger
GC doesn't plot all the recorded points, and the longer the route the more it leaves out. So with your training and racing style you probably get about two points a mile plotted.
Just sent you an email about accuracy.
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May 2015
12:13pm, 15 May 2015
15,857 posts
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flanker
Your email and traces show pretty much what I've been seeing, although more extreme. It seems that with the F3 it almost draws point-to-point lines between readings whereas the older models seem to fit curves. Hopefully this is the case in as that means it's software algorithms rather than hardware that need fixing.
Either that or the sampling rate on the F3 is far less than the other devices as routes don't seem anywhere near as smooth. That would be a far bigger issue, and if so its possible they've had to frig it to get the battery life it needs to compete with the Ambits.
It's a bit of a pain, and would explain why I got Foxy's 26.4 marathon reading 25.7 as that's mulitple laps around a 3-4 mile loop with lots of bends on it, but not enough for me to stop loving the watch.
On the positive side, I'd much rather have it read short than long!
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May 2015
12:23pm, 15 May 2015
4,983 posts
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Badger
It's one-second sampling, same as they have always been. I think it defaults to smart recording, but even that's still one-second sampling so the distance the watch displays will be the same. I can see one point per second in SportTracks.
I noticed once when I was following a course that it showed me still coming up to a side path when I was actually already past it, so I had to double back. The final track showed the double-back hitting the side path accurately, though it showed me turning back earlier than I actually had. That, and a few other things I've seen, make me suspect that when the GPS signal is less than perfect it is recording points a few seconds late to add later readings into the calculation, but changing direction when you change direction, which causes the corner cutting. Bit tinfoil-hat, that, but it's something that should be tweakable in firmware if it's right.
Completely agree about better short than long! It read 25.9 for MK, which is barely more than 1% off in total. Races like that I tend to believe the course markers over the GPS anyway towards the end, 1-2% off is pushing half a mile by then.
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May 2015
9:58pm, 27 May 2015
15,886 posts
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flanker
Official post on the Garmin support forums...
Garmin stands behind the fenix 3 and the satisfaction of our customers. Any customers experiencing issues with their device should contact their local support center. If after review the device is determined to be defective, Garmin will replace the device at no charge.
Additionally, Garmin is working to validate a firmware update to improve performance in regards to distance accrual that has been witnessed by customers in specific situations.
Please continue to be patient with us as we continue to work through this.
US By Phone
U.S.: 913-397-8200
U.S. Toll-free: 800-800-1020
Canada: 866-429-9296
Support Hours
Mon–Thurs: 8 a.m.–6 p.m.
Fri: 8 a.m.–5 p.m.
Central Time (Closed Holidays)
UK By Phone
Freephone from UK landline: 0808 238 0000
Within UK: 0870 850 1242
Outside UK: +44 870 850 1242
Support Hours
Mon–Fri: 8:30–17:30
Western European Time (GMT/UTC)
"to improve performance in regards to distance accrual that has been witnessed by customers in specific situations"
i.e. when you want it to measure distance in that specific situation that involves you being in motion.
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May 2015
11:05pm, 27 May 2015
5,037 posts
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Badger
That's very unfair. If you are moving in a perfectly straight line the whole way, it'll accrue marvellously.
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Jun 2015
1:29am, 10 Jun 2015
15,921 posts
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flanker
June 5th comes and goes
*drums fingers*
*loses miles*
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Jun 2015
10:54am, 10 Jun 2015
1,585 posts
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monsenb1
I was saving up my pennies to buy an F3, but after all this palaver I decided to go old school and buy a 310xt in amazon for only 115 quid. I spent some of the money i saved on OMM kit, and still have about 200 quid left in the kitty. I reckon by the time my 310xt conks out, they might have sorted out the problems.. 
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