>>8) I don't believe the plot seen above is as useful as folks are making it out to be. It's on a trail run, where the data isn't being provided, and the thousands of 'attempts' are really just runs divided up into tons of tiny little sections. Comparing foot pod to >>non-foot pod is sorta cheating. After all, that's the point of foot pods on trail runs.


When you say "the data isn't being provided," what are you referring to? Are you saying he's not making his raw data available?

I don't see a problem of dividing a run into sections. His method of having discrete landmarks is *much* easier than using continuous ground truth.

And I don't think comparing foot pod to GPS is cheating. Because knowing their relative strenghts and differences informs the consumer about choosing something appropriate for their activities.

While I've heard different issues, this the first I've heard that the innards may be causing an issue.

In any case, I've had a 310XT for some time. At one point I bought a Fenix 2 but when it lopped off over 200m in a 1Km segment (and some other issues), I decided to return it. I've never had the 310 do that - sometimes it is out by 50m over 5Km or so on the route I usually run (I can tell when it signals my turn around at a different point) but that's it.

I borrowed someone's 910 for the last HIM I did. It made me 1/2 an hour slower (OK, maybe my lack of training contributed to that along with a tougher course). Anyway, after that trial I really wanted to get one but I've been telling myself to wait for the next version, hoping for some additional features that I'd like. But, come next Spring, I'll either have a new unit or I'll get a 910.

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BC Don
Pain is temporary, not giving it your all lasts all Winter.

Correct, there's no data files available, nor comparison between units on the same runs.

The challenge with dividing up the data is that the course itself only appears to be 2-3K, so when you subdivide the data into dozens (or more) of smaller sections you start to get to the point where you're getting into questionable territory. Then, the charts imply really high count numbers, but not actual miles ran (or even total runs). So a single 2-3K run is how many 'values'? 100, 200, 15?

It's one of the reasons in many of my reviews I include data from multiple units on a single run/ride and let folks go to town. If you're presenting the data - then actually present the data too, not just an interpretation of it.

Finally, as for footpods, why add footpods for the 910XT but not the 620 and Fenix2? I guess that's sorta my point. One is comparing it to a value that's not 'like'. I have no problem showing the strength of a footpod, but since the tests are "GPS accuracy" and not "Footpod accuracy", it's a bit misleading.

Don't get me wrong - I think he does interesting work, but I just don't like that so much of it's a bit black box and many people are mistakenly believing he's looking at thousands of runs.

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My tiny little slice of the internets: dcrainmaker.com

Unless they were recorded on the same day and time the diffrences could be due to changes in satellite coverage or atmospheric conditions. Trimble have a tool that will tell you when gps accuracy should be at its highest (used for planning surveying).

Noticed at the tour The Garmin cars seemed to have rtk gps aerials

I've loved all my Garmin running watches until I got the Fenix 2. I really wanted to like the watch. But I had too many runs where it was off significantly on "clear" sky runs on measured courses where it would be off by up to 0.4mi on a 6mi run. In all my years with a 910XT, I think the most I'd see was 0.05. My OWS results were up to 30% wrong. I did a tempo run, where I'm pretty good with RPE and pace, and the damn watch had me running a 5:25 pace. I know that I'm not cruising at that pace!

With Garmin dropping Sirf, I've been thinking about what to get since my 910XT is dying slowly. I'll have to check out the V800 - hadn't thought of that one!

I use the velcro wrist strap kit for the 610, feels comfortable to me.

https://buy.garmin.com/...55_010-11251-04.html

Testing GPS accuracy in an open water swim is about the worst possible test for accuracy you can do.

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Rodney
TrainingPeaks | Altra Running | RAD Roller
http://www.goinglong.ca

>Testing GPS accuracy in an open water swim is about the worst possible test for accuracy you can do.

But it's really good for testing the accuracy of GPS in an open water swim.

My point being that GPS accuracy can vary widely according to use-case. Just because a GPS is accurate in the open doesn't mean it's going to be accurate in an open water swim. And vice versa.

DC I seriously like your reviews but this interal GPS issue from SRiF to whatever in house Garmin GPS seems to be the issue and based on this post it is more than FOOT pods and OWS swims....... I appreciate your 10 responses but you are missing one response I would like what do you think of the different internal GPS units.

"I've loved all my Garmin running watches until I got the Fenix 2. I really wanted to like the watch. But I had too many runs where it was off significantly on "clear" sky runs on measured courses where it would be off by up to 0.4mi on a 6mi run. In all my years with a 910XT, I think the most I'd see was 0.05. My OWS results were up to 30% wrong. I did a tempo run, where I'm pretty good with RPE and pace, and the damn watch had me running a 5:25 pace. I know that I'm not cruising at that pace!

With Garmin dropping Sirf, I've been thinking about what to get since my 910XT is dying slowly. I'll have to check out the V800 - hadn't thought of that one!"

DC I seriously like your reviews but this interal GPS issue from SRiF to whatever in house Garmin GPS seems to be the issue and based on this post it is more than FOOT pods and OWS swims....... I appreciate your 10 responses but you are missing one response I would like what do you think of the different internal GPS units.

"I've loved all my Garmin running watches until I got the Fenix 2. I really wanted to like the watch. But I had too many runs where it was off significantly on "clear" sky runs on measured courses where it would be off by up to 0.4mi on a 6mi run. In all my years with a 910XT, I think the most I'd see was 0.05. My OWS results were up to 30% wrong. I did a tempo run, where I'm pretty good with RPE and pace, and the damn watch had me running a 5:25 pace. I know that I'm not cruising at that pace!

With Garmin dropping Sirf, I've been thinking about what to get since my 910XT is dying slowly. I'll have to check out the V800 - hadn't thought of that one!"

As I noted in the review, I swam a limited number of times. It was the middle of winter, and I don't live in a tropical locale. The results are in the review.

On the running front, again, the results are in the review. They're also in every running watch I've reviewed since then - almost all of which show Fenix2 units out on runs comparing other units. They're also in so many other posts I write showing comparison with units ending up at the same distances or within 1% (2% max). I just don't see accuracy issues on the vast majority of my runs, and I run in a lot of places.

I have no doubt that there are people having issues. There are for every electronic device from the iPhone to a dishwasher. Searching for issues, and you're going to find issues. People that are happy don't post they're happy - it's the way the internet works. Same goes for past Garmin devices. Seriously, go search for "FR910XT accuracy issues" or "FR310XT accuracy issues" or...fill in the blank. Basically, it's groundhog day again. Finally, be sure you're looking at the dates of Fenix2 posts. Many people that were having various issues 5 months ago aren't today. There's been tons of firmware updates.

Finally, I think there's quite honestly a lot of threads/posts like this. Don't take this the wrong way, but you're posting a thread questioning/stirring about accuracy issues whereby you don't even have a unit. Go out, get a unit, and try it. If you don't like it - you can always return it.

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My tiny little slice of the internets: dcrainmaker.com

I bought my GF and my mom both Garmin 220's, and have borrowed both on occasion. I don't trust the speed on there any further than I can throw it. I had one run in particular where I recalculated my pace using the watch time and a GMaps distance and my pace/mile went from an 8+min/mi reported on the watch to a 6:45 (much more consistent with my RPE. My 910, on the other hand, reads fairly accurately (I.e my distance matches certified course distances pretty well)

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I tweet!

I'm 100% in agreement with rbuike on this one. Getting accurate OWS GPS with a watch on your wrist is a crapshoot, your arm is underwater most of the time, unable to get a GPS signal and dependent on the brief time your arm is above water to get a signal. Depending on your swim style, stroke rate, etc., accuracy is going to vary widely person to person. I'd guess it would even vary if you're swimming on smooth vs. choppy water. If you want an accurate GPS track, put the watch in your swim cap. If you want your time and only a very rough idea of how far you went, put it on your wrist. I swam a measured course with a watch on my wrist and had nearly a 20% error rate. The concept of "testing" GPS accuracy with a watch on your wrist is just inherently flawed.

Didn't Polar have some widespread GPS issues a week or so ago?

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Rodney
TrainingPeaks | Altra Running | RAD Roller
http://www.goinglong.ca

The 910xt also had a specific open water swim mode that enabled some corrections. Garmin even markets the 910xt as "designed for open water and pool swimming" yet the Fenix 2 gets the Garmin Swim feature set, which didn't include open water features.

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Rodney
TrainingPeaks | Altra Running | RAD Roller
http://www.goinglong.ca

You are missing the point. Agreed, OWS is not the standard for testing GPS accuracy and it shouldn't be used as "control" in any experimentation for all the reasons you identified.

HOWEVER, when the Fenix2 is off by MILES on four different occasions in an actually known OWS course distance and the 910XT is accurate to the hundredth of a mile on two different occasions, you have to say HMMMMM....perhaps the 910XT has better GPS accuracy than the Fenix2 when it comes to OWS. Same swimmer. Same stroke length. Same course. Same time of day. Same wrist. Just different watches.

When it comes to GPS, I assume some variation and inaccuracy. All you need to do to realize this inaccuracy is run/record a few laps around a track in a wide open area to see there are going to be some inconsistencies. Fine. In the end, I am only interested in knowing if I ran 10 miles, 15 miles, or 20 miles when I go out and run for time. I'm not really interested in whether it was 15.1 or 15.2. I know some are and some use it for pacing and racing.

When it comes to the swim, I think we can all agree that if I swam 2.5 miles and my Fenix2 told me I swam 4 miles, the Fenix2 is worthless in OWS. It's not like it said I swam 2.7 or 2.8. That, to me, it acceptable error. Off by 60%? That makes the product garbage.

Just a note to say that your reviews and thoroughness totally rock, and are way appreciated. I don't say this as a backhanded slam against the guys raising questions in this thread, but simply because your answers here have reminded me why I trust your reviews far more than anyone else's.

And I agree that the 1 in a 1000 problems (or maybe an entire batch of units, as in Zack's case above), aren't reflective of the general product. It sucks for whoever gets the faulty ones and I don't blame them for their frustration--but they're problems are usually not indicative of the performance that 99.9% of the rest of us get.

I have a 910xt, 210 and 310xt..... I was very close to getting a fenix2 or a 220 based on your reviews and how they fit..... After reading multiple pages of stuff about a fenix2 and the internal GPS issues I went with 910xt.

DC rainmaker do you think the new internal GPS change from SRiF has anything do with these issues? Please give us insight into the SRiF issues?

I am not trying to stir up issues just not sure why nothing was mentioned about the new GPS internal parts change and the issues related to that.

I don't typically include GPS chipsets within reviews. In many cases, companies won't provide that information. Sometimes it can be found in FCC filings, but not always. And breaking apart a unit when none others are available seems like a review-limiting move. I do plan at some point to start doing tear-downs, but right now just have too much on my plate to do that (since it would involve getting/finding chipset people that were unbiased in the industry and willing to help identify parts).

As for why I didn't mention GPS issues, again, because I didn't see any (and still don't see any, and I've had access to three different Fenix2 units at this point). I saw many other earlier issues when I noted in the review, but GPS accuracy wasn't one of them.

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My tiny little slice of the internets: dcrainmaker.com

FWIW, my 220 has seemingly been pretty spot on since receiving it a couple weeks ago. I'm heading off on a "training" weekend with some mates so it will be interesting to see how it aligns with their devices.

My fiancé has the 220 and the same issues. I wore it with my 910 and the paces/distances were always way off. Even after sending it back and doing all the updates it still continues to be an issue.

I bought the 220 when it came out, informed entirely by DCR's review. I experienced no accuracy issues relative to the 305 - my frame of reference. After a few months I decided some of the 620 features mattered (and again trusted DCR's insights) so I upgraded and have had no issues with accuracy. Like my iphone, it's become thoughtless tech to me - as in, I don't need to think about it. It does the job I ask it to do flawlessly so far.

I think DCR is right - it's important to use the device in your real world to determine its value to you.

PS - DCR, yours is an important voice in athletic technology. Where consumer electronics has countless blogs and review sites, you stand out for knowing your shit, not parroting PR material, and keeping everybody honest. Thanks.

 
>I'm 100% in agreement with rbuike on this one. Getting accurate OWS GPS with a watch on your wrist is a crapshoot, your arm is underwater most of the time, unable to get a GPS signal and dependent on the brief time >your arm is above water to get a signal. Depending on your swim style, stroke rate, etc., accuracy is going to vary widely person to person.

That's more an argument about whether you get better data from wearing a GPS on your wrist vs. in your cap. There's little question that the cap is better.

But the point is that most GPS units do far more than just the basic, static calculation of position from GPS signals. They have internal filters (e.g. Kalman filter) that model the type of motion taking place and do predictive estimation in the periods with degraded signal, or no signal. They model velocity, heading, etc. For example a motion model for a swimmer would employ the constraints of swimming motion to limit error. Swimmers are slow. So if the raw GPS calculation showed a 3m jump in one second, the filter would weight that sample very lightly, and trust the "extrapolation" from prior data more.

So if you want to test how well a GPS works for swimming with a GPS on your wrist, then the best way is to test it while swimming with the GPS on your wrist.

If you want to test how well it does with the GPS in your cap, test it with the GPS in your cap.