Amazingly thorough analysis of GPS accuracy
davemunger
Posts: 1,139 Member
Super thorough breakdown of many of the major devices.
http://fellrnr.com/wiki/GPS_Accuracy
TL/DR: Garmin 910xt rules, Garmin 620 drools.
http://fellrnr.com/wiki/GPS_Accuracy
TL/DR: Garmin 910xt rules, Garmin 620 drools.
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Thanks Dave,
I was thinking that the apps worked fine for me but in the last week they have been failing miserably. I ran today using map my run and runtastic. Distances were off by over a mile on one and 1/2 mile on the other (a route I have taken many times before), and runtastic had me running my first mile at 6:30 minute pace, apparently while jumping large buildings all the while.
I wonder if it isn't the apps, and if one of the satellites is off kilter--- but my car gps seems to be fine.
Anybody else having GPS issues in the past week?0 -
Cloudy / stormy weather does seem to affect them but I haven't been having any particular issues this week (including the rainy day).0
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^^^... I know about those cloud covers as well as if you are running on a trail with tree cover. My GPS had me running 18 minute miles...0
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Thanks Dave,
I was thinking that the apps worked fine for me but in the last week they have been failing miserably. I ran today using map my run and runtastic. Distances were off by over a mile on one and 1/2 mile on the other (a route I have taken many times before), and runtastic had me running my first mile at 6:30 minute pace, apparently while jumping large buildings all the while.
I wonder if it isn't the apps, and if one of the satellites is off kilter--- but my car gps seems to be fine.
Anybody else having GPS issues in the past week?
If the GPS system was having issues, LOTS of things wouldn't be working correctly. My impression (I've read a lot about the system over the years) is that the error, in the system, is in the range of a few inches. We civilians have a signal that's good to a few feet but the military signal is even more accurate.0 -
Super thorough breakdown of many of the major devices.
http://fellrnr.com/wiki/GPS_Accuracy
TL/DR: Garmin 910xt rules, Garmin 620 drools.
Well fiddlesticks. I have the 620 on my Amazon wish list! The 910xt may be the way to go. Prolly better for ultras because of better battery life as well. My 305 dies at about the 8 hour mark.0 -
Thank you so much for posting this .... that was so very nice of you. Truly Appreciated.0
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I am going to guess that Fellrnr is a triathlete based on mostly testing tri-centric watches (310/610/620/910). I only point this out as the two watches I am currently looking at (210/220) are not included. I suspect that they would have simlar performance to the 6xx versions but I would hate to be wrong on something that I plan to use for several years after purchasing.0
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I am going to guess that Fellrnr is a triathlete based on mostly testing tri-centric watches (310/610/620/910). I only point this out as the two watches I am currently looking at (210/220) are not included. I suspect that they would have simlar performance to the 6xx versions but I would hate to be wrong on something that I plan to use for several years after purchasing.
He is an ultrarunner and does a lot of 100-mile or 24-hour runs. Very few running-only watches last that long.0 -
Ugh I went through 3 910XTs - all were glitchy and shut off during runs. I loved the watch, but am very leery about it. Glad it works for you though.0
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Ugh I went through 3 910XTs - all were glitchy and shut off during runs. I loved the watch, but am very leery about it. Glad it works for you though.
That's a big problem with this data. Individual units have tremendous variance. I know people with 620s that work great, and I've heard similar issues with 910xts. Mine works great, and I have several friends who love their 910s.
The one unit that I've heard *very* few complaints about (and appears to be one of the best in Fellrnr's study as well) is the 310xt.0 -
Oh, the irony! THE IRONY! I literally just got my FR 10 in the mail yesterday.
BUT, the deal for me is that I wanted the most basic of Garmin models and am looking only for horseshoe/hand grenade type of accuracy. It's a huge improvement from my past marathon training which entailed a 20 dollar Timex IM watch from Target.
I am happy to know though that the 310XT I bought for my husband last year is a consistent performer! And more importantly, it's been working great for him through all the miles he's logged, so there you go. 0 -
Love this! WIll have to read carefully later.0
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Very interesting read, thanks for that Dave.
I'll try to defend the Garmin 620 here. I've had both the 610 and the 620. When I first got the 620, I ran with both the 610, 620, as well as an iPhone 4s on the same few runs.
Both the 610 and 620 were were within 0.03M over the course of 6.25M. The 4S overestimated by about 0.1M.
I thought the accuracy was pretty close between them so I never did any more in-depth analysis.0 -
the 910xt, which I got to replace a 310xt that died a slow, frustrating death. The 310 was awesome for about 3 years and just went bad...slowly. By the time I'd purchased a couple of different HRM straps and a new HR receiver, I should have just gotten a new unit (I was able to sell the new receiver, so not much of a loss there). Sure, I could have sent it back to Garmin to have them work it over, but I decided it was time to upgrade. And so far I've found that the battery lasts longer than what they advertise. I've gotten as much as 30 hours out of it.
Also, the 910 has a barometric altimeter. While the 310 was pretty good with the elevation correction, the 910 is superior in tracking elev gain/loss accurately, by far.
I use my 310 as a bike computer now :-)0 -
I have been using my 610 since January with hardly a complaint compared to previously using Runtastic only to find that it had dropped the signal and not picked it up again until later on in my run.
The only issue I have had with my 610 is on one clear blue day it recorded my elevation gain at 1,450 ft. May not seem like a big deal, but I live in the prairies, and the "hill" that I went up is the same (and only hill) on the marathon course I'm running in June, and I believe they mention it in their course description of a maximum elevation change of 10 ft. But, everything else seemed to be on with a small margin of error.0 -
the 910xt, which I got to replace a 310xt that died a slow, frustrating death. The 310 was awesome for about 3 years and just went bad...slowly. By the time I'd purchased a couple of different HRM straps and a new HR receiver, I should have just gotten a new unit (I was able to sell the new receiver, so not much of a loss there). Sure, I could have sent it back to Garmin to have them work it over, but I decided it was time to upgrade. And so far I've found that the battery lasts longer than what they advertise. I've gotten as much as 30 hours out of it.
Also, the 910 has a barometric altimeter. While the 310 was pretty good with the elevation correction, the 910 is superior in tracking elev gain/loss accurately, by far.
I use my 310 as a bike computer now :-)
I have a 305 and the way I get accurate elevation correction is to cheat. I use Sporttracks software and there is an elevation correction plugin that does it based upon elevation map data. That doesn't help what I upload elsewhere, but that doesn't really matter when I have the software to slice and dice to my hearts content. It's really silly to think about how many places I load my data at least in part: Excel, Sporttracks, Runkeeper, MFP, Strava, GarminConnect, Fitocracy and log it even in Facebook. I know people who talk about the joy of not even wearing a watch and just enjoy the run, but then I think about how I will miss that days worth of precious data. I'm sick I tell you! 
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the 910xt, which I got to replace a 310xt that died a slow, frustrating death. The 310 was awesome for about 3 years and just went bad...slowly. By the time I'd purchased a couple of different HRM straps and a new HR receiver, I should have just gotten a new unit (I was able to sell the new receiver, so not much of a loss there). Sure, I could have sent it back to Garmin to have them work it over, but I decided it was time to upgrade. And so far I've found that the battery lasts longer than what they advertise. I've gotten as much as 30 hours out of it.
Also, the 910 has a barometric altimeter. While the 310 was pretty good with the elevation correction, the 910 is superior in tracking elev gain/loss accurately, by far.
I use my 310 as a bike computer now :-)
I have a 305 and the way I get accurate elevation correction is to cheat. I use Sporttracks software and there is an elevation correction plugin that does it based upon elevation map data. That doesn't help what I upload elsewhere, but that doesn't really matter when I have the software to slice and dice to my hearts content. It's really silly to think about how many places I load my data at least in part: Excel, Sporttracks, Runkeeper, MFP, Strava, GarminConnect, Fitocracy and log it even in Facebook. I know people who talk about the joy of not even wearing a watch and just enjoy the run, but then I think about how I will miss that days worth of precious data. I'm sick I tell you! )
I upload to RunningAhead.com and it replaces the elevation data with Google maps elevation data.0 -
I have a 305 and the way I get accurate elevation correction is to cheat. I use Sporttracks software and there is an elevation correction plugin that does it based upon elevation map data. That doesn't help what I upload elsewhere, but that doesn't really matter when I have the software to slice and dice to my hearts content. It's really silly to think about how many places I load my data at least in part: Excel, Sporttracks, Runkeeper, MFP, Strava, GarminConnect, Fitocracy and log it even in Facebook. I know people who talk about the joy of not even wearing a watch and just enjoy the run, but then I think about how I will miss that days worth of precious data. I'm sick I tell you! )
I've noticed most of this elevation correction stuff can introduce errors. Not a huge deal but it's nice to be able to compare to the barometric elevation. Bridges really throw off the elevation correction because maps measure the elevation of the river underneath, not the elevation of the bridge.0 -
I have a 305 and the way I get accurate elevation correction is to cheat. I use Sporttracks software and there is an elevation correction plugin that does it based upon elevation map data. That doesn't help what I upload elsewhere, but that doesn't really matter when I have the software to slice and dice to my hearts content. It's really silly to think about how many places I load my data at least in part: Excel, Sporttracks, Runkeeper, MFP, Strava, GarminConnect, Fitocracy and log it even in Facebook. I know people who talk about the joy of not even wearing a watch and just enjoy the run, but then I think about how I will miss that days worth of precious data. I'm sick I tell you! )
I've noticed most of this elevation correction stuff can introduce errors. Not a huge deal but it's nice to be able to compare to the barometric elevation. Bridges really throw off the elevation correction because maps measure the elevation of the river underneath, not the elevation of the bridge.
I noticed this when I looked at the elevation map for a 10K here that goes over the Bay Bridge. The chart showed it was all downhill to the middle and then uphill the rest of the way. Completely the opposite of how it should have looked! 0 -
Thanks for the info. I hope to be making a purchase in the next couple of months.0
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Feeling sorry for my poor little F10 now! I got it when I just started running and it's seen me through 4 halfs and a ton of smaller runs...with a marathon this fall maybe I do need to upgrade. Blech!0
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iphone seems to slot in there pretty nicely. So thats good. 0
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I'm still rocking a Garmin 201 Forerunner from 2003. It matches my classic addidas shorts (kidding). It does gap on trails (not the shorts), but so do a lot of Garmins. I cant upload anything from it because I don't think that technology was available then, but with the times I'm throwing down, probably for the better. It DOES display time, distance and pace all on one screen and that's harder to find in Garmin now unless you are dropping $300 + and I just cant do it yet.0
