5 ms·
As an avid hiker and runner I'm more excited to see what this will do for things like Garmin smart watches. I run through downtown Boston a few times a week an
by colinwilson 9y ago
As an avid hiker and runner I'm more excited to see what this will do for things like Garmin smart watches. I run through downtown Boston a few times a week and the accuracy is very bad at times making you look like you run much farther than you do.
- foota 9y agoYou could probably trade accuracy of route position for accuracy of distance by averaging samples.
- colinwilson 9y agoYou can see how off the trace can be here: https://i.imgur.com/eHJI8FH.jpg https://i.imgur.com/eHJI8FH.jpg . You could probably do some smoothing to help fit some of this to a street but I've been on runs where I zig zag down streets just to add distance or to do hills.
- semi-extrinsic 9y agoWow, that's pretty horrible, must be giving you close to twice the actual distance. I think Google Maps on my phone applies some smoothing that does this a lot better, but then it can lag for a while when I'm going sharp right in an intersection. Maybe try telling it that you're biking instead, my guess is they do more smoothing the higher speed they expect.
- jtolmar 9y agoIt's pretty much raw GPS if you're in walking or biking mode. Driving mode uses sophisticated filtering algorithms, and doesn't actually make any assumptions about your speed, though it does assume you're on a road.
- dionidium 9y agoHere's a look at some of my biking in Midtown Manhattan (iPhone 7 / Strava). It's pretty much garbage. https://imgur.com/mJFFKoV https://imgur.com/mJFFKoV https://imgur.com/RYuYrcI https://imgur.com/RYuYrcI
- jtolmar 9y agoI've been working on GPS filtering for three years and that's bad even by my standards. Chips with L5 should do a lot to clear that up though.
- cantagi 9y agoI have a question for you. If GPS locations in cities are affected by reflections off buildings, wouldn't the effect be deterministic and could you take advantage of that to reduce the noise?
- eatbitseveryday 9y agoDo you run the same path frequently? When I do, I keep the path the same, as I pre-calculate the distance, and can keep a watch to track my time. Thus I have no need for path tracking. A GPS unit is useful for assisting dynamically changing routes (e.g. driving) or to track unknown paths (e.g. plotting your hike in snow/darkness). May I ask what you'd need a fine-accuracy GPS unit for during a run?
- colinwilson 9y agoFor runs it's mostly just for fun. I use Strava so it has sections they identify along your run that they rank you against your friends and strangers. I do end up running very similar routes most of the time. I mostly find the GPS invaluable in hiking. It can be a great thing to have on the top of a mountain in the winter with low visibility. If you get up to a summit and the weather turns, you can have the watch send you back down the way you came. Nice and safe.
- rossriley 9y agoThe only deficiency I find is accuracy when you are trying to workout at a specific pace on track. On a longer run they are probably accurate to within 1% which makes practically no difference but you often find on a track that the inaccuracy multiplies on each lap so if you are doing say 1 mile repeats (4 laps) then by the end of the mile you can be 20 metres out. It's not a biggie because visually you can see if your watch says 0.23, 0.46 etc as you go past the 402m mark you know that you need to up your pace because it's short but having a more precise distance and therefore pace would save a few brain cells when you're trying to concentrate on hitting your paces.
- nradov 9y agoI try to run different paths as much as possible. My Garmin Forerunner fitness tracker is reasonably accurate at recording the path and displaying an instantaneous pace, but it still jumps around and gives erratic results at times. So better accuracy would certainly be a welcome improvement.
- cozzyd 9y agoThe multipath in urban environments probably limits the accuracy, unfortunately.
- pacificmint 9y agoThe article actually covers that. With the existing L1 signal the multipath signals overlap each other and its hard to find out which the original signal was. The newer L5 signal is much shorter, so multipath signals will show up as individual peaks, and the receiver can simply pick the first signal, cause that will be the direct one.
- forapurpose 9y ago> accuracy is very bad at times What makes anyone confident in the accuracy of wearable tracking devices? I haven't seen it verified and I wouldn't assume it: Accuracy is expensive, generally speaking, and few consumers will pay for it or even question it - how often have you heard someone mention it? Or, for example, have you wondered how accurate your simple bathroom scale is? I looked into it a little, wanting to collect accurate health data: IIRC +/- 0.1 kg (~0.2 lbs) is available in <$100 scales, but for real precision you need the $500 scales at your doctor's office. And how consistent is it? I tested mine, a decent one with good reviews, and getting it to report the same weight in immediately consecutive measurements was a challenge; I had to stand on it in just the right way. Here are a couple articles that found the accuracy of activity trackers wanting. I've seen other articles in places like ZDnet that found the same problems, though based on less rigorous research. Accuracy of Smartphone Applications and Wearable Devices for Tracking Physical Activity Data in JAMA <https://jamanetwork.com/journals/jama/fullarticle/2108876> https://jamanetwork.com/journals/jama/fullarticle/2108876> Accuracy Of Fitbit Data Seriously Questioned By New Study <https://www.sporttechie.com/accuracy-of-fitbit-data-seriously-questioned-by-new-study/> https://www.sporttechie.com/accuracy-of-fitbit-data-seriousl... (Sorry if this disrupts your confidence in your data!)
- jordanthoms 9y agoI'm not sure what the value of a more accurate scale would be for a bathroom scale - your weight varies by far more than 100g just based on what you've eaten and how much water you've retained.
- Moru 9y agoA guess: Two uncertain data points makes it even worse. If you can at least depend on the scale, the error is lower. I tested our old Nintendo wii (or whatever it's called) balance board and so far it gives the same value every time I step on it. The value was also only 0.2 kg off from the doctors expensive scale.
- forapurpose 9y ago> your weight varies by far more than 100g just based on what you've eaten and how much water you've retained. Yeah, I noticed. Does anyone know how this data is normalized by professional researchers?
- the7nd 9y agoIf you are interested in improved speed & distance tracking, take a look at this: http://fellrnr.com/wiki/GPS_Accuracy http://fellrnr.com/wiki/GPS_Accuracy There are some foot pods that will outperform GPS.
- as-j 9y agoThey don’t in real running. After seeing his page I got super excited. They’re really accurate at the pace you csalibrate them too, then drift quickly once that pace changes. So if you camlivrat them at 7:30min/mile, then run 8min/mile they’re pretty far off. Especially if you’re a distance running, or looking for accurate pacing. I’ve tested it both on marathons and tracks. All current running watches and phone software uses single point calibrations. Now if they curved fit 2 or 3 points....
- the7nd 9y agoStryd is a calibration-free technology. Motion capture technology is used to precisely track the movement of the foot at different running speeds & on different terrains.
- drdrey 9y agoIt also has the potential to greatly increase the accuracy of the instant pace, which is a lot more volatile than the total distance
- unfamiliar 9y agoI mean, how erratically are you running? My pace wouldn't vary much over a typical 200m.
- megablast 9y agoStopping at damn traffic lights and constantly waiting for cars.
- drdrey 9y agoThat's my point, even if you run at a steady pace the instant pace reported by your device tends to jump around quite a bit, even if they smooth it out over 10s. On my Garmin watch, the instant pace typically jumps around by +-20s/mile, which is significant when you're trying to hit a specific pace target.
- ceejayoz 9y agoI've run into a severe issue with Fitbit's app on the iPhone 7. On my older iPhone, the mile counts were reasonably accurate. On the 7, there's a spurious ~2 miles per hour added at all times. My guess is that the 7's chip updates position much more frequently, so that small inaccuracies (a couple dozen feet west, then a couple dozen feet east on the next update) make it look like I'm sprinting all over the place in random directions at high speed. No idea why Fitbit doesn't smooth it out a little... Did a six hour, 4.6 mile hike in the Adirondacks and it tracked me at 18 miles (edit: 13, sorry).
- brlewis 9y agoWere you using only the phone and not a Fitbit tracker? If so it's only going off steps, not GPS. https://help.fitbit.com/articles/en_US/Help_article/1875#MonitorDistance https://help.fitbit.com/articles/en_US/Help_article/1875#Mon... If the terrain forced you to take a lot of shorter steps then that explains it. In 6 hours of normal steps you'd expect to walk about 18 miles.
- ceejayoz 9y agoThe Fitbit app lets you take a GPS track using the phone's GPS (as the Charge HR doesn't have a GPS chip). It's not step-based. Standing still for a break still makes my mileage go up, and I can see the blue dot on the map in the Fitbit app jitter around a little - a few feet here, a few feet there. Here's an example of the generated map: https://imgur.com/a/yoqei https://imgur.com/a/yoqei (That's a ~5 mile hike in actual mileage - and you can see the issue very clearly between "miles" 4 and 5 on the map, where we likely took a long break, and in the longer distance between the downhill miles as we were moving faster)