All 6 entries tagged Gps

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December 08, 2008

iPhone GPS reliability

There are several fitness-related apps out there now for the iPhone that record running, cycling or other activities and sync them to a website where you can do further analysis, get monthly totals, etc. GPS Tracker, Trailguru and RunKeeper are three such apps I’ve played with recently while out cycling. I like to record every cycle journey and calculate statistics about them, and so these apps should be perfect for me.

The problem is, I can’t rely on them. My cycle computer records every journey consistently. Over the same route I get the same distance recorded, to within a hundredth of a mile, every single time. Every. Single. Time. A GPS track seems to vary in length a little more than that, but not enough to be too much of a problem. The problem is, I don’t always get a complete GPS track recorded. The iPhone seems to loose satellite lock too easily. Take today’s route as an example:

The straight line from Balsall Common to Burton Green should follow the road, but doesn’t. Instead it leaps straight from the A452 to Cromwell Lane for a little while before leaping again straight to University House. There’s not a lot of tree cover on those roads. Less that at other points on the route. Based on my experiments so far, this sort of thing happens on about 25% of my rides. For my purposes, that’s just useless. I carry the phone in the back pocket of my cycling jacket so it should have a reasonable view of the sky.

All the apps I’ve tried do this occasionally, so it seems it has to be the hardware. I’ve also got a fairly basic Garmin handheld GPSr (a Geko 201) that has never done this on a cycle ride. It does lose satellite lock when walking in woods, but on the roads it never does. Does the Garmin have better a GPS receiver than the iPhone. I thought not, but the evidence says otherwise.

As much as I’d love to record every cycle route this way, there’s just no point if it is going to be so unreliable. Sigh…

Addendum: I don’t remember any such problems when using SportsTracker on Nokia devices, over some of the same routes even. Indeed the Nokia E71 I had on trial a little while ago managed to correctly record the whole of the 68 mile MacRide I did back in September. Not a glitch. Maybe I should be hoping that Nokia manage to come up with an iPhone-killer by the time my iPhone contract is up? Christmas 2009 would be perfect timing…:-)


September 29, 2008

An iPhone compatible alternative to SportsTracker

Follow-up to Sportstracker revisited from Steve's blog

This morning I discovered an iPhone app called “TrailGuru”, along with a corresponding website. It does much of what SprtsTracker does, and more. The iPhone app records a track as you are walking/running/cycling/whatever and uploads it to the website. The app gives you just basic information – distance, time, max speed, etc., unlike the Nokia SportsTracker app which generates pretty graphs and stuff on the phone. You have to go to the TrailGuru website to get the extra analysis. My lunchtime ride is here.

An improvement on SportsTracker, though, is that it keeps cumulative statistics, so if you record and upload every route you’ll get nice pretty graphs with monthly distance, duration, etc. This is much more useful. There’s more analysis it could do once there’s more data in there (year-on-year comparisons), and some other data it could hold against the rides (cadence and heart-rate data, for example), but it is pretty good as it is.

There is a problem with the recording process, though. The “moving time” it records is longer than the moving time recorded by my cycle computer. By quite a lot – over 2 minutes during my 52 minute ride today. I know my cycle computer is pretty much spot on, so it seems the GPS software is taking its time noticing that I’ve stopped. Hopefully they’ll fix this soon, unless it is Apple’s fault in which case it will take years to sort out!!

Still, if you have an iPhone and regularly run or cycle, this is definitely worth a look…


September 17, 2008

Sportstracker revisited

Follow-up to Nokia N82 – GPS stuff from Steve's blog

Back in January I wrote about Nokia’s SportsTracker, which is a phone-based application that uses GPS to record a “workout” including the route itself and various other stats, and then provides a set of mostly useful reports and pretty graphs. Since SportsTracker is on the E71 I got a couple of weeks ago I thought I’d try it again, and in particular I recorded my MacRide cycle a couple of weekends ago.

The end result is here. There’s no easily embeddable version, but you can wrap it in a simple iframe:

The workout profile is interesting, and you can clearly see Bakers Hill in the Cotswolds, about 45 miles into the route, where I had to get off and push because the hill was so steep. Oddly, you get more graphs in the phone version of the app than on the web version, which is a bit surprising.

It seems like not a lot has been done to this since I last tried it. I would really want cumulative distance and time figures to support my quest for annual totals. Those should be easy to do. A moving average speed would be good too. On the plus side, last time, I complained that you couldn’t import GPS tracks from other devices. You can now, as well as creating them manually by clicking on a map. That’s good.

Overall, this is still interesting, but not interesting enough for my purposes. I need to record every route and have cumulative statistics, like I currently get from MyCyclingLog. SportsTracker could be really good, but it isn’t yet. And given some of Nokia’s current focus on community services, the community functionality in SportsTracker is somewhat lacking too. I’d expect groups and friends in there somehow.


March 25, 2008

Finding the shortest route…

As I was driving down the M6 yesterday evening there was an accident that caused a bit of a hold-up. Not knowing how long this was going to take, I hit the “detour” button on the SatNav to see if there was a convenient way around the blockage. Oddly, after finding an alternative route, the SatNav’s ETA was earlier than previously, even though I have it set to plot the quickest route. If the detour was quicker, why wasn’t it sending me that way in the first place?

It turns out this is a variation of the Travelling Salesman Problem, which is hard to solve both accurately and quickly. I guess the SatNav is using an algorithm that gets close to, but not always exactly, the shortest route. To be fair, the difference was only a couple of minutes. I was just surprised, until I thought about it a bit more…


January 03, 2008

Nokia N82 – GPS stuff

Follow-up to Nokia N82 from Steve's blog

The Nokia N82 has a GPS receiver built in. It comes with a typical SatNav application that shows you where you are, does route finding, has a Points of Interest database, etc. The usual stuff. There are a couple of differences from a regular SatNav, though:
  1. The route finding is only visual by default. You have to pay extra for a voice-prompt service, on a subscription basis I believe. I’m not sure I like that model much. As an in-car navigational aid it is pretty useless without voice prompts. To navigate on foot, though, in a strange city, it is perfect. Having such a facility always on your person “just in case” would be really useful. However, see below…
  2. The maps are downloadable. The phone comes with very little, and when you browse to a new location it downloads the maps it needs. It can do this over WiFi, which is good because the maps are going to be quite large and it would be expensive to ship them over GPRS (or 3G?). So, if you know you are going somewhere, you’ll want to browse there in advance to make sure you’ve got the maps. If you don’t know you’ll need it until you find yourself lost, then I’m afraid you’re stuck with downloading a few MB of maps. It seems to download in smallish chunks, which is either good or bad depending on your point of view. I’ve just gone browsing around Manchester, which I’ve never looked at before, and pulled down about 2MB of data. On the plus side, I guess this means you can get map updates for free…?

One interesting point is that the N82 managed to get a satellite lock while I was playing with it at home. That’s the only time I’ve ever had a GPS device find satellites while indoors. I was sitting near a window at the time, but still nothing else I’ve tried (Garmin handheld and SatNav devices) has done so well.

So, basic SatNav functionality works as you’d expect, but with a couple of potentially irritating quirks.

Now to the main reason I was sent this phone in the first place – Sports Tracker. This came pre-installed on the phone I was sent, but it is freely downloadable. It works with any phone with built-in GPS, and also with bluetooth GPS receivers. There’s a list of compatible devices on the website.

Sports Tracker uses the GPS receiver to record what it calls “workouts”. Basically this is what regular GPS receivers would call a tracklog. From this is calculates a bunch of statistics – max/min/ave speed, etc. and produces pretty graphs of speed against altitude and similar. All of this is done on the phone itself, which is quite neat. Additionally, it is linked to a web service and will upload the information to the web where you can add comments and share route. For example, here is my lunchtime cycle from yesterday. You can see the usual stats, plus the route overlaid on Google Maps so others can scroll around it and see where you went. You can download a KML file too, so you can put it in a GPS receiver to follow. I haven’t been able to find a way to import a route into Sports Tracker itself though, to allow me to follow somebody else’s route. That seems a bit of an oversight.

Then again, I’m not sure how well the device would work mounted on the handlebars. I don’t have a handlebar mount for it so I can’t be sure. Would it survive the vibration? It isn’t waterproof, so it wouldn’t survive being rained on. I’m not sure the phone is really designed for that sort of use. I’ve been carrying it in the back pocket of my jersey. But that could get it quite damp on a long/hard ride.

I like Sports Tracker. It combines a lot of the stuff I’ve tried to do on this blog – cycling stats, route maps, etc. – in a way that’s quite easy to use. There’s quite a lot of stuff missing though. I need cumulative statistics – miles per month/year, average speed per month/year, etc. If I could just record every journey with Sports Tracker, upload it to the web site, and have everything I need calculated for me (it has the necessary data after all) that would be great. But I’m going to have to record everything elsewhere too. Nokia could do worse that look at My Cycling Log for inspiration.

Overall, then, Sports Tracker is a good start but it needs more work, not on the phone-based app but on the companion web site. The phone itself would probably work well enough for running/walking activities, but I’m not sure how useful it is as a cycling aid. It doesn’t seem rugged enough. I’d be worried about shaking it to bits if it was handlebar mounted.


October 16, 2006

Google Maps API

Writing about web page http://erasmoperez.blogspot.com/2006/10/za-xochicalco-cuernavaca-morelos-081006.html

It would be really nice to be able to do this sort of thing on Warwick Blogs, and do away with my static photoshopped route maps. Any chance, guys?


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