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…:-)

- 5 comments by 2 or more people Not publicly viewable

  1. Jason Jacobs

    Hi Steve,
    I am Jason, the founder of the company behind RunKeeper. Thanks for writing about us! One suggestion for you. If you have not tried already, go to the RunKeeper settings and try turning the GPS filter to ‘none’. In areas of poor coverage, this can improve your results. Also, we have seen big improvements in the GPS reliability in Apple’s last OS update, and we expect it will continue to improve and become more consistent in all conditions over time.

    If you have any questions/feedback/etc. you can always reach me at


    08 Dec 2008, 14:39

  2. Steve Rumsby

    I found that setting after today’s ride, and it was on “High”. I’ve dropped it to “Medium” and we’ll see if that works any better. I noticed on your forum that some people had the opposite problem – too much GPS noise – so I’m reluctant to turn it down too far. I’ll play…

    08 Dec 2008, 14:56

  3. Jon Werner

    Steve, we have been reluctant to release a version of our award winning service on the iPhone for just this reason. Once you get a bad reading you start to question all the other stats as well. Our current testing and observations do not leave us with a comfortable feeling for rolling out a service that meets our high quality requirements of accuracy within +/- 2%. While we released our first version of the product only for the US back in 2006, there is a version for the blackberry that is available world wide for the Curve and 8800 series that includes GPS. We also have an N95 version lurking around as well. If you were stateside, there are over 60 other phone models our software runs on with +/- 2% accuracy.


    09 Dec 2008, 16:41

  4. A friend mentioned that the GPS function on the Nokia N95 is way better that that on the iPhone. However, you have to make sure you have the latest latest firmware version and the new Maploader.

    11 Dec 2008, 12:33

  5. OneToRemember

    I thought that the following post might be interesting. We have also found that it is good to turn the iPhone on and off before you use the App – it seems to work and you get fewer squiggles.

    We spent some time during the summer developing a new iPhone App called iFootpath Mobile. It has a GPS tracker which records and you can upload the track to our website for editing. We have used it a lot now and it is working well.

    We reviewed other Apps too to see what they offer. Although they all have similar functions they are built for different uses. For example some are for walkers, joggers and those using a bike. Some are for meeting friends on a walk and some …... well to be honest we didn’t really figure it out. Viewranger looks to have the most features and probably the biggest fan base.

    We have built ours so that walkers can navigate along detailed route descriptions with pictures and of course a map – all are available on the iPhone – or you can print them from the website. We hope that it will find some fans. Although we hope to appeal to serious walkers we also want to attract the casual walker that likes to explore highways and byways, river walks, etc.

    iFootpath Mobile – as we call the App -also allows walks to be tracked and uploaded to our site. You can then download them and upload them to other sites if you wish. On the website we have added a GPX file editor. It allows you to trim, edit and add waypoints and then save. we have noticed that sometimes the track can go a bit wiggly. With the editor you can get rid of the squiggles. You can use the GPX editor on the website even if you don’t use our App as you can upload directly. (You will have to register which is easy and quick)

    So we are every pleased with our App and hope that some of you may give it a spin. Here is a link if you want to look closer at the features.[/u]

    The website has some detailed user guides for the App and GPX/GPS editor.

    24 Sep 2011, 09:24

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