Non-motoring > iPhone & GPS Miscellaneous
Thread Author: Rudedog Replies: 15
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New Mon 3 Jun 13 16:53 
 iPhone & GPS - Rudedog
I've been using an iPhone app that lets me record by cycle rides (time/distance/route), but the last couple have resulted in route maps that are wildly off from the actual route. So is the iPhone a true GPS device like a satnav? I'm sure my Tom-Tom would have been ok, it's just annoying because half way around my loop it seems a warning that 'GPS had been lost' came up the phone's screen but of course unless you stop to look at it you wouldn't know. Or, as I suspect, is it using the mobile network to work out my position in which case I can sort of understand some of the problems in the high banked narrow lanes but my route start is out in the open where I get a strong 3G signal.

I forgot to mention that the app I'm using is called Strava, can anybody recommended any of the other cycle apps out there that might give me a better result or will they all roughly be the same?
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New Mon 3 Jun 13 17:59 
 iPhone & GPS - No FM2R
3G location is accurate enough for a weather forecast and little else. You need to be using GPS.

I suspect, although I don't know, that the iPhone is switching GPS off when it sleeps.
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New Mon 3 Jun 13 18:05 
 iPhone & GPS - rtj70
I suspect GPS is being switched off - perhaps when the screen is off? To save power you might have it set like that. Not having an iphone to look at, this is just a guess. But I know there's plenty of settings on an Android phone to save power including how GPS is handled and turned off etc.
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New Mon 3 Jun 13 18:06 
 iPhone & GPS - Zero
Its loosing the GPS because it cant see the satellites. I would guess in the same location(s) the tom-tom would whine as well. Most sat nav apps wont use 3G triangulation, just give up on the routing when the GPS is lost.

An app that uses GPS wont let it go when the main phone "sleeps" GPS remains on in the background. Had apps run the battery down like that.
Last edited by: Zero on Mon 3 Jun 13 at 18:08
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New Mon 3 Jun 13 18:12 
 iPhone & GPS - No FM2R
>>An app that uses GPS wont let it go when the main phone "sleeps" GPS remains on in the background.

I think it must be configurable because my wife's iPhone loses itself using maps when it sleeps, and I'm sure that is because its turning the GPS off.
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New Mon 3 Jun 13 18:14 
 iPhone & GPS - Zero
probably depends n the app, I have a couple where its not configurable. You have to set the whole app not to run in the background. Pointless when mapping.
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New Mon 3 Jun 13 18:20 
 iPhone & GPS - rtj70
I'd be surprised if a modern smartphone can't keep a GPS lock. My Android phone (which also uses the GLONASS satellites) can have a lock on 10 or more satellites when sat indoors. So putting this in a pocket shouldn't make a difference.

But maybe this is something to do with the Rudedog is putting the phone whilst out riding?
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New Mon 3 Jun 13 18:23 
 iPhone & GPS - No FM2R
However, mapping on a phone is at best a compromise. If you're serious about it then the phone is probably not the way to go.
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New Mon 3 Jun 13 18:33 
 iPhone & GPS - Zero
Not the case in my experience., I have an excellent mapping app on the iphone, good enough for general hiking.

Iphones are useless as a car sat nav tho, due to human factors.
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New Mon 3 Jun 13 18:51 
 iPhone & GPS - No FM2R
To be fair I only use Sat Nav in a car so I wouldn't know about cycling or hiking.
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New Mon 3 Jun 13 19:41 
 iPhone & GPS - Rudedog
OK so the iPhone does have a built in GPS locator, in that case why don't I have to update the satellite positions like I do on my TT? if I don't do that it can take ages to start mapping after start up in the car. I'll check that I didn't start off before it achieved some-kind of sat-lock although the GPS indicator had all of the green bars lit up.

Maybe I'll give feedback saying that if a warning of 'GPS signal lost' is displayed then the phone should vibrate as well to bring attention to it (I keep mine is in my back vest pocket).
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New Mon 3 Jun 13 20:20 
 iPhone & GPS - BobbyG
Rudedog, I use Sports Tracker - am very happy with it although I use it on android but is available for iphone as well I'm sure.
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New Mon 3 Jun 13 21:41 
 iPhone & GPS - Rudedog
Thanks I'll have a look at it, in theory I could run both at the same time and compare the two results.
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New Tue 4 Jun 13 17:35 
 iPhone & GPS - borasport
MapMy....(ride/walk/run/fitness) work for me, and it's available on Iphone and android
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New Tue 4 Jun 13 19:31 
 iPhone & GPS - Rudedog
Now I've done a bit of reading about the GPS, it seems that it's quite a common problem across several apps. Apparently the iPhone uses AGPS to get started and then the GPS proper kicks in once it has achieved full GPS lock, interestingly I did my regular route today in my car with the phone on the centre armrest and even at 30-40 mph the route was clear and correct whereas on my bike the trace would suddenly jump sideways off into a field or become very spiky maybe it has something to do with me travelling at a far slower speed or how often the software takes a positioning point.
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New Tue 4 Jun 13 19:59 
 iPhone & GPS - rtj70
>> iPhone uses AGPS to get started

Any smartphone with GPS will use assisted GPS to start with. You perhaps don't know why.

To figure out where you are the GPS receiver needs to know where the satellites are. This data is called ephemeris data. It can take a bit of time to download this via the GPS satellites. A quicker solution for data enabled devices was to download this ephemeris data via the data network.

So maybe you're not referring to AGPS after all? Maybe you're referring to smartphones' ability to work out roughly where they are (quite accurate at times) using other means including wifi signals and mobile phone masts.


>> whereas on my bike the trace would suddenly jump sideways off into a field or become
>> very spiky maybe it has something to do with me travelling at a far slower speed

If the phone had line of site of the sky (and not trees/foliage) etc. then walking or on a bike is better than in a car to get a good signal I'd have thought.
Last edited by: rtj70 on Tue 4 Jun 13 at 20:01
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